Question: Phospholamban is a protein leads to

That leads to sequestration of Ca2+ in endoplasmic reticulum Phospholamban is a protein contained within the sarcoplasmic reticulum that inhibits the activity of the sarcoplasmic calcium pump. Inactivation of the phospholamban results in an increase in calcium sequestration by the SR. In cardiac muscle, the rapid sequestration of Ca2+ shoens the duration of the contraction. In smooth muscle, sequestration causes the muscles to relax. Phospholamban has little effect on skeletal muscle contraction.

That increase interaction of calcium with myofilaments

That leads to sequestration of calcium in endoplasmic reticulum

That leads to sequestration of calcium by mitochondria


Question: DNA estimation can be done by


Question: Glycolysis occurs in

Ans. is 'a' i.e. Cytosol Reactions/PathwaysSiteGlycolysisCytosolKreb's cycleMitochondriaElectron transport chainMitochondriaHMP shuntCytosolFatty acid synthesisCytosolFatty acid oxidationMitochondriaOxidation of very long chain fatty acidsPeroxisomesGlycogenesisCytosolGlycogenolysisCytosolGluconeogenesisBoth cytosol & mitochondriaUrea cycleBoth cytosol & mitochondria


Question: Hexosaminidase A deficiency causes

Tay Sach&;s disease is a lipid storage disease. Due to deficiency of hexosaminidase A.GangliosideRef: DM Vasudevan, 7th edition, page no: 193


Question: Alkaptonuria an inherited metabolic disorder is due to the deficiency of


Question: Cellular bearings of hereditary diseases seen in

Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living things. All known cellular life and some viruses contain DNA. The main role of DNA in the cell is the long-term storage of information.


Question: Trapping parasites using NETs is assisted by

NEUTROPHILS AND EOSINOPHILS EMPLOY NETS TO ENTRAP PARASITESIn addition to ingesting small microorganisms such as bacteria by phagocytosis, neutrophils and eosinophils can assist in the elimination of larger invaders by trapping them within webs called neutrophil extracellular traps or NETsRef: Harper&;s Biochemistry; 30th edition; Chapter 54 White Blood Cells


Question: LCAT activates

Lipoproteins classes as per apoprotein contents Families: LP A Apolipoproteins: A-I and A-II Density class: HDL Mol. wt. range: 17000 to 28000 Function: LCAT activator, 'Scavenger'Ref: Textbook of Medical Biochemistry, Eighth Edition, Dr (Brig) MN Chatterjea, page no:445, Table 25.11


Question: Vitamin synthesised from amino acid is

Vitamin synthesized from amino acid niacin.Niacin, or nicotinic acid, is a substituted pyridine derivative. The biologically active coenzyme forms are nicotinamide adenine dinucleotide (NAD+) and its phosphorylated derivative, nicotinamide adenine dinucleotide phosphate.Reference: Lippincott Textbook of Biochemistry, fifth edition, pg no. 379


Question: Binding of proteins to DNA is regulated by


Question: Banding technique most commonly employed for cytogenetic analysis

G-banding (most common) R-banding Q-banding C-banding T-banding G stands for Giemsa R stands for "reverse" Q stands for Quinacrine Fluoroescent dye C stands for Constitutive heterochromatin or Centromere T stands for telomeres to produce a visible karyotype Dark regions are heterochromatin (AT) Light regions are Euchromatin (GC) Dark regions are euchromatin Bright regions are heterochromatin


Question: Glucose is linked to haemoglobin through

*When blood glucose enters the erythrocytes, it glycates the e-amino group of lysyl residues and the amino terminals of hemoglobin.*The fraction of hemoglobin glycated, normally about 5%, is propoionate to blood glucose concentration.*Since the half-life of an erythrocyte is typically 60 days, the level of glycated hemoglobin (HbA1c) reflects the mean blood glucose concentration over the preceding 6 to 8 weeks.*Measurement of HbA 1c therefore provides valuable information for management of diabetes mellitus.*Enzymatic addition of any sugar to a protein is called " glycosylation", while non-enzvmatic process is termed "glycation".*Interpretation of HbA1C valuesHbA1C valuesInterpretation <5.5 % Normal 5.5 - 7 % Adequate control 7 - 8 % Inadequate control 8 - 9 % Poor control Any values between 5.6 and 6 .4 are to be considered as impaired glucose tolerance. Value above 6 .5 % is considered as diabetic Harper's illustrated Biochemistry ,30th ed ,page 59


Question: Phosphofructokinase is the key enzyme of

Step 3 of Glycolysis -6-phosphate is fuher phosphorylated to fructose1,6-bisphosphate. The enzyme is phosphofructokinase. ii.PFK is an allosteric, inducible, regulatory enzyme. It is an impoant key enzyme of this pathway. This is again an activation process, the energy being derived by hydrolysis of yet another molecule of ATP. This irreversible step is the rate-limiting reaction in glycolysis. However, during gluconeogenesis, this step is circumvented by fructose-1,6-bisphosphatase.Ref: DM Vasudevan, 7th edition, page no: 109


Question: Main lipid component of LDL

LipoproteinSourceDiameter (nm)Density (g/ml)Main lipid ComponentApolipoproteinsLDLVLDL20-251.019-1.063CholesterolB-100Ref: Harper&;s biochemistry; 30th edition; Chapter 25; Lipid Transpo & Storage


Question: Fatty acids are the main source of energy for

Fed state Preferred fuel
Starvation preferred fuel

RBC

Glucose
Glucose

Heart

Fatty acids
Ketone bodies

Brain

Glucose
Ketone bodies

Liver

Glucose
Fatty acids / protein

Muscle

Glucose
Fatty acids

Adipose tissue

Glucose
Fatty acids.


Question: The mineral having action like vitamin E

Selenium is having action like VitE. Selenium acts as a nonspecific intracellular anti-oxidant. This action of Se is complementary to vitamin E. Availability of vitamin E reduces the selenium requirement. In Se deficiency, tissue vitamin E content is depleted. Reference: Vasudevan Textbook of Biochemistry pg no. 430


Question: The most predominantly occurring amino acid in collagen is

Tropocollagen, the repeating unit of a mature collagen fiber, consists of three collagen polypeptides, each containing about 1000 amino acids, bundled together in a unique conformation, the collagen triple helix. Every third amino acid residue in collagen is a glycine residue. Collagen is also rich in proline and hydroxyproline, yielding a repetitive Gly-X-Y pattern in which Y generally is proline or hydroxyproline.Reference: Explanation: Harper's Biochemistry; 30th edition; Chapter 5; proteins: higher Orders of Structure


Question: Urea is produced by the enzyme

UREA CYCLE: STEP 1 :One molecule of ammonia condenses with CO2 in presence of two molecules of ATP to form carbamoyl phosphate. STEP 2 :Formation of Citrulline: The carbamoyl group is transferred to the NH2 group of ornithine by ornithine transcarbamoylase. STEP 3:Formation of ARGININOSUCCINATE One molecule of aspaic acid adds to citrulline forming a carbon to nitrogen bond, which provides the 2nd nitrogen atom of urea.Argininosuccinate synthetase catalyzes the reaction. STEP 4 : Formation of Arginine Argininosuccinate is cleaved by argininosuccinate lyase to arginine and fumarate. STEP 5: Formation of Urea. The finsl reaction of the cycle is the hydrolysis of argine to urea and ornithine by arginase REF:DM VASUDEVAN TEXTBOOK :EIGHTH EDITION, Page no:258 & 259.


Question: Inhibitor of F0 F1 ATPase in electron transpo chain is

Inhibitors of electron transpo chainComplex I Complex II Complex III Complex IV AmobarbitalRotenonePericidin AGuanethidine Chlorpromazine Malonate Carboxin Antimycin A, BAL Naphthoquinone PhenforminCarbon monoxide CyanideHydrogen sulphide Azide Inhibitors of oxidative phosphorylationuBlocking reentry of protons through ATP synthase - Oligomycin , VenturicidinuInhibitors of ATP - ADP exchange - Atractyloside , BongregateuIonophores - Valinomycin , GramicidinUncouplers of oxidative phosphorylationuPhysiological uncouplers - Thermogenin, Thyroxine, Long chain fatty acids, Unconjugated bilirubinuSynthetic uncouplers - 2,4 Dinitrophenol, 2,4 Dinitrocresol, Calcium, Aspirin, DicoumarolHarper's illustrated Biochemistry , 30th ed , page 133


Question: Colloidal osmotic pressure of plasma is by


Question: Glutamate is not a precursor of

Glutamate is formed from histidine and not vice versa. Pg no.244.proline can be synthesized from glutamate with minor modification of catabolic pathway. Also glutamate is formed from proline. Pg no.201. Fig 15.7. ammonia pool is formed from glutamate also. Pg no.199.fig 15.3.Meister cycle. Glutamate is formed from glutathione and vice versa. It&;s a cycle.Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 243, fig; 18.13


Question: Polyol pathway is responsible for formation of

Polyol pathway is responsible for the formation of fructose from glucose Fig: The sorbitol (polyol) pathway


Question: Free SH group is present in

This is a tricky question. Option a, b and c have sulphur. But, only cysteine contains SH group. EXTRA EDGE:- Sulphur containing amino acids: Cysteine Methionine Homocysteine Taurine Sulfhydryl/thiol group-containing amino acids: Cysteine Homocysteine Sulfhydryl/thiol group-containing proteinogenic amino acids: Cysteine


Question: Thyroid peroxidase is not involved in

Inorganic iodine enters the body primarily as iodide, I-. After entering the thyroid follicle (or thyroid follicular cell) a Na+/I-sympoer (NIS) on the basolateral side, iodide is shuttled across the apical membrane into the colloid pendrin, after which thyroid peroxidase oxidizes iodide to atomic iodine (I) or iodinium (I+).The "organification of iodine," the incorporation of iodine into thyroglobulin for the production of thyroid hormone, is nonspecific; that is, there is no TPO-bound intermediate, but iodination occurs reactive iodine species released from TPO.The chemical reactions catalyzed by thyroid peroxidase occur on the outer apical membrane surface and are mediated by hydrogen peroxide.Ref: DM Vasudevan, 7th edition, page no: 673

Frequent epitope of autoantibodiesent epitope

Secretion of thyroglobulin into the colloid

Liberates iodine for addition on to thyrosine resideues on thyroglobulin


Question: Energy source used by brain in later days of Starvation is

B i.e. Ketone bodies REF: Lippincott book of biochemistry 6th ed.


Question: Flexibility of protein depends on

Glycine is one among the commonest amino acids found in protein structure. Being small and non-polar, glycine  is  mostly  present in  the interior structure of  protein.
Satyanarayana, Ed 3, Pg 302


Question: Hemoproteins are a) Cytochrome Cb) Cytochrome 450c) Myoglobind) Hemoglobine) Catalase

Hemoproteins (Proteins containing heme prosthetic group) are hemoglobin, myoglobin, cytochromes (cytochrome C, cytochrome p456), catalase, peroxidase, tryptophan pyrrolase and nitric oxide synthase.


Question: Hypolipidemic agents act on

HMG CoA reductase
Hypolipidemic drugs (statins) inhibit HMG-CoA reductase


Question: Major amino acid released from muscle during starvation

Glucose-Alanine cycle (Cahill cycle) is transpoed to liver, transaminated to pyruvate and conveed to glucose. This glucose may again enter the glycolytic pathway to form pyruvate, which in turn, can be transaminated to alanine. -alanine cycle is impoant in conditions of starvation (Fig. 9.30). Thus net transfer of amino acid (nitrogen) from muscle to liver and corresponding transfer of glucose (energy) from liver to muscle is affected. cycle is intimately related with Cori&;s cycleRef: DM Vasudevan, 7th edition, page no: 120


Question: Daily requirement of vitamin D in children is


Question: VLDL is formed in

Chylomicrons are found in "chyle" formed only by the Lymphatic system draining the intestine. However, it is now realised that a smaller and denser paicle similar to VLDL is now known to be synthesised in small quantity in intestinal cells also. Chylomicrons formation fluctuates with the load of TG absorbed, whereas VLDL formation is quantitatively less, but is more constant and occurs even in the fasting state. However, bulk of plasma VLDL is of hepatic origin, being the vehicle for transpo of TG from Liver to extrahepatic tissues (carrier of "endogenous" TG). There are many similarities in the mechanism of formation of chylomicrons by intestinal epithelial cells and VLDL by hepatic parenchymal cells. Salient Features * Chylomicrons and VLDL are synthesised in intestinal mucosal cells and Liver cells respectively. Polysomes on rough endoplasmic reticulum (ER) of these tissues synthesise apo-B48 and apo-B100 respectively. * TG is synthesised in smooth endoplasmic reticulum (ER) of both tissues. * Microsomal and cytoplasmic enzymes paicipate in cholesterol synthesis. * In the smooth endoplasmic reticulum (ER) of intestinal mucosal cells and Liver cells, the lipids are incorporated with apo-B48 and apo-B100 to form chylomicrons and VLDL respectively. * B-apoproteins are finally glycosylated in the Golgi- complex, which then packs the lipoproteins into secretory vesicles and budded off from Golgi cisternae. Release: Chylomicrons and VLDL are released from either the intestinal or hepatic cell by fusion of the "secretory vacuole" with the cell membrane, i.e. by reverse Pinocytosis. Chylomicrons pass into the spaces between the intestinal cells, eventually making their way into the Lymphatic system ("Lacteals") draining the intestine. VLDL are secreted by hepatic parenchymal cells into the "Space of Disse" and then into the hepatic sinusoids.Ref: Textbook of Medical Biochemistry, Eighth Edition, Dr (Brig) MN Chatterjea, page no: 446-447


Question: Example of postranslational modification is

Ans. is 'c' i.e.,Phosphorylation Impoant post-translational modifications are :TrimmingCovalent modification : Phosphorylation, glycosylation hydroxylation, y-Carboxylation of clotting factor by vitamin K.Protein folding and Protein degradation


Question: Most stable amino acid at the physiological pH is

As histidine titrates in the physiological pH range it remains stable.


Question: Okazaki fragments are formed during the synthesis of

Okazaki fragments are sho, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication. They are complementary to the lagging template strand, together forming sho double-stranded DNA sections. Okazaki fragments are between 1000 and 2000 nucleotides long in prokaryotes (e.g. Escherichia coli) and are roughly 100 to 200 nucleotides long in eukaryotes. They are separated by ~SS120-nucleotide RNA primers and are unligated until RNA primers are removed, followed by enzyme ligase connecting (ligating) an Okazaki fragment onto the (now continuous) newly synthesized complementary strand. On the leading strand DNA replication proceeds continuously along the DNA molecule as the parent double-stranded DNA is unwound, but on the lagging strand, the new DNA is made in installments, which are later joined together by a DNA ligase enzyme. This is because the enzymes that synthesise the new DNA can only work in one direction along the parent DNA molecule and the two strands are anti-parallel. On the leading strand this route is continuous, but on the lagging strand, it is discontinuous. DNA is synthesised from 5&; to 3&;, so when copying the 3&; to 5&; strand, replication is continuous.


Question: Number of double bonds in arachidonic acid is

Arachidonic acid (20C)D5,8,11,14-all Timnodonic acid


Question: Glucose transporters present in the Beta cells of the Islets of Langerhans is


Question: Carbohydrate of blood group substance is

L-fucose is the carbohydrate poion of Blood group substances


Question: Anticodon is present in

At the opposite side of the acceptor, arm is the anti armIt recognizes the triplet nucleotide codon present in mRNA The specificity of tRNA resides in the anticodon site, which has base sequence complementary to that of mRNA codonRef: DM Vasudevan, 7th edition, page no: 597


Question: Ubiquitin is the key protein involved in

Ans. b (Protein degradation) (Ref. Harper's biochemistry 27th ed., Chapter 45)# Ubiquitin targets many intracellular proteins for degradation.# It is estimated that a minimum of 4 ubiquitin molecules must be attached to commit a target molecule (e.g., a misfolded form of CFTR-protein involved in cystic fibrosis) to degradation in a proteasome.UBIQUITIN: A KEY MOLECULE IN PROTEIN DEGRADATION# Many proteins are degraded by the ubiquitin proteasome pathway, the discovery of which earned Aaron Ciechanover, Avram Hershko, and Irwin Roose a Nobel Prize.# There are 2 major pathways of protein degradation in eukaryotes:- One involves lysosomal proteases and does not require ATP.- The other pathway involves ubiquitin and is ATP-dependent.# Ubiquitin is small protein that plays key role in marking proteins for subsequent degradation in proteasomes.# Ubiquitin is known to be involved in:y- Degradation of proteins, and is particularly in disposal of misfolded proteins- Cell cycle regulation (degradation of cyclins),- DNA repair;- Activation of NFB,- Muscle wasting,- Viral infections, etc# Ubiquitin can be cleaved from a target protein by deubiquitinating enzymes and the liberated ubiquitin can be reused.MISFQLDED PROTEINS UNDERGO ENDOPLASMIC RETICULUM-ASSOCIATED DEGRADATION# Chaperones present in the lumen of the ER and in the cytosol target misfolded proteins to proteasomes. Prior to entering proteasomes, most proteins are ubiquitinated and escorted to proteasomes by polyubiquitin-binding proteins.- Diseases caused by lack of a particular functioning protein, due to its degradation as a consequence of misfolding, include:* Cystic fibrosis (misfolded CFTR protein),Q* Marfan syndrome (misfolded fibrillin),* Fabry disease (misfolded alpha galactosidase),* Gaucher's disease (misfolded beta glucocerebrosidase) and* Retinitis pigmentosa 3 (misfolded rhodopsin).* Some cancers may be associated with misfolding, and hence ineffective functioning, of tumour suppressor proteins such as von Hippel Lindau protein or p53.- Many protein misfolding diseases are characterised not by disappearance of a protein but by its deposition in insoluble aggregates within the cell. E.g.:* Alzheimer's disease (deposits of amyloid beta and tau),* Type II diabetes (depositis of amylin),* Parkinson's disease (deposits of alpha synuclein),* Spongiform encephalopathies such as Creutzfeldt-Jakob disease (deposits of prion protein).Educational Points:# The GOLGI APPARATUS Is Involved in Glycosylation & Sorting of Proteins.


Question: Glutamine synthetase is a

Ligases are enzymes that link two substrate together,usually with the simultaneous hydrolysis of ATP. Glutamine synthetase catalyses the amidation of glutamic acid to glutamine.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 49 and 224


Question: Enzyme activated by decrease in insulin glucagon ratio


Question: After overnight fasting, levels of glucose transpoers reduced in

GluT4 is the major glucose transpoer in skeletal muscle and adipose tissue.GluT4 is under the control of insulin.In Type 2 diabetes mellitus, membrane GluT4 is reduced, leading to insulin resistance in muscles and fat cells.Ref: DM Vasudevan, 7th edition, page no: 107


Question: Pyridoxal phosphate is required for

Glycogen phosphorylase removes glucose as glucose-1-phosphate from glycogen (phosphorolysis). It contains pyridoxal. Formation of branches in glycogen phosphate (PLP) as a prosthetic group. The alpha-1,4 linkages in the glycogen are cleaved. removes glucose units one at a time. Enzyme sequentially hydrolyses alpha-1,4 glycosidic linkages, till it reaches a glucose residue, 3-4 glucose units away from a branch point. It cannot attack the 1,6 linkage at branch point.Ref: DM Vasudevan, 7th edition, page no: 124


Question: Nobel prize in 2006 (recently) was given for the discovery of

If an investigator introduces into an organism a duplex RNA molecule corresponding in sequence to virtually any mRNA, Dicer nuclease cleaves the duplex into short segments, called small interfering RNAs (siRNAs). These short (21-25 nucleotide long) si RNAs usually form perfect RNA-RNA hybrid with their targets potentially anywhere within the length of mRNA where the complementary sequence exists. Formation of such RNA-RNA duplexes between si RNAs and mRNA results in reduced specific protein production because the si RNA - mRNA complexes are degraded, mostly in specific cytoplasmic organelles termed P-bodies. The process is known as RNA interference (RNAi) for which Nobel prize was given to Andrew Fire & Craig Mello in 2006.


Question: Excessive ultraviolet [uv) radiation is harmful to life'. The damage caused to the biological systems by ultraviolet radiation.

UV rays causes DNA damage by forming TT dimers (pyrimidine dimmers) which prevents replication


Question: Largest reserve of energy in body stored as

Fat (triglycerides) in the adipose tissues is the largest store of energy of the body.


Question: Benedict&;s test will be positive in the urine after administration of

Ascorbic acid is very common ingredient of many tonics.person taking such tonics will excrete ascorbic acid in urine. It is a powerful reducing agent. This may cause confusion, as Benedict&;s test is positive in such normal individuals.Ref: DM Vasudevan, 7th edition, page no: 318


Question: Number of optical isomers possible for Glucose is

Leber van Hoft rule for the number of stereoisomers is 2n where 'n' is the number of chiral centers. In open chain of glucose, there are 4 chiral centers. Hence it is 24 =16 isomers.Glucose, with four asymmetric carbon atoms, can form 16 isomers.Sugars have large numbers of stereoisomers because they contain several asymmetric carbon atoms.Ref: Harper&;s Biochemistry; 30th edition; Chapter 15; Carbohydrates of Physiological Significance


Question: Net ATP formed in glycolysis is

ATP Formation in the Glycolysis pathway Reaction Catalyzed by Method of ATP Formation ATP per mol of Glucose Glyceraldehyde-3-phosphate dehydrogenase Respiratory chain oxidation of 2 NADH 5* Phosphoglycerate kinase Substrate-level phosphorylation 2 Pyruvate kinase Substrate-level phosphorylation 2 Total 9 Consumption of ATP for reactions of hexokinase and phosphofructokinase 2 Net 7 *This assumes that NADH formed in glycolysis is transpoed into mitochondria by the malate shuttle. If the glycerophosphate shuttle is used, then only 1.5 ATP will be formed per mol of NADH. Reference: Harper; 30th edition; Page no: 169


Question: Rothera's test is for

Rothera's test is for Ketones in urine. Only acetone and acetoacetic acid can be detected using the Rotheras. Beta hydroxyl butyric acid is not detected. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 293


Question: Final product in anaerobic glycolysis

In glycolysis; During anaerobic (oxygen deficient) condition, when one molecule of glucose is conveed into 2 molecules of lactate, there is a net yield of 2 molecules of ATP. (refer,table:9.4)Ref: DM Vasudevan, 7th edition, page no: 112


Question: Active form of folic acid

Active form of Folic acid is Tetrahydrofolate. A. The folic acid is first reduced to 7,8-dihydrofolic acid and fuher reduced to 5,6,7,8-tetrahydrofolic acid (THFA) . Both reactions are catalyzed by NADPH dependent folate reductase. B. The THFA is the carrier of one-carbon groups. One carbon compound is an organic molecule that contains only a single carbon atom. The following groups are one carbon compounds: i.Formyl (-CHO) ii.Formimino (-CH=NH) iii.Methenyl (-CH=) iv.Methylene (-CH2-) v.Hydroxymethyl (-CH2OH) vi. Methyl (-CH3) C.These one carbon compounds are attached either to the 5th or to the 10th or to both 5 and 10 nitrogen atoms of THFA. The one-carbon metabolism and their interconversions D.Methyl group in N5-methyl THFA is used for synthesis of active methionine, which takes pa in transmethylation reactions. Such transmethylation reactions are required for synthesis of choline, epinephrine, creatine, etc. Reference: Vasudevan Textbook of Biochemistry pg no. 401


Question: Night blindness is due to


Question: Oncogenes can be best studied by

Transfection is the process of deliberately introducing naked or purified nucleic acidsinto eukaryotic cells. It may also refer to other methods and cell types, although other terms are often preferred: "transformation" is typically used to describe non-viral DNA transfer in bacteriaand non-animal eukaryotic cells, including plant cells. In animal cells, transfection is the preferred term as transformation is also used to refer to progression to a cancerous state (carcinogenesis) in these cells. Transduction is often used to describe virus-mediated gene transfer into eukaryotic cells. Ref satyanarayana 4e


Question: Gene transfer in bacterial system by

Transformation is one of three processes for horizontal gene transfer, in which exogenous genetic material passes from bacterium to another, the other two being conjugation (transfer of genetic material between two bacterial cells in direct contact)


Question: Karyotyping under light microscopy is done by

G-banding, G banding, or Giemsa banding is a technique used in cytogenetics to produce a visible karyotype by staining condensed chromosomes.It is useful for identifying genetic diseases through the photographic representation of the entire chromosome complement.


Question: Physiological uncoupler among the following is

Thermogenin (or the uncoupling protein) is a physiological uncoupler found in brown adipose tissue that functions to generate body heat, paicularly for the newborn and during hibernation in animals. Reference: Harper; 30th edition; Page no: 13


Question: Cytochrome C oxidase is inhibited by

Site-III (Complex IV) * Cyanide Inhibits terminal * H2S * Azide transfer of electrons to molecular O2 * Co (Carbon monoxide): Inhibits Cyt. oxidase by combining with O2 binding site. It can be reversed by illumination with light.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 143


Question: Cellular oxidation is inhibited by


Question: Cofactor of carbonic anhydrase is

The active site of most carbonic anhydrases contains a zinc ion; they are therefore classified as metalloenzymes. One of the functions of the enzyme in animals is to interconve carbon dioxide and bicarbonate to maintain acid-base balance in blood and other tissues and to help transpo carbon dioxide out of tissues.


Question: Amino acid used in the synthesis of purines

Purine contains glycine at 7th position and amino gp of aspaate at 1st position. No other amino acids present.Ref: Textbook of biochemistry for medical students, seventh edition, page no: 563, fig: 43.10


Question: Maximum source of linoleic acid is

Ans. is 'b' i.e. Sunflower oil Dietary sources of linoleic acidSafflower oil 73%Com oil 57%Sunflower oil 56%Soyabean oil 51%* Linoleic acid is an essential fatty acidEssential fatty acids are those that cannot be synthesized by human bodies. These are*Linoleic acidLinolenic acidArachidonic acidEicosapentaenoic acidOf these essential fatty acids the most important essential fatty acid is- linoleic acid* (because it serves as a basis for the production of other essential fatty acids).Dietary sources of other EFAArachidonic acid -Meat, eggs, milk*Linoleic acid -Soyabean oil*Eicosapentaenoic acid -Fish oil*Also Remember * Richest source of vit A -Fish liver oil** Richest source of vit D -Cod liver oil** Richest source of vit K -Cow's milk** Richest source of vit B12 -liver** Richest source of folic acid -green leafy vegetables** Richest source of iron is -Jaggery** Richest source of iodine is -seafood's and cod liver oil*

Biosynthesis of Fatty Acids and Eicosanoids


Question: Cystine is formed by

The difference in structure of cysteine and cystine. Two molecules of cysteine are joined together by S--S bond to form one molecule of cystine. Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 504

Peptide bond between two cysteine molecule

Disulfide bond between cysteine molecule


Question: Sphingomyelinase deficiency is seen in

DiseaseEnzyme DeficiencyClinical SymptomsNiemann-PickdiseaseSphingomyelinaseEnlarged liver and spleen, mental retardation;fatal in early lifeRef: Harper&;s Biochemistry; 30th edition; Chapter 24; 24 Metabolism of Acylglycerols & Sphingolipids


Question: Zellweger syndrome is due to

Zellweger syndrome is due to absence of peroxisomes in all most all tissues, as a result of which long chain fatty acids are not oxidized and accumulated in live and brain. So this syndrome is also called as cerebrohepatorenal syndrome.


Question: Sweaty feet odor in body fluids occur d/t deficiency of

Sweaty feet odor in body fluids a/ w neurological problems occur in deficiency of FAD linked dehydrogenase specific for isovaleryl COA.


Question: Histidine decarboxylase is present in

Histamine is formed from histidine by decarboxylation, catalyzed by histidine decarboxylase. The effects of histamine are summarised in Table 16.3. Smooth muscle contraction, enhanced vascular permeability, increased acid secretion are the impoant actions. So histamine causes fall in blood pressure. The major cells producing histamine are platelets, mast cells, and basophils. Ceain antigens such as penicillin will elicit IgE antibodies that are fixed on the mast cells. When the next dose of penicillin is injected, it reacts with the antibodies; and degranulation of mast cells takes place. Histamine and slow reacting substance (SRS) are released. This leads to peripheral vasodilatation, fall in blood pressure and anaphylaxis.


Question: Marble bone disease, characterized by increased bone density is due to mutation in the gene encoding

Osteopetrosis  (marble  bone  disease),  characterized  by increased bone density, is a rare condition characterized by  inability  to  resorb  bone.  One  form  occurs  along  with  renal tubular acidosis and cerebral calcification. It is due to mutations  in  the  gene  (located  on  chromosome  8q22) encoding carbonic anhydrase II (CA II), one of four isozymes of carbonic anhydrase present in human tissues. In osteoclasts involved in bone resorption, CA II apparently provides protons to neutralize the OH−  ions left inside the cell when H+  ions are pumped across their ruffled borders.
Thus, if CA II is deficient in activity in osteoclasts, normal bone resorption does not occur, and osteopetrosis results. The mechanism of the cerebral calcification is not clear, whereas the renal tubular acidosis reflects deficient activity of CA II in the renal tubules.
Harper, Ed 30, Pg No 642, 643


Question: Iron is stored in human body in combination with


Question: Type of collagen found in basement membrane is

Type I is the most abundant form,seen in connective tissues in almost all regions of the body. Type II is mainly seen in cailage and vitreous humor. Type III is seen in skin, lung and vascular tissues and Type IV is seen in basement membranes.others are seen in minor quantities. About 30 genes are resposible for collagen synthesis ,and the enzymes necessary for collagen synthesis. REFERENCE : DM VASUDEVAN TEXTBOOK SEVENTH EDITION ; PAGE NO ;720


Question: Aniacinosis results in


Question: Beta alanine is formed by

Reference: Harpers illustrated biochemistry 30th edition


Question: In G6PD deficiency patient, hemolysis is due to decrease in

G6PD deficiency is an inherited sex-linked trait. Although the deficiency occurs in all the cells of the affected individuals, it is more severe in RBC. HMP shunt is the only means of providing NADPH in the erythrocytes. Decreased activity of G6PD impairs the synthesis of NADPH in RBC. This results in the accumulation of methemoglobin and peroxides in erythrocytes leading to hemolysis.
Glucose-6-phosphate dehydrogenase deficiency is most common and pyruvate kinase deficiency is 2nd most common enzyme deficiency related hemolytic anemia.


Question: Ligand for LDL

LOW-DENSITY LIPOPROTEINS (LDL) LDL transpos cholesterol from liver to peripheral tissues. The only apoprotein present in LDL is apo B100. Most of the LDL paicles are derived from VLDL, but a small pa is directly released from liver. The half-life of LDL in blood is about 2 days.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 153


Question: Increased levels of alanine in serum after fasting suggest

During starvation, muscle proteins are degraded to serve amino acids (especially alanine) as substrates for gluconeogenesis.
Alanine also arises from transamination of pyruvate in the muscles.
Alanine is transported to liver for gluconeogenesis.

Increased release of alanine from muscle

Reduced amino acid utilisation for gluconeogenesis

Break in continuity of plasma membrane resulting in leakage of amino acids


Question: Leucine is a aminoacid with a

Leucine is non-polar amino acid, i.e. its side chain (R) is nonpolar.


Question: Enzyme deficients in von gierke&;s disease


Question: Restriction enzymes have been found in

A restriction enzyme or restriction endonuclease cleaves DNA into fragments at or near specific recognition sites within the molecule known as restriction sites. These enzymes are found in bacteria and provide a defence mechanism against invading viruses. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 579


Question: Gamma amino butyrate is synthesized from

Gamma-aminobutyric acid or GABA is formed by decarboxylation of glutamate in presence of enzyme glutamate decarboxylase.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 224, Fig 17.2


Question: Marker of peroxisomes is

Marker enzymesPeroxisomes-Uric acid oxidaseMitochondria-ATP synthaseLysosome-cathepsinGolgi complex-galactosyl transferaseMicrosome-glucose 6 phosphatasesCytoplasm-lactate dehydrogenases


Question: Non polar lipid act as


Question: The best technique useful for initial viral load estimation is


Question: Galactosemia is due to deficiency of the following enzymes

(A) Galactose-1-phosphate uridyl transferase[?]GALACTOSAEMIA is a rare genetic metabolic disorder that affects an individual's ability to metabolize the sugar galactose properly.oGalactosemia follows an autosomal recessive mode of inheritance that confers a deficiency in an enzyme responsible for adequate galactose degradation.TypeEnzyme deficiencyAccumulating metabolitesIGalactose 1-phosphate uridyltransferaseGalactose, galactose-1 phosphate, galactitol, galactonateIIGalactokinaseGalactose, galactitolIIIUDP-galactose epimeraseGalactose-1 phosphate, UDP galactose


Question: To synthesize insulin on a large scale basis, the most suitable staing material obtained from the beta cells of the pancreas is

the mRNA act as messenger transpoing the information in the gene in DNA to the protein synthesizing machinery in the cytoplasmRef: DM VASUDEVAN, 7th edition, page no: 558


Question: Part of eukaryotic DNA contributing to polypetide synthesisa) Exonb) Enhancerc) Leader sequenced) tRNAe) ncRNA

Exon (coding protein) : Sequence of a gene that is represented as m-RNA.
Enhancer: Are special cis-acting DNA sequences that increase the rate of initiation of transcription of eukaryotic genes by RNA polymerase II.
Leader sequence: Sequence at the 5' end of a mRNA that is not translated into protein.
Non-coding RNA (nc RNA): Functional RNA that is not translated into a protein. Non-coding RNAs include tRNA, rRNA, Sno RNA, mi-RNA, si-RNA, pi-RNA and long nc RNA like Xist & HOT AIR.


Question: Not glucogenic is

CLASSIFICATION OF AMINO ACIDS BASED ON METABOLISM - A. Purely Ketogenic - Leucine is purely ketogenic because it is conveed to ketone bodies. B. Ketogenic and Glucogenic - Lysine, Isoleucine, Phenylalanine, Tyrosine and Tryptophan are paially ketogenic and paially glucogenic. How ever in humans lysine is predominantly ketogenic. During metabolism, pa of the carbon skeleton of these amino acids will enter the ketogenic pathway and the other pa to glucogenic pathway. C. Purely Glucogenic - All the remaining 14 amino acids are purely glucogenic as they enter only into the glucogenic pathway. the glucogenic amino acids are: Alanine Arginine Asparagine Aspaic acid Cysteine Glutamic acid Glutamine Glycine Histidine Methionine Proline Serine Valine. PNEMONIC TO REMEMBER ESSENTIAL AMINO ACIDS -"Any Help In Learning These Little Molecules Proves Truely Valuable" This stands for Arginine, Histidine, Isoleucine, Leucine, Threonine, Lysine, Methionine, Phenylalanine, Tryptophan and Valine in that order. Arginine and Histidine are semi-essential amino acids; while others are essential. REF:DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY,EIGHTH EDITION,PG.NO.,26,27.


Question: Source of ribose is

By-products of HMP Shunt pathway are NADPH and riboseRef: DM Vasudevan; 7th edition; Page no: 130


Question: Gene is

A cistron is a gene. The term cistron is used to emphasize that genes exhibit a specific behavior in a cis-trans test; distinct positions (or loci) within a genome are cistronics The words cistron and gene were coined before the advancing state of biology made it clear that the concepts they refer to are practically equivalent. Ref satyanarayana 4e


Question: Transpo of glucose from the lumen to the mucosal cell is dependent on the diffusion of

Glucose and galactose are absorbed by a sodium-dependent process. They are carried by the same transpo protein (SGLT 1)The SGLT 1 transpoer is coupled to the Na+-K+ pump, allowing glucose and galactose to be transpoed against their concentration gradients.Harper 30th edition Pg:538


Question: Enzymes act by reducing the

"All enzymes accelerate reaction rates by lowering activation energy for the formation of transition states."Activation energy is the minimum energy required to sta a chemical reaction.Harper 30th edition pg: 77


Question: Vitamin B12 deficiency has A/E


Question: Substrate level phosphorylation is by

substrate level phosphorylation-- Enzyme phosphoglycerate kinase- Enzyme pyruvate kinase.


Question: The amino acid that lacks chirality

Ans. is 'd' i.e. Glycine "The Alpha carbon of each amino acid is attached to four different chemical groups and is therefore a chiral or optically active carbon atom. Glycine is the exception because its alpha carbon has two hydrogens substituents (2 H atoms attached to alpha carbon) and is therefore optically inactive (lacks chirality). "All amino acids except glycine exists as two stereoisomers (or optical isomers or enantiomers), designated asD (dextro) &L (levo) forms.All the amino acids found in proteins are of the L-configuration*Also rememberSmallest and simplest amino acid - Glycine*Amino acid responsible for flexibility of proteins is - Glycine*


Question: In hemoglobin the innate affinity of heme for carbon monoxide is diminished by the presence of

Ans. is 'b' i.e., His E-7 The heme has high affinity for carbon monoxide (about 25000 more than for oxygen)But when heme molecule is associated with Histidine E7 [( as occurs in myoglobin), its affinity for CO is drastically reduced, because the presence of His E7 creates a hindered environment for CO by disturbing the orientation of atoms in the heme moleculeSee what Harper writes- "Carbon monoxide (CO) binds to isolated heme about 25000times more strongly than does oxygen. The atmosphere contains traces of CO, and normal catabolism of heme itself forms small quantities of CO. Why then does not CO (rather than 02) occupy the sixth coordination position of the heme iron of myoglobin? The answer lies in the hindered environment of heme in myoglobin. The preferred orientation for CO to heme iron is with all three atoms (Fe, C, and O) perpendicular to heme ring.* While this orientation is possible for isolated heme, in myoglobin the distal histidine (His-E7) sterically hinders binding of CO at this angle. *Angles for bonding of oxygen and carbon monoxide to the heme iron of myoglobin. The distal E7 histidine hinders bonding of CO at the preferred (180-degree) angle to the plane of the heme ring. This forces CO to bind in a less favoured configuration and reduces the strength of the heme - CO bond over two orders of magnitude"


Question: The relationship between sulphonamide and PABA is

Sulfonamides have structural similarity with PABA .therefore, they competitively inhibit the enzyme responsible for the incorporation of PABA into dihydropteroic acid, the immediate precursor of folic acidRef: DM Vasudevan, 7th edition, page no: 491, 61


Question: Inhibition of glycolysis is increased supply of O2 is

Pasteur Effect - Under aerobic conditions, glycolysis is inhibited. This inhibitory effect of oxygen on glycolysis is known as Pasteur effect. REF:DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, EIGHTH EDITION,PG.NO.,134.


Question: Pyrimidine dimers are formed due to

Pyrimidine dimers are molecular lesions formed from thymine or cytosine bases in DNA photochemical reactions. Ultraviolet light induces the formation of covalent linkages by reactions localized on the C=C double bonds. In dsRNA (double-stranded RNA), uracil dimers may also accumulate as a result of UV radiation. Two common UV products are cyclobutane pyrimidine dimers (CPDs, including thymine dimers) and 6,4 photoproducts. These premutagenic lesions alter the structure of DNA and consequently inhibit polymerases and arrest replication. Dimers may be repaired by photoreactivation or nucleotide excision repair, but unrepaired dimers are mutagenic. Pyrimidine dimers are the primary cause of melanomas in humans Ref-Harpers illustrated biochemistry 30/e p279


Question: Carnitine helps in

Fatty acids are activated in the cytoplasm, but the beta-oxidation is in mitochondria. So transpo of fatty acids through the mitochondrial membrane is essential. The long chain fatty acyl CoA cannot pass through the inner mitochondrial membrane. Therefore a transpoer, carnitine is involved in transfer of fatty acids. Carnitine is beta-hydroxygamma- trimethyl ammonium butyrate,Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 131

Transpo of fatty acids from mitochandria to cytosol

Transpo of fatty acids from cytosol to mitochandria


Question: Number of ATP molecules and NADPH formed in each cycle of glycolysis In aerobic condition,

when oxygen is in plenty, the two NADH molecules, generated in the glyceraldehyde3-phosphate dehydrogenase reaction (step 5), can enter the mitochondrial electron transpo chain for complete oxidation. As each NADH provides 2.5 ATPs, this reaction generates 2.5 x 2 = 5 ATPs. Thus when oxygen is available, the net gain of energy from the glycolysis pathway is 7 ATPs. In aerobic conditions, Pyruvate is later oxidatively decarboxylated to acetyl CoA which enters the citric acid cycle for complete oxidation. Complete oxidation of glucose through glycolysis plus citric acid cycle will yield a net 32 ATPs. Ref: DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY,EIGHTH EDITION,PG.NO.,132.


Question: Immunoglobulin that crosses to the fetus from mother

IgG can cross placental barrier, and protects the newborn child from infections. These maternal antibodies are seen in neonatal circulation upto 2-4 months. Placental crossing of IgG explains the Rh isoimmunization. This occurs when mother is Rh negative, and fetus is Rh positive, and when ABO system antigens are similar to both mother and fetus. Ref: D M Vasudevan 7th edition Page no: 688, 689


Question: Urea cycle occurs in

Inside the cells of almost all tissues,transamination of amino acids produce glutamic acid. How ever , Glutamate dehydrogenase is available only in liver. Therefore ,the final deamination and production of ammonia is taking place in Liver.Which fuher enters Urea cycle.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 203


Question: The following metabolite is a derivative of tryptophan

Tryptophan is conveed to Seratonin, which is then acetylated and fuher methylated to form Metatonin.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 240, Fig no 18.10.


Question: Vitamin K is required for

Carboxylation The only known biological role of vitamin K is as a cofactor for an enzyme carboxylase that catalyzes carboxylation of glutamic acid residues on vitamin K-dependent proteins. The key vitamin K-dependent proteins include: Coagulation proteins: factors II (prothrombin), VII, IX and X Anticoagulation proteins: proteins C, S and Z Bone proteins: osteocalcin and matrix-Gla protein Gas6 is a vitamin K-dependent protein that is found throughout the nervous system, as well in the hea, lungs, stomach, kidneys, and cailage. These proteins have in common the requirement to be post-translationally modified by carboxylation of glutamic acid residues (forming gamma-carboxyglutamic acid) in order to become biologically active. Prothrombin, for example, has 10 glutamic acids in the amino-terminal region of the protein which are carboxylated. Without vitamin K. the carboxylation does not occur and the proteins that are synthesized are biologically inactive. Carboxylation of glutamic acid residues is critical for the calcium-binding function of those proteins. Also Know There are two naturally occurring forms of vitamin K: - phylloquinone synthesized by plants - menaquinones synthesized by intestinal bacteria Synthetic forms of vitamin K are: - menadiotze - menadiol - menadiol acetate


Question: Oxidative decarboxylation of pyruvate requires

Inside the mitochondria, pyruvate is oxidatively decarboxylated to acetyl CoA by pyruvate dehydrogenase (PDH). It is a multi-enzyme complex with 5 co-enzymes and 3 apo-enzymes.
The co-enzymes needed are:

Thiamine pyrophosphate (TPP)
Co-enzyme A (CoA)
FAD
NAD+
Lipoamide.
The enzyme part of the PDH complex is made up of three component enzymes.

Reference: Vasudevan 7th  ed, pg 116


Question: The apoprotein in HDL is mainly

Most important apoprotein in HDL → apo A-1
Most important apoprotein in chylomicrons → apo B-48
Most important apoprotein in LDL, IDL, VLDL → apo B-100


Question: Acrodermatitis enteropathica is a classical presentation due to deficiency of


Question: Initial amino acid in prokaryotic protein synthesis

Activation of amino acid is the first phase of translation, among which initiation of protein synthesis is the first step. It is divided into 4steps .1st one is recognition steps. In eukaryotes, the first amino acid incorporated is methionine(AUG codon). But in prokaryotes, the same codon stands for N-formyl methionine, which is the first amino acid.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 600


Question: Sweaty feet odour in body fluids occur due to deficiency of

The impaired enzyme in isovaleric acidemia is isovaleryl-CoA dehydrogenase. Vomiting, acidosis and coma follow ingestion of excess protein. Accumulated isovaleryl-CoA is hydrolyzed to isovalerate and excreted. Characteristic odor of sweaty feet is present.
Harper's Illustrated Biochemistry 30 th edition page no 309


Question: Enzyme responsible for the complete oxidation of glucose to CO2 to water is present in

CITRIC ACID CYCLE Synonyms: TCA cycle (tricarboxylic acid cycle), Krebs' cycle, Krebs' citric acid cycle. Points to Remember * It is a cyclic process. * The cycle involves a sequence of compounds interrelated by oxidation-reduction and other reactions which finally produces CO2 and H2O. * It is the final common pathway of break down/catabolism of carbohydrates, fats, and proteins. (Phase III of metabolism). * Acetyl-CoA derived mainly from the oxidation of either glucose or b-oxidation of FA and paly from ceain amino acids combines with oxaloacetic acid (OAA) to form citrate the first reaction of citric acid cycle. In this reaction acetyl-CoA transfers its 'acetyl-group' (2-C) to OAA. * By stepwise dehydrogenations and loss of two molecules of CO2, accompanied by internal re-arrangements, the citric acid is reconveed to OAA, which again stas the cycle by taking up another acetyl group from acetyl-CoA. * A very small catalytic amount of OAA can bring about the complete oxidation of active-acetate. * Enzymes are located in the mitochondrial matrix, either free or attached to the inner surface of the inner mitochondrial membrane, which facilitates the transfer of reducing equivalents to the adjacent enzymes of the respiratory chain. * The whole process is aerobic, requiring O2 as the final oxidant of the reducing equivalents. Absence of O2 (anoxia) or paial deficiency of O2 (hypoxia) causes total or paial inhibition of the cycle. * The H atoms removed in the successive dehydrogenations are accepted by corresponding coenzymes. Reduced coenzymes transfer the reducing equivalents to the electron-transpo system, where oxidative phosphorylation produces ATP moleculesRef: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 336


Question: Homocysteine is

Homocysteine is a non-proteinogenic alpha- amino acid Homologous to cysteine, differing by an additional methylene bridge (-CH2-) Synthesized from methionine.


Question: Mitochondrial membrane protein contain transporter of

The carrier proteins in inner mitochondrial membrane (IMM) are highly specific in their action. They permit movement of several molecules that are important for cellular function, such as ATP, H+, malate, pyruvate, citrate, glutamate, aspartate, a-ketoglutarate and phosphate.
It should be remembered that though shuttle systems move NADH produced in the cytosol into the mitochondria, there is no direct transporter for NADH. First reducing equivalent of NADH is transferred to malate which then is transported into the mitochondria and returns the reducing equivalent to mitochondrial NAD+ to form NADH. So, NADH is not transported but for one NADH produced in the cytosol one NADH is produced inside the mitochondria after transport of reducing equivalent by shuttle system.


Question: Beta oxidation of very long chain fatty acids occurs


Question: Dietary fibre is rich in


Question: Earliest symptom of Tay sach disease

Ans. is 'a' i.e., Exaggerated stale response Tay-Sach diseaseClinical symptoms are usually evident in the first year of lifeInitial signs are not dramatic and present as enfeeblement, spasticity and slow development.An exaggerated stale response to sound may be the most significant early sign of which a parent is aware.Other features are mental retardation, deterioration of vision and early death.


Question: Gluconeogenesis takes place in

Only liver can replenish blood glucose through gluconeogenesis because glucose-6phosphatase is present mainly in liver. So liver plays the major role in maintaining the blood glucose level.Ref: DM Vasudevan, 7th edition, page no: 118


Question: Reverse transcription involves

Generally, the genes are made up of DNA . Usually , DNA dependent RNA polymerase transfers the information of DNA to mRNA . But Retrovirus group , RNA acts as a template Based on this RNA , the enzyme , RNA dependent DNA polymerase or reverse transcriptase will make a new DNA strand. Reference : DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION ; PAGE NO : 593.


Question: Degeneracy of codons means

More than one codon for a single amino acid


Question: The ratio of carbon dioxide produced to oxygen consumed is known as

Respiratoryquotient (RQ) is the ratio of carbon dioxide produced/oxygen consumed RQ Glucose 1.00 Protein 0.81 Fat 0.71 Alcohol 0.66 Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 503


Question: Fluoride, used in the collection of blood samples for glucose estimation, inhibits the enzyme

Enolase requires Mg+ +, and by removing magnesium ions, fluoride will irreversibly inhibit this enzyme. Thus, fluoride will stop the whole glycolysis. So when blood collecting for sugar estimation, fluoride is added to the blood. If not, glucose is metabolized by the blood cells, so that lower blood sugar values are obtained.Ref: DM Vasudevan, 7th edition, page no: 111


Question: The biosynthesis of Epinephrine from Norepinephrine requires

S-adenosyl methionine (SAM) is the methyl donor for the conversion of Norepinephrine to Epinephrine.

Classification and metabolism of amino acids


Question: Cystine is formed from

The difference in structure of cysteine and cystine. Two molecules of cysteine are joined together by S--S bond to form one molecule of cystine.Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 504


Question: Transketolase requires

Vitamin B complexCo-enzyme formReactions used by the enzymeActivity assessmentThiamine Thiamine pyrophosphate Oxidative decarboxylation | RBC transketolase activity Riboflavin Flavin adenine dinucleotide Oxido reduction , Deamination | RBC glutathione reductase activity Niacin Nicotinamide adenine dinucleotideOxido reduction , Deamination Koenig reaction , Xanthurenic index Pantothenic acid Co enzyme A , ACP Co A derivatives , Acyl carrier proteins Pyridoxine Pyridoxal phosphate Transamination , Decarboxylation Tryptophan loading test,Xanthurenic indexBiotin Biotin Carboxylation MethylcobalamineHomocysteine methyl transferaseMethyl malonylaciduria index Folic acidFIGLU test Harper's illustrated Biochemistry ,30th ed ,page 190


Question: In muscle, phosphorylase b is kept in inactivated state by


Question: Primary Hyperoxaluria occurs in defect in metabolism of

Primary Hyperoxaluria : increased excretion of oxalates is observed upto 600 mg/day ,compred to a normal of 50 mg /day .The oxaluria is due to increased production of oxaltes. It is an autosomal recessive trait. The disease is due to a protein targetting defect.Normally , the enzyme alanine glyoxalate amino transferase is located in hepatic peroxiomes :but in these patients the enzyme is present in mitochondria. This leads to increased pool size of glyoxalate ,and excess production of oxalate.Rnal depositionof oxalateswould cause nephrolithiasis,renal colic and hematuria.Extrarenal oxalosis may be seen in hea, blood vessels ,bone etc TYPE 2 primary hyperoxaluria is a milder condtion causing only urolithiasis and results from deficient activity of cytoplasmic glyoxalte oxidase. The pricipl of management is to increase oxalate excretion by increased water intake.Also try to minimize dietery intake of oxalates by restricting the intake of leafy vegetables,sesame seeds, tea ,cocoa,beetroot,spinach etc. in normal persons , oxalate can arise from Glyoxalate metabolism. from ingestion of leafy vegetables. from ascorbic acid degradation.The third source is minimal in human beings. REF : DM VASUDEVAN TEXTBOOK ,7TH EDITION ; Pageno :213


Question: Amber codon refers to

Stop codons UAA - ochre; UAG - amber; UGA - opal.


Question: Acridine orange is a fluorescent dye used to bind

DNA and RNA Acridine orange is a nucleic acid selective metachromatic stain useful for cell cycle determination Acridine orange interacts with DNA and RNA by intercalation or electrostatic attraction respectively - DNA intercalated Acridine orange fluoresces green - RNA electrostatically bound acridine orange fluoresces red It may distinguish between quiescent and activated proliferating cells and may also allow differential detection of )multiple GI compaments. - Acridine orange is also a useful method for measuring apoptosis and for detecting intracellular pH gradients and the measurement of proton pump activity. Uses of Acridine orange Demonstration of mucin Staining of DNA and RNA As a stain for electron microscopy study of mitochondria) osteoclasts Distinguish proliferating and resting cells Genetic determination of plasmodium falciparum and H. Pylori Also know D.N.A. can be best demonstrated by --> Feulgen Other methods of demonstrate D.N.A --> Methyl green pyronin, Gallocyanin chrome alum method Method of choice for demonstrating R.N.A --> Methyl green pyronin Other methods to demonstrate R.N.A. - Gallocyanin chroms alum, Acridine orange


Question: Last electron acceptor in electron transpo chain is

Complex IV: Cyt-c Oxidase The system functions: * As proton pump * Catalyses transfer of electrons to molecular O2 to form H2O. This is the terminal component of ETC. It catalyzes the transfer of electrons from Cyt-c to molecular O2 Cyt-a, Cu++ ions and Cyt-a3.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 142


Question: Fireflies produce light due to

Light production in fireflies is due to a type of chemical reaction called bioluminescence. This process occurs in specialized light-emitting organs, usually on a firefly&;s lower abdomen. The enzyme luciferase acts on the luciferin, in the presence of magnesium ions, ATP, and oxygen to produce light. Gene coding for these substances has been inseed into many different organisms (see Luciferase - Applications). Firefly luciferase is used in forensics, and the enzyme has medical uses -- in paicular, for detecting the presence of ATP or magnesium. All fireflies glow as larvae. Bioluminescence serves a different function in lampyrid larvae from the function served in adults. It appears to be a warning signal to predators since many firefly larvae contain chemicals that are distasteful or toxic.


Question: Principal serum enzyme used in clinical diagnosis of Wilson disease

Serum enzymeDiseaseAspaate aminotransferase(AST, or SGOT)Myocardial infarctionAlanine aminotransferase(ALT, or SGPT)Viral hepatitisAmylaseAcute pancreatitisCeruloplasminHepatolenticular degeneration(Wilson disease)Creatine kinaseMuscle disorders and myocardialinfarctiong-Glutamyl transferaseVarious liver diseasesLactate dehydrogenaseisozyme 5Liver diseasesLipaseAcute pancreatitisb-GlucoscerebrosidaseGaucher diseasePhosphatase, alkaline(isozymes)Various bone disorders,obstructive liver diseasesRef: Harper&;s Biochemistry; 30th edition; Chapter 7 Enzymes: Mechanism of Action


Question: Cardiac enzymes are

These tests can measure blood levels of the enzyme creatine phosphokinase (CPK), also called creatine kinase (CK), and a more specific form of this enzyme called CK-MB. Additionally, cardiac enzyme tests can be used to check the blood levels of the proteins myoglobin and troponin.


Question: Niemann Pick disease is due to deficiency of

(C) Sphinomyelinase EXAMPLES OF SPHINGOLIPIDOSESDiseaseEnzymeDeficiencyLipid AccumulatingClinical SymptomsTay-Sachs diseaseHexosaminidase ACer--Glc--Gal(NeuAc) / GalNAcMental retardation, blindness, muscular weakness. GM2 Ganglioside Fabry's diseasea-GalactosidaseCer--Glc--GalGalSkin rash, kidney failure (full symptoms only in Globotriaosylceramidemales; X-linked recessive).MetachromaticleukodystrophyArylsulfatase ACer--Gal/OSO3Mental retardation and psychologic disturbances in adults; demyelination. 3-SulfogalactosylceramideKrabbe's diseaseb-GalactosidaseCer/ GalMental retardation; myelin almost absent. Galactosylceramide Gaucher's diseaseb-GlucosidaseCer/ GlcEnlarged liver and spleen, erosion of long bones, Glucosylceramidemental retardation in infants.Niemann-Pick diseaseSphingomyelinaseCer/ P--cholineSphingomyelinEnlarged liver and spleen, mental retardation; fatal in early life.Farber's diseaseCeramidaseAcyl/SphingosineHoarseness, dermatitis, skeletal deformation, mental retardation; fatal in early life.


Question: Sickle cell anemia is the clinical manifestation of homozygous genes for an abnormal haemoglobin molecule. The event responsible for the mutation in the Beta chain is

Point mutation is a random SNP (single-nucleotide polymorphism) mutation in the deoxyribonucleic acid (DNA) that occurs at one point. Point mutations usually take place during DNA replication. DNA replication occurs when one double-stranded DNA molecule creates two single strands of DNA, each of which is a template for the creation of the complementary strand. A single point mutation can change the whole DNA sequence. Changing one purine or pyrimidine may change the amino acid that the nucleotides code for.Point mutation is a random SNP (single-nucleotide polymorphism) mutation in the deoxyribonucleic acid (DNA) that occurs at one point. Point mutations usually take place during DNA replication. DNA replication occurs when one double-stranded DNA molecule creates two single strands of DNA, each of which is a template for the creation of the complementary strand. A single point mutation can change the whole DNA sequence. Changing one purine or pyrimidine may change the amino acid that the nucleotides code for.Ref: DM Vasudevan, 7th edition, page no: 612


Question: The brush border bound hydrolase linked with sucrase is

Hydrolysis of sucrose (optical rotation +66.5deg) will produce one molecule of glucose (+52.5deg) and one molecule of fructose (-92deg). Therefore the products will change the dextrorotation to levorotation, or the plane of rotation is inveed. Equimolecular mixture of glucose and fructose thus formed is called inve sugar. The enzyme producing hydrolysis of sucrose is called sucrase or invease. Honey contains inve sugar. Inve sugar is sweeter than sucrose.Ref: DM Vasudevan, page no: 68


Question: In cytochrome P450, P stands for

Molecular oxygen is incorporated into a variety of substrates by enzymes designated as oxygenases; many drugs, pollutants, and chemical carcinogens (xenobiotics) are metabolized by enzymes of this class, known as the cytochrome P450 systemCytochromes P450 Are Monooxygenases Impoant in Steroid Metabolism & for the Detoxification of Many DrugsReaction and also works together with cytochromes P450 in drug detoxificationRef: Harper&;s biochemistry text, 30th edition, biological oxidation


Question: Essential fatty acid

Linoleic and a-linolenic acids are the only fatty acids known to be essential for the complete nutrition of many species of animals, including humans, and are termedthe nutritionally essential fatty acids. In most mammals, arachidonic acid can be formed from linoleic acid.Ref: Harper 9e pg: 238


Question: Under metabolic conditions associated with a high rate of fatty acid oxidation, liver produces


Question: Components of chromosome area) DNAb) t RNAc) m RNAd) r RNAe) Histone

Nucleosomes are further arranged into increasingly more complex structures that organize into chromosomes.
Chromosomes are made up of DNA, histones, and non-histone protein.


Question: Cytochromes are

Cytochromes These are very impoant enzymes which contain haem and are involved in cellular oxidation. ( Fe-porphyrin protein) The oxidized form of cytochrome possesses a single Fe+3 ion and is called ferricytochrome. It is reduced to ferrocytochrome having a Fe+2 ion on accepting an electron. * Cytochromes are identified by their characteristic absorption spectra. Ferricytochrome shows diffuse and non-characteristic absorption band invisible spectrum. Ferrocytochrome exhibit characteristic absorption bands called a aa, b bb, and ggg-soret bands. * Cytochromes are categorized into different groups according to the light wavelength at which the a-band shows its peak (a absorption maxima). They also differ with respect to haem prosthetic group, the apoprotein, and binding between the haem and apoprotein.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 137


Question: In leucine zipper model, Leucine residue is seen after every

*An a helix in which there is a periodic repeat of leucine residues at every seventh position. *This occurs for eight helical turns and four leucine repeats. * Similar structures have been found in a number of other proteins associated with the regulation of transcription in mammalian and yeast cells. * It is thought that this structure allows two identical monomers or heterodimers (eg, Fos-Jun or Jun-Jun) to "zip together" in a coiled-coil and form a tight dimeric complex *This protein-protein interaction may serve to enhance the association of the separate DNA binding domains with their target <img class="fr-dib" style="width: 300px;" src=" /> Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 574


Question: Bicarbonate moves out of RBC in peripheral tissues in exchange for

Unlike carbon dioxide, bicarbonate is very soluble in the blood plasma and therefore must return thereby moving out of the red blood cell. However, as it moves across the membrane, a chloride ion is brought into the cell. This is known as the chloride shift and it takes place in order to maintain electric neutrality. Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 197-200


Question: After digestion by restriction endonucleases, DNA strands can be joined again by

In mammals, after many Okazaki fragments are generated, the replication complex begins to remove the RNA primers, to fill in the gaps left by their removal with the proper base-paired deoxynucleotide, and then to seal the fragments of newly synthesized DNA by enzymes referred to as DNA ligases. DNA ligase Seals the single strand nick between the nascent chain and Okazaki fragments on the lagging strand.Ref.: Harpers Illustrated Biochemistry; 30th edition; page no: 383


Question: In starvation, glucose is mainly utilized as metabolic fuel by

In the fasting state, as the concentration of glucose in the poal blood coming from the small intestine falls, insulin secretion decreases, and skeletal muscle and adipose tissue take up less glucose. The increase in secretion of glucagon by a cells of the pancreas inhibits glycogen synthetase and activates glycogen phosphorylase in the liver leading to glycogenolysis. The resulting glucose-6-phosphate is hydrolyzed by glucose 6-phosphatase, and glucose is released into the bloodstream for use by the brain and erythrocytes. Reference: Harper; 30th edition; Chapter 14; Page no: 148


Question: High energy phosphate compounds are

Adenosine triphosphate, coenzyme used as an energy carrier in the cells of all known organisms; the process in which energy is moved throughout the cell


Question: Not a marker for muscle tumor

Markers for smooth muscles tumor are : (t) Muscle specific actin, (ii) Intermediate filament, and (iii) Desmin. Neurofilament is a marker of neural tumors.


Question: Promoter sequence is an example for

Trans acting factors control the expression of cis-regulatory element Cis-regulatory elements are DNA sequences present on the same molecule of DNA (chromosome) as the gene they regulate. E.g. Promoter is a cis-regulated element usually located upstream of the transcribed region. Enhancers are cis-regulatory elements that can be located upstream, downstream, within the introns,


Question: Regan isoenzyme is increased in

The Regan isoenzyme is a placental-type alkaline phosphatase that is expressed in a number of human tumors, paicularly in gonadal and urologic cancers. Evidence now points to seminoma as a consistent producer of Regan isoenzyme although much more work will be required to establish its clinical utility. Ref:


Question: Choose the major fuel that is being used by the brain after 1 day of fasting.

Production of ketone bodies by the livera. As glucagon levels rise, adipose tissue breaks down its triacylglycerol stores into fatty acids and glycerol, which are released into the blood.b. Through the process of b-oxidation, the liver converts the fatty acids to acetyl coenzyme A (acetyl CoA).c. Acetyl CoA is used by the liver for the synthesis of the ketone bodies, acetoacetate and b-hydroxybutyrate. The liver cannot oxidize ketone bodies and hence releases them into the blood.Blood glucose is the major fuel for the brain, except when, after 3 to 5 days of fasting, ketone bodies in the blood reach a concentration at which the brain can begin to utilize them. Even at this point the nervous system still obtains 60% of its energy from glucose. The brain does not take up, to an appreciable extent, fatty acids, and fatty acid oxidation does not provide much energy for the brain. The brain's glycogen stores are very small, and alanine is not used as an energy source under any conditions by the nervous system.


Question: The role of vitamin K in epoxide cycle is

Carboxylation of glutamate is the role of VitK in epoxide cycle. Vitamin K is necessary for coagulation. Factors dependent on vitamin K are Factor II (prothrombin); Factor VII (SPCA); Factor IX (Christmas factor); Factor X (Stua Prower factor) All these factors are synthesized by the liver as inactive zymogens. They undergo post-translational modification; gamma-carboxylation of glutamic acid residues. These are the binding sites for calcium ions. The gamma-carboxy glutamic acid (GCG) synthesis requires vitamin K as a co-factor Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 462 image satyanarayana 4th ed page 131


Question: Home to bilirubin conversion is carried out by

Within the macrophage, heme derived from haemoglobin is broken down by heme oxygenase, conveing it to biliverdin Carbon monoxide and iron arereleased as by-productsReference: Harper biochemistry 30th edition page no 672


Question: Vitamin K dependent clotting factor is

Vitamin K dependent clotting factors (VKCF) are clotting factors II (prothrombin), VII (Proconvertin), IX (Christmas factor), X (Stuart Prover Factor), protein C, protein S and protein Z.


Question: Substrate level phosphorylation in glycolysis is seen in

Step 9 of Glycolysis i. Phosphoenol pyruvate (PEP) is dephosphorylated to pyruvate, by pyruvate kinase. First PEP is made into a transient intermediary of enol pyruvate; which is spontaneously isomerized into keto pyruvate, the stable form of pyruvate. ii. One mole of ATP is generated during this reaction. This is again an example of substrate-level phosphorylation (Fig. 9.13). iii. The pyruvate kinase is a key glycolytic enzyme. This step is irreversible. The reversal, however, can be brought about in the body with the help of two enzymes (pyruvate kinase and phosphoenolpyruvate carboxykinase) and hydrolysis of 2 ATP moleculesRef: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 96


Question: Keratin of skin and nail differ because

Keratins - Keratins are proteins present in hair, skin and nails, horn, hoof, etc. The fibers present are called alpha keratins and matrix as keratohyalin. They mainly have the alpha helical structure. Each fibril has 3 polypeptide chains and each bundle has about 10-12 fibrils. The keratohyalin matrix has cysteinerich polypeptide chains which are held together by disulfide bonds. The more the number of disulfide bonds, the harder the keratin is. REF: DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY,EIGHTH EDITION,PG.NO.,674.


Question: DNA repair defects are seen in

Xeroderma pigmentosa is autosomal recessive conditionMutation in any one of the gene XP leads to dis conditionUv light causes the formation of thymine dimers where covalent bonds are formed between thymine residues Ref: DM Vasudevan, 7th edition, page no: 584, 584


Question: Defect in SNURPs causes

Spliceosomes : Small nuclear RNA (snRNAs) takes pa in formation of spliceosomes. All of them located in nucleus. They complex with specific proteins, to form smal nuclear ribonucleoprotein pacles (SnRNPs) REF : DM VASUDEVAN TEXTBOOK ; 8th EDITION ; Page no:573

Defect in terminal addition of nucleotide


Question: The common feature of Nuclear Localization Signals is

Many nuclear proteins contain NLSs that are rich in basic arginine and lysine residues, which may be located anywhere in the polypeptide chain. Reference: Harper; 30th edition

They are rich in acidic amino acid residues and are located at the C-terminus of the protein

They are rich in basic amino acid residues and are located at the C-terminus of the protein

They are rich in acidic amino acid residues and may be located anywhere in the protein sequence

They are rich in basic amino acid residues and may be located anywhere in the protein sequence


Question: Southern blot is used to visualize

A Southern blot is a method used in molecular biology for detection of a specific DNA sequence in DNA samples. Southern blotting combines transfer of electrophoresis-separated DNA fragments to a filter membrane and subsequent fragment detection by probe hybridization. Ref-D.M.Vasudevan 7/e p546


Question: Complimentary sequence of 5' GCACC 3'

Ans: d (5' GGTGC 3') Ref: Lippincott 3rd ed/p. 395.Adenine (A) always pairs with Thiamine (T).There are 2 Hydrogen bonds between A and T.Cytosine(C) always pairs with Guanine (G).There are 3 Hydrogen bonds between C and G.Complementary sequence of 5'-3' end always proceeds from 3'-5'.Therefore,5'GCACC 3' Complements 3'CGTGG 5'This can also be rewritten in 5' - 3' as5' GGTGC 3'


Question: A segment of a eukaryotic gene that is not represented in the mature mRNA, known as

The primary transcript are very long, they have molecular weights more than 10^7The primary transcript contains coding regions -extrons and non-coding regions -intronsThe introns sequence are cleaved and the exons are spliced to form mature mRNA moleculeRef: DM Vasudevan, 7th edition, page no: 591


Question: Cell shape and motility are provided by

Microtubules are polymers of tubulin that form pa of the cytoskeleton and provide structure and shape to cells


Question: Karyotyping under light microscopy is

B i.e. G banding [Ref: Nagesh Rao: Human genetics


Question: Different sequence of amino acids having similar structure of proteins is an example of

Ans. is 'b' i.e. Convergence Divergence and convergence are two evolutionary processes by which organisms become adapted to their environments.Convergence has been defined as the acquisition of morphologically similar traits between distinctly unrelated organisms.Convergence occurs at every level of biological organization.Functional ConvergenceThis refers to molecules that serve the same function but have no sequence or structural similarity and carry out their function by entirely different mechanisms.Mechanistic convergenceMechanistic convergence occurs when the sequence and structure of molecules are very different but the mechanisms by which they act are similar.Structural ConvergenceThis refers to molecules with very different amino acid sequences that can assume similar structural motifs, which may carry out similar functions.Sequence ConvergenceIn sequence convergence, one or more critical amino acids or an amino acid sequence of two proteins come to resemble each other due to natural selection. (In protein evolution, sequence divergence, rather than sequence convergence is the rule.)

Enzyme Specificity and Allosteric Regulation


Question: At physiological pH buffering action in the blood is caused by

Maximal buffering capacity occurs at pH equal to pKa of the buffer.
Therefore, to work as the best buffer at physiological pH amino acid should have pKa value close to physiological pH (7.4).
Amino acids can have buffering action due to three ionizable groups:-

α-carboxyl group:- Different amino acids have pKa value of α-carboxyl group between 3.5-4. So, the carboxyl group of amino acids has maximum buffering capacity between pH 3.5-4.
α-amino group:- Different amino acids have pKa value of α-amino group between 8.0-9.0. Thus, the α-amino group has maximum buffering capacity between pH 8.0-9.0.
Special ionizable group (in some amino acids):- Among the special ionizable group of amino acids, imidazole group of histidine has pKa value 6.5-7.4, which is closest to physiological pH. Hence, histidine (due to imidazole group) has maximum buffering capacity at physiological pH.


Question: The gaps between segments of DNA on the lagging strand produced by restriction enzymes are rejoined sealed by

RNA primer is excised by DNA polymerase I creating a gap between okazaki fragments which is filled by DNA polymerase I only, and remaining nick is sealed by DNA ligase.


Question: Translation occurs in


Question: The conjugation of bilirubin to glucuronic acid in the liver;

Ans. is 'b' i.e. converts a hydrophobic compound to a hydrophilic one.Ref: Harrison 16th/e p 239 (15th/e p 255)Bilirubin is produced in the reticuloendothelial cells of spleen and liver. This unconjugated bilirubin is not soluble in water so is bound to albumin for its transfer in plasma.Liver uptakes this unconjugated bilirubin and conjugates it with glucuronic acid generating bilirubin glucuronide which is water soluble.For more on this topic see Question no. 12 Nov. 1999

Converts a hydrophilic compound to a hydrophobic one

Converts a hydrophobic compound to a hydrophilic one

Enables the bilirubin molecule to cross the cell membrane


Question: Adenine in DNA binds with


Question: Okazaki fragment

The small DNA molecules attached to its own primer RNA are called Okazaki fragments The synthesis along the lagging strand is in 5&;-3&; direction As it moves, the primers synthesizes sho RNA primer to which deoxynucleotides are added by DNA polymeraseRef: DM Vasudevan, 7th edition, page no: 581


Question: Acyl carrier protein (ACP) occurs in a bound state to a derivative of the following vitamin

Vitamin FunctionsDeficiency DiseasePantothenic acid The functional pa of CoA and acyl carrier protein: fatty acid synthesis and metabolismPeripheral nerve damage (nutritionalmelalgia or "burning foot syndrome")Ref: Harper&;s biochemistry; 30th edition; Chapter 44 Micronutrients: Vitamins & Minerals


Question: Rate controlling enzyme of fatty acid synthesis

Carboxylation of Acetyl CoA The first step in the fatty acid synthesis is the carboxylation of acetyl CoA to form malonyl CoA. The acetyl CoA carboxylase is not a pa of the multienzyme complex. But it is the rate-limiting enzyme. Biotin, a member of B complex vitamins, is necessary for this reaction (step 1 in Fig. 11.15). The enzyme is allosterically regulated, the major effectors being citrate (positive) and palmitoyl CoA (negative). The reaction is similar to carboxylation of pyruvate to form oxaloacetate. The elongation of the fatty acid occurs by addition of 2 carbon atoms at a time. But the 2-carbon units are added as 3-carbon, malonyl units. The whole reaction sequence occurs while the intermediates are bound to ACP (acyl carrier protein).Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 137


Question: Pentose pathway is essential for the production of

The major metabolic role of the HMP shunt pathway is to provide cytoplasmic NADPH for reductive biosynthesis of fatty acids, cholesterol, and steroidsRef: DM Vasudevan, 7th edition, page no: 130


Question: Restriction fragment length polymorphism is used for

RFLP can be observed by cleaving the DNA into fragments with restriction enzymes. The length of the restriction fragments is altered if the genetic variant alters the DNA. It doesnot estimate DNA but detects variation in DNA structure. DNA is contained in chromosomes. RFLP also used to trace chromosomes from parents to offspring.


Question: Principle function of cyanocobalamine is

The principle function of cyanocobalamine is coenzyme for one carbon transfer in nucleic acid metabolism. When the methyl group replaces the adenosyl group, it is known as methylcobalamin. This is the major form seen in blood circulation as well as in the cytoplasm of cells. Tetrahydrofolate is mostly trapped as N5-methyl THF in which form it is present in the circulation. Vitamin B12 is needed for the conversion of N5-methyl THF to THF, in a reaction wherein homocysteine is conveed to methionine. This step is essential for the liberation of free THF and for its repeated use in one-carbon metabolism. In B12 deficiency, conversion of N5-methyl THF to THF is blocked Ref: satyanarayana 4th ed page 151

Post translational carboxylation of protein

Acts as coenzymes for methionine synthase and L methyl melonyl CoA synthase

A coenzyme for one carbone transfer in nucleic acid metabolism

A cofactor for decarboxylase of ketoacid


Question: Total numbers of codons are

Twenty different amino acids are required for the synthesis of the cellular complement of proteins; thus, there must be at least 20 distinct codons that make up the genetic code. Since there are only four different nucleotides in mRNA, each codon must consist of more than a single purine or pyrimidine nucleotide. Codons consisting of two nucleotides each could provide for only 16(42 )-distinct codons, whereas codons of three nucleotides could provide 64(43 )-specific codons. It is now known that each codon consists of a sequence of three nucleotides; that is, it is a triplet code (see Table 37-1). The initial deciphering of the genetic code depended heavily on in vitro synthesis of nucleotide polymers, paicularly triplets in repeated sequence. This synthetic triplet ribonucleo- tides were used as mRNAs to program protein synthesis in the test tube, and allowed investigators to deduce the genetic code.Ref: Harpers Illustrated Biochemistry, 30th edition, page no: 414


Question: Gene duplication plays an impoant role in the evolution of

Analysis of the human genome suggests novel genes created by retroposition may play an impoant role in primate evolution. However, data from non-human primates is still scarce. A comprehensive comparison was thus performed among four primate genomes (human, chimpanzee, orangutan, and macaque), which detects elevated rates of retroposition in both the common ancestor of hominoids and macaques. Fuher analysis shows approximately 10% of intact retrocopies may be under positive selection and at least 4% of retrocopies become functional copies eventually. Moreover, human intact retrocopies were found enriched in transcription-related functions. Collectively, these findings emphasize the impoant contribution of retroposition to primate genome evolution


Question: Western Blot detects

In this technique, proteins are identified Proteins are isolated from the tissue and electrophoresis is done Separated protein are then transferred on to nitrocellulose membrane After fixation, it is probed with radioactive antibody and autoradiographedRef: DM Vasudevan, 7th edition, page no: 634


Question: Protein di sulphide isomerase is involved in

Disulfide bonds between and within polypeptides stabilize teiary and quaternary structures. However, disulfide bond formation is nonspecific. Under oxidizing conditions, a given cysteine can form a disulfide bond with the --SH of any accessible cysteinyl residue. By catalyzing disulfide exchange, the rupture of an S--S bond and its reformation with a different paner cysteine, protein disulfide isomerase facilitates the formation of disulfide bonds that stabilize a protein&;s native conformationPeptidyl cis-trans isomerase, protein disulphide isomerase and chaperones are involved in protein folding


Question: A segment of a eukaryotic gene that is not represented in the mature messenger RNA is known as

The primary transcript contains introns & exons. Splicing removes introns (segment of the gene that is not represented in mature m-RNA) from primary transcript.


Question: The most essential fatty acid is

Linoleic acid

Linoleic acid is the most important essential fatty acid because it serves as a basis for the production of other EFA like arachidonic acid.


Question: Number of ATP formed per turn of citric acid cycle is

TEN ATP ARE FORMED PER TURN OF THE CITRIC ACID CYCLE As a result of oxidations catalyzed by the dehydrogenases of the citric acid cycle, three molecules of NADH and one of FADH2 are produced for each molecule of acetyl-CoA catabolized in one turn of the cycle. These reducing equivalents are transferred to the respiratory chain, where reoxidation of each NADH results in the formation of ~2.5 ATP, and of FADH2, ~1.5 ATP. In addition, 1 ATP (or GTP) is formed by substrate-level phosphorylation catalyzed by succinate thiokinase. Reference: Harper; 30th edition; Page no: 164


Question: End product of glycolysis in RBC is

Under anaerobic conditions, the NADH cannot be reoxidized through the respiratory chain, and pyruvate is reduced to lactate catalyzed by lactate dehydrogenase. This permits the oxidization of NADH, permitting another molecule of glucose to undergo glycolysis. Under aerobic conditions, pyruvate is transpoed into mitochondria and undergoes oxidative decarboxylation to acetyl-CoA then oxidation to CO2 in the citric acid cycle. Glycolysis in erythrocytes always terminates in lactate, because the subsequent reactions of pyruvate oxidation are mitochondrial, and erythrocytes lack mitochondria. Reference: Harper; 30th edition; Page no: 171


Question: Enzyme deficiency in Natowicz syndrome is

Disease name Abbretion Enzyme Defective GaG(s) affected Symptoms Natowicz syndrome MPS IX Hyaluronidase Hyaluronic acid Joint pain, sho stature Reference: Harper; 30th edition; Page no:639; Table: 50-8


Question: A respiratory quotient of 0.7 means

Respiratory Quotient (RQ) i. Respiratory quotient is defined as the ratio of volume of CO2 produced in L/g to the oxygen consumed in L/g. ii. RQ of carbohydrates is 1; RQ of fats is 0.7; that of proteins is 0.8 For a mixed diet it is between 0.7 and 1, often around 0.82-0.85. When the rate of utilization of fat increases in relation to carbohydrates, RQ falls. This happens in diabetes mellitus when utilization of carbohydrate is reduced. The RQ is lowest when ketolysis is very active. iv. The energy produced is approximately equal to 20 kJ/L of oxygen for all metabolic fuels (Table 36.1, last column).Ref: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 432


Question:
Barbiturate precipitates symptoms of porphyria
because


Question: The transmembrane region of a protein is likely to have

Some of the integral membrane proteins span the whole bilayer and they are called transmembrane proteins (Fig. 2.4). The hydrophobic side chains of the amino acids are embedded in the hydrophobic central core of the membrane. The transmembrane proteins can serve as receptors (for hormones, growth factors, neurotransmitters), tissue-specific antigens, ion channels, membrane-based enzymes, etc.Ref: DM Vasudevan, page no: 12

Alternating hydrophilic and hydrophobic amino acids


Question: Ribosome has following enzymatic activity

The Peptidyl transferase is an aminoacyltransferase as well as the primary enzymatic function of the ribosome, which forms peptide bonds between adjacent amino acids using tRNAs during the translation process of protein biosynthesis.In Prokaryotes, the 50S (23Scomponent) ribosome subunit contains the peptidyl transferase component and acts as a ribozyme.In Eukaryotes, the 60S (28Scomponent) ribosome subunit contains the peptidyl transferase component and acts as the ribozyme.


Question: Cytoplasmic process during processing is


Question: The initiation of DNA synthesis requires

The initiation of DNA synthesis requires priming by a sho length of RNA, about 10 to 200 nucleotides long. In E coli this is catalyzed by dnaG (primase), in eukaryotes, DNA Pol a synthesizes these RNA primers. Harper30e pg: 383


Question: Restriction endonuclease cleaves

Restriction endonuclease Cleaves double stranded DNA at palindromic sites/ restriction sites 5' --AAGCTT-- 3'3' --TTCGAA-- 5' A palindromic sequence is a sequence which reads the same backwards as forwards. Found in bacteria Can create sticky ends or blunt ends Restriction endonuclease Sticky ends Blunt ends single-stranded overhangs no overhangs Example - EcoRI Example -SmaI


Question: Conversion of fat to glucose is

Ans: c (gluconeogenesis) Ref: Vasudevan 4th ed/p.92.Gluconeogenesis is the process by which new glucose is synthesised from non-carbohydrate precursors.Substrates for gluconeogenesis are:-i) Gluconeogenic amino acids - Alanine is the major gluconeogenic amino acid, all but Leucine and Lysine, are gluconeogenicii) Lactate (from anaerobic glycolysis)iii) Glycerol 3- phosphate (from TAG in adipose) minor sourceiv) Propionyl CoA from odd chain fatty acids - minor source PFK = Phospho fructokinaseDHAP = dihydroxy acetone phosphatePEP = phosphoenol pyruvatePEPCK = phosphoenol pyruvate carboxykinaseOAA = OxaloacetoacetatePDH = Pyruvate dehydrogenaseReversible enzymes:i) Glyceraldehyde 3P Dehydrogenaseii) Phosphoglycerate kinaseiii) Mutaseiv) EnolaseIrreversible enzymes:i) Pyruvate carboxylase - mitochondrial enzymeii) Phosphoenol pyruvate carboxykinase - cytoplasmiii) Fructose 1,6- bisphosphate - cytoplasmiv) Glucose- 6-phosphate - endoplasmic reticulum


Question: Source of energy in Kreb cycle is

TCA / Krebs cycle Characteristics of TCA cycleuSite of occurrence - Mitochondria u20 ATPs are produced in one cycleuAmphibolic pathway (Anabolic + Catabolic pathway)uAnaplerotic reaction of TCA cycle - Pyruvate to Oxaloacetate by Pyruvate carboxylase Inhibitors Enzyme Inhibitor Aconitase Fluoroacetate Alpha ketoglutarate Arsenite Succinate dehydrogenase Malonate Irreversible reactions Reactions Enzyme Oxaloacetate - Citrate Citrate synthase Alpha ketoglutarate - Succinyl Co-AAlpha ketoglutarate dehydrogenase Oxidative / Substrate level phosphorylation Reactions Enzyme Succinyl Co-A - Succinate Succinate thiokinase Energetics 20 ATPVitamins in TCA cycle Riboflavin Niacin Thiamine Pantothenic acid FAD as cofactor NAD as cofactor Thiamine diphosphate as cofactor Coenzyme A as cofactor Alpha ketoglutarate dehydrogenase;Succinate dehydrogenase Isocitrate dehydrogenase;Alpha ketoglutarate dehydrogenase; Malate dehydrogenase Alpha ketoglutarate dehydrogenaseAcetyl CoA; Succinyl CoAHarper's illustrated Biochemistry , 30th ed , page 164


Question: One of the following is considered to be the key regulatory enzyme of glycolysis

Phosphofructokinase is both inducible and subject to allosteric regulation and has a major role in regulating the rate of glycolysis.These reactions, catalyzed by hexokinase (and glucokinase), phosphofructokinase, and pyruvate kinase, are the major sites of regulation of glycolysis.Phosphofructokinase is considered key regulator.Harper 30th edition pg: 172


Question: Basic amino acids are

(Lysine and Arginine) (47- U.Satyanarayan 3rd)Classification of Amino acids1.Amino acid with aliphatic side chains - Glycine, Alanine, valine, leucine and Isoleucine2.Hydroxyl group containing amino acids- Serine, threonine and tyrosine3.Sulfur containing amino acids - cysteine, methionine4.Acidic ami noacids - Aspartic acid, glutamic acid5.Basic amino acids - Lysine, arginine, histidine6.Aromatic amino acids - Phenyl alanine, tyrosine and tryptophan7.Imino acids - Proline


Question: Refsum's disease is due to accumulation of

Refsum disease is a rare neurologic disorder due to a metabolic defect that results in the accumulation of phytanic acid, which is found in dairy productsand ruminant fat and meat. Phytanic acid is thought to have pathological effects on membrane function, protein prenylation, and gene expression.Ref: Harper&;s Biochemistry; 30th edition; Chapter 22; Oxidation of Fatty Acids: Ketogenesis


Question:
In response to change in pH, increase glutaminase
activity is due to


Question: Edman's reagent is

Ans. is 'c' i.e., Phenyl-isocyanateDetermination of amino acid sequence (sequence analysis) is performed by Edman degradation method on automatic mechines, called cyclic sequentors. Edman's reagent is phenyl-isothiocyanate, and forms a covalent bond to N-terminal of amino-acid. This can be identified.Sanger's reagent (1-fluoro-2,4-dinitrobenzene) can be used in place of Edman's reagent.


Question: Post translational modification of hydroxylysine and hydroxyproline is by

Ans: a (Vit C) Ref: Vasudevan 4th ed/p.415Post translational modification:-* Gamma carboxylation of glutamic acid residues of prothrombin under the influence of vitamin K.* Hydroxylation of proline and lysine in collagen with the help of Vitamin C* C- terminal amidation and cyclisation of N-terminal amino acid of TRH* Phosphorylation of hydroxyl groups of serine, threonine or tyrosine by kinases.eg. glycogen phosphory- laseCotranslational glycosylation, whereby carbohydrates are attached to serine or Threonine residues* Methylation of lysine, Histidine and Arginine residues eg. Histones* Acylation eg.myelin proteolipid or transferring receptor.Post transcriptional modification:-* 5' capping: - this is the first of the processing reactions for hn RNA. 7-methyl guanosine is attached 'backwards' to the 5' terminal of the mRNA. This serves to stabilise the mRNA.* Addition of poly-A tail (3' polyadenylation): About 40-200 adenine are attached to the 3' end of the mRNA. These tails help to stabilize the mRNA and facilitate its exit from the nucleus. After mRNAenters the cytosol, the poly-A tail is gradually shortened.Removal of introns (splicing):- Introns or intervening sequences that do not code for protein are removed. This splicing occurs in the nucleus and serves to bring the exons together. After removal of the introns, the mature mRNA molecules leave the nucleus.


Question: The energy for glycogenesis is provided by

UDP glucose is formed from glucose-1-phosphate and UTP (uridine triphosphate) by the enzyme UDP-glucose pyrophosphorylase. UDP-glucose pyrophosphorylase Glucose-1- --------------- UDP-glucose phosphate +UTP + PPiRef: DM Vasudevan, 7th edition, page no: 125


Question: Glutamine in blood acts as

Glutamine is the major transport form of ammonia.


Question: Thymidylated RNA present in

The only RNA which contains thymidine (ribothymidine) is tRNA.


Question: Nyctalopia is due to deficiency of


Question: Rough endoplasmic reticulum is the site of synthesis for

Rough endoplasmic reticulum is concerned with Protein synthesis*
Initial folding of the polypeptide chains with the formation of disulfide bonds Smooth endoplasmic reticulum is concerned with Steroid synthesis
* Detoxication processes As sarcoplasmic reticulum plays important role in skeletal and cardiac muscle contraction *


Question: First product of purine metabolism

Humans catabolize purines to uric acid. But, first purines are catabolized to xanthine, which is fuher catabolized to purine.


Question: Phenylketonuria caused by deficiency of

(C) Phenyalanine hydroxylase # Phenylketonuria is a genetic disorder inherited from a person's parents.> It is due to mutations in the PAH gene which results in low levels of the enzyme phenylalanine hydroxylase.> This results in the build up of dietary phenylalanine to potentially toxic levels. It is autosomal recessive meaning that both copies of the gene must be mutated for the condition to develop.> There are two main types, classic PKU and variant PKU, depending on if any enzyme function remains.> Those with one copy of a mutated gene typically do not have symptoms.


Question: Serum gamma glutamyl transpeptidase maximum increased in

A. i.e. (Alcoholism) (107- U. Satyanarayan 3rd) (600- Rana -Shinde 7th)Important enzymes in the diagnosis of disease* SGPT / ALT- Liver disease (Hepatitis)* SGOT/AST- MI & Liver disease* LDH- MI, Infective hepatitis* CPK- Myocardial infarction* Aldolase- Muscular dystrophy* 5 - Nucleotidase- Hepatitis* Y- Glutamyl- transpeptidase (GGT)- Alcoholism* Y- GT is the most sensitive indicator in alcoholism* Useful test for MI in later stages* Increase serum activity seen with pancreatic disease* It is a valuable parameter in differentiating between skeletal (bone) and hepatic dysfunction associated withincreased serum ALP


Question: The buffering capacity of a buffer is maximum at pH equal to

The pH of a buffer is determined by the Henderson-Hasselbalch equation So, at the max buffering capacity, = . This is because a buffer reacts in the following manner--it is able to buffer against equal amounts of acid (H+) or base (OH-) added. A- + H+ - HA HA + OH- - H2O + A- Finally, we can see from the above Henderson-Hasselbalch equation that when = , pH = pKa.


Question: Ketosis is caused by

KETOSISNormally the rate of synthesis of ketone bodies by the liver is such that they can be easily metabolised by the extrahepatic tissues. Hence the blood level of ketone bodies is less than 1 mg/dl and only traces are excreted in urine (not detectable by usual tests).But when the rate of synthesis exceeds the ability of extrahepatic tissues to utilise them, there will be accumulation of ketone bodies in blood.This leads to ketonemia, excretion in urine (ketonuria) and smell of acetone in breath. All these three together constitute the condition known as ketosis.Causes for KetosisDiabetes Mellitus: Uncontrolled diabetes mellitus is the most common cause for ketosis. Even though glucose is in plenty, the deficiency of insulin causes accelerated lipolysis and more fatty acids are released into circulation. Oxidation of these fatty acids increases the acetyl CoA pool. Enhanced gluconeogenesis restricts the oxidation of acetyl CoA by TCA cycle since the availability of oxaloacetate is less.Starvation: In starvation, the dietary supply of glucose is decreased. Available oxaloacetate is channeled to gluconeogenesis. The increased rate of lipolysis is to provide alternate source of fuel. The excess acetyl CoA is conveed to ketone bodies. The high glucagon level ors ketogenesis. The brain derives 60-75% of energy from ketone bodies under conditions of prolonged starvation. Hyperemesis (vomiting) in early pregnancy may also lead to starvation-like condition and may lead to ketosis.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 144


Question: The predominant isozyme of LDH in cardiac muscle is

In myocardial infarction, total LDH activity is increased, while H4 iso-enzyme ( monomer of LDH ) is increased 5-10 times more. The magnitude of the peak value, as well as the area under the graph, will be roughly propoional to the size of the myocardial infarct. Ref: D M Vasudevan 7th edition Page no: 304


Question: Sulphur containing amino acid is/are

Based on the chemical structure of side chain (R), amino acids are classified into:-

1) Aliphatic amino acids:- Alanine, glycine, isoleucine, leucine, valine.
2) Hydroxy amino acids:- Serine, threonine, tyrosine.
3) Sulfur containing amino acids:- Cysteine, methionine.
4) Dicarboxylic amino acids:- Aspartic acid (aspartate), glutamic acid (glutamate).
5) Amide containing amino acids:- Glutamine, asparagine (these are amides of dicarboxylic amino acids.
Glutamine is amide of glutamic acid and asparagine is amide of aspartic acid).
6) Aromatic amino acids:- Phenylalanine, tyrosine, tryptophan.
7) Amino acids or heterocyclic amino acids: - One of the 20 amino acids, proline is an amino (- NH) acid, not an amino (-NH2) acid, as are other 19.


Question: The Second most important intracellular cation is

(A) Magnesium # MAGNESIUM is the second most important intracellular divalent cation and is involved in a variety of metabolic processes including glucose metabolism, ion channel translocation, stimulus-contraction coupling, stimulus secretion coupling, peptide hormone receptor signal transduction.> Normal concentrations of extracellular magnesium and calcium are crucial for normal muscular activity.


Question: Glucose transpo along cell membranes occurs along with

The co-transpo system may either be a sympo or an antipo. In sympo, (Fig. 2.12) the transpoer carries two solutes in the same direction across the membrane, e.g. sodium-dependent glucose transpoer (Chapter 8). Phlorhizin, an inhibitor of sodium-dependent co-transpo of glucose, especially in the proximal convoluted tubules of the kidney, produces renal damage and results in renal glycosuria. Amino acid transpo is another example for sympo.Ref: MN Chatterjea Textbook of Medical Biochemistry, 6th edition, page no: 17


Question: Ammonia formed in brain, is conveed into

The transpo form of Ammonia in blood and from Brain is Glutamine. Glutamine is Non-toxic form of storage and transpoation of ammonia in blood. In liver this ammonia is used for the production of urea.