Question: Composition of Hyaluronic acid

Composition of hyaluronic acid: repeating units of N-Acetyl-glucosamine and beta-1,4-Glucuronic acid.Ref: DM Vasudevan, 7th edition, page no: 80

N-acetyl glucosamine + b glucosamine acid

N-acetyl glucosamine + b-glucoraunic acid

N-acetyl glucosamine + sulfated glucosamine acid


Question: Xylitol is a


Question: Von Gierke&;s disease is due to the deficiency of

Glycogen storage disease type I (GSD I) or von Gierke&;s disease, is the most common of the glycogen storage diseases. This genetic disease results from deficiency of the enzyme glucose-6-phosphatase and has an incidence in the American population of approximately 1 in 100,000 bihs.Ref: DM Vasudevan, 7th edition, page no: 128


Question: In Hanup&;s disease ..... is excreted in the urine

Hanups disease is an autosomal recessive disease. Absorption of aromatic amino acids, as well as reabsorption from renal tubular, are defective. So amino acids are tryptophan excreted in urine.pellagra-like symptoms due to niacin derived from tryptophan. Diagnosis: ober Meyer test (based on aminoaciduria)Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 242


Question: In the entire genome, the exonic DNA constitutes

Human genome: Size: 3 billion base pairs Number of genes: <25,000 At least 30% of the genome consists of repetitive sequences Alu family constitutes ~10% of human genome Largest gene: DMD gene coding for dystrophin protein Only around 1.5 % of human genome is made of protein-coding (exonic) DNA


Question: Total number of base pairs in human haploid set of chromosome

Humanhaploid genome of each cell consist of (3*109 ) bp (3 billion bp)Current estimates predict 20,687 protein coding genes Exome constitutes 7.74% of genomeSNPs estimated is 10 million.


Question: Essential pentosuria is due to deficiency of


Question: FIGLU excretion test is to estimate deficiency of


Question: Conversion of Pyruvate to Acetyl CoA does not require

Pyruvate is conveed to acetyl CoA by oxidative decarboxylation catalysed by a multienzyme complex, known as pyruvate dehydrogenase complex (PDH) The enzyme PDH requires five cofactors (coenzymes), namely--TPP(thiamine pyrophosphate), lipoamide, FAD, coenzyme A and NAD+ ref Satyanarayana biochemistry 4th ed page 252


Question: Protein degradation occurs in

Glycoproteins are generally transpoed fron ER to cis Golgi , then to medial Golgi and finally ti trans golgi for temporary storage. Trans Golgi is paicularly abundant with vesicles containing glycoproteins. Newly synthesized proteins are soed first according to the soing signals available in the proteins. Main function of Golgi apparatus is protein soing, packaging and secretion. Reference : DM.VASUDEVAN TEXTBOOK SEVENTH EDITION ; PAGE NO .12


Question: Hb saturation with oxygen is mostly dependent on

Increased pH (decreased H+), decreased temperature, decreased PaCO2, and decreased 2,3-DPG will increase oxygen binding to the haemoglobin Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 198,199


Question: The aminoacid carboxylated by vitamin K is

Vitamin  K  acts as a coenzyme for the carboxylation  of glutamic  acid residues present in the proteins and this reaction is catalysed by  a  carboxylase (microsomal).
Ref : Satyanarayana, 3rd ed, pg 130


Question: Expected change in Vitamin B,2 deficiency

Ans. is 'b' i.e., Increased methylmalonic acid in urine Isomerization of methvlmalonyl CoA to succinyl CoAIn this reaction, active form of vitamin BI2 is deoxyadenosyl cobalamine.Propionyl-CoA is produced as catabolic end product of some alipathic amino acids andb-oxidation of odd chain fatty acids.Propionyl CoA is then conveed to succinyl CoA through methylmalonyl-CoA.Thus methylmalonyl-CoA is accumulated and excreted in urine as methylmalonic acid (methylmalonate) in vitamin B12 deficiency, i.e. methylmalonic aciduria.


Question: The primary defect in Xeroderrna pigmentosa is

In xeroderma pigmentos a; nucleotide excision repair of damaged DNA is defective due to formation of TT dimers


Question: Markers of plasma membrane are

Markers of plasma membrane areMarker enzyme for mitochondria is ATP SynthaseMarker enzyme for golgi complex is GalactosyltransferaseAdenylyl cyclase appears to be a good marker enzyme for plasma membranes5'-Nucleotidase (5NT) is an intrinsic membrane glycoprotein that is present as an enzyme in a wide variety of mammalian cells. It facilitates the hydrolysis of the phosphate group from 5'-nucleotides, resulting in corresponding nucleosides.


Question: Gene for folic acid absorption is present on


Question: Vitamin A activity is inhibited by

These results suggest that citral inhibits both the natural vitamin A in the plasma and the added synthetic vitamin A, thus producing changes in the tracheal epithelium characteristic of vitamin A deficiency.
Ref : The Effects of Vitamin A and Citral on Epithelial Differentiation in vitro, J. Embryol. exp. Morph., Vol. 11, Part 1, pp. 279-291


Question: Mucopolysaccharidoses are caused by

Mucopolysaccharides are excreted in urine in abnormal amounts in the group of lysosomal storage disorders known as mucopolysaccharidoses. They can be detected by 2D gel electrophoresis techniques; some mucopolysaccharides can also be detected by simple urine screening tests like CPC test, Cetavlon test and Alcian blue staining.Ref: D M Vasudevan 7th edition Page no: 80

An increased rate of synthesis of proteoglycans

Defects in the degradation of proteoglycans

The synthesis of polysaccharides with an altered structure

An insufficient amount of proteolytic enzymes


Question: NAD acts as a cofactor for

In the TCA cycle,Step 3. In the third step, isocitrate is oxidized and releases a molecule of carbon dioxide, leaving behind a five-carbon molecule--a-ketoglutarate. During this step, \text{NAD}^+NAD + N, A, D, sta superscript, plus, end superscript is reduced to form \text{NADH}NADHN, A, D, H. The enzyme catalyzing this step, isocitrate dehydrogenase, is impoant in regulating the speed of the citric acid cycle.Ref: DM Vasudevan, 6th edition, page no: 218


Question: 1st clinical sign of vitamin A deficiency is

Night blindness (nyctalopia) is  one  of  the  earliest symptoms  of  vitamin  A  deficiency.


Question: The following fatty acid does not belong to W6 series

D i.e. Alpha linolenic acidAlpha linolenic acid belongs to W3 seriesQ. Rest others belong to W6 series.Carbon atoms are numbered from the carboxyl carbon (carbon no. 1). The carbon atoms adjacent to carboxyl carbon are also called. a, 13, Y respectively. The terminal methyl carbon is K/as W or n- carbonW3 Family ,MILW6 FamilyW7 FamilyW9- Alpha linolenic Q- Gamma linolenicQPalmitoleic- 0 leicQ- Timnodonic- ArchidonicQ - Elaidic- Cervonic- LinolicQ - The first double bond introduced into a saturated fatty acid (to make it unsaturated) is nearly always in 49 position. The reaction is catalyzed by 49 desaturase in presence of 02, NADH and cytochrome b5.Since animals have 49 desaturase, they are able to synthesize W9 (oleic) family.- Linoleic (W6) or a - linolenic (W3) acids required for the synthesis of other members of W6 or W3 family must be supplied in diet.


Question: Null mutation is

Null mutation/loss of function mutation/amorphic mutations:- These mutations are the result of gene product having less or no function. It occurs when the allele has a complete loss of function. Phenotypes associated with such mutations are most often recessive.

Mutation that does not change the amino acid or end product

Mutation that codes for a change in progeny without any chromosomal change

Mutation that leads to no functional gene product


Question: Von gerke's disease is associated with


Question: Nucleotides are

Purines & Pyrimidines Are Heterocyclic Compounds.Nucleosides Are N-Glycosides.Nucleotides Are Phosphorylated Nucleosides .Ref: Harper&;s Biochemistry; 30th edition; Chapter 32; Nucleotides


Question: Source of ATP in RBC&;s is

Glycolysis is the only source of energy in erythrocytes. During anaerobic (oxygen deficient) condition, when one molecule of glucose is conveed to 2 molecules of lactate, there is a net yield of 2 molecules of ATP. 4 molecules of ATP are synthesized by the 2 substrate level phosphorylations (steps 6 and 9). But 2 molecules of ATP are used in the steps 1 and 3, hence the net yield is only 2 ATP (Table 9.4). The whole reaction is summarized as Glucose + 2 Pi + 2 ADP --> 2 Lactate + 2 ATPRef: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 93 & 96


Question: Severe muscular exercise causes

Intense Exercise. When you exercise, your body uses oxygen to break down glucose for energy. During intense exercise, there may not be enough oxygen available to complete the process, so a substance called lactate is made. Your body can conve this lactate to energy without using oxygen. But this lactate or <a href=" acid can build up in your bloodstream faster than you can burn it off. The point when lactic acid stas to build up is called the "lactate threshold."Inhibition of Pyruvate MetabolismLeads to Lactic AcidosisArsenite and mercuric ions react with the 'SH groups of lipoic acid and inhibit pyruvate dehydrogenase, as does a dietary deficiency of thiamin (see Chapter 44), allowing pyruvate to accumulate. Many alcoholics are thiamin deficient (both because of a poor diet and also because alcohol inhibits thiamin absorption), and may develop potentially fatal pyruvic and lactic acidosis. Patients with inherited pyruvate dehydrogenasedeficiency, which can be the result of defects in one or more of the components of the enzyme complex, also present with lactic acidosis, paicularly after a glucose load. Because of the dependence of the brain on glucose as a fuel, these metabolic defects commonly cause neurological disturbances. Inherited aldolase A deficiency and pyruvate kinase deficiency in erythrocytes cause hemolytic anaemia. The exercisecapacity of patients with muscle phosphofructokinase deficiency is low, paicularly if they are on high-carbohydrate diets. By providing lipid as an alternative fuel, for example, during starvation, when blood free fatty acid and ketone bodies are increased, work capacity is improvedReference: Harper biochemistry page no 174


Question: Amber codon is

Name of Stop codons: UAG - Amber codon UGA - Opal codon UAA - Ochre codon


Question: Homocystinuria is due to abnormal metabolism of

Homocystinuria is a group of disorder of methionine metabolism.


Question: Of the following groups of amino acids produce common component of the TCA cycle is


Question: The amino acids producing ammonia in kidney is

Transpoation of Ammonia : Inside the cells of almost all tissues , tge transamination of aminoacids produce glutamic acid . However, glutamate dehydrogenase is available is available only in liver . In kidney the ammonia is formed to Glutamine by the enzyme Glutamine synthetase. Ref : DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION ; PAGE NO : 203


Question: Activator of acetyl CoA carboxylase is

Acetyl CoA Carboxylase It is the key enzyme; citrate activates this enzyme. The citrate level is high only when both acetyl CoA and ATP are abundant. Covalent modification is another regulatory mechanism. Phosphorylation inactivates acetyl CoA carboxylase (similar to glycogen synthase under the effect of glucagon). Hence fatty acid synthesis decreases when glucose level is low. The enzyme is inhibited by palmitoyl CoA, the end product.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 139


Question: Ketoacidosis without glycosuria is seen in

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% ofenergy from ketone bodies under conditions of prolonged starvation. Hyperemesis (vomiting) in early pregnancy may also lead to starvation-likecondition and may lead to ketosis. The urine of a patient with diabetic ketoacidosis will give positive Benedict&;s test as well as Rothera&;s test. But instarvation ketosis, Benedict&;s test is negative, but Rothera&;s test will be positive.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 144 - 145


Question: Transport of the cholesterol from peripheral tissue to liver is through

(HDL): (5/7. U. Satyanarayan4th edition; 243-Lippincott's 6th)HDL particles transport cholesterol from peripheral tissues to the liver (reverse cholesterol transport)Concept map for cholesterol and the lipoproteins. HMG CoA = hydroxymethylglutaryl coenzyme A; SREBP = sterol regulatory element-binding protein; HDL = high-density lipoprotein; VLDL = very-low-density lipoprotein; LDL = low- density lipoprotein; TAG = triacylglycerol; NADP(H) = nicotinamide adenine dinucleotide phosphate.


Question: Ketone body formation without glycosuria is seen in

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 fuelExcess acetyl CoA is conveed to ketone bodies


Question: Transport form of iron is


Question: NADPH is required for

Fatty acid synthesis

Cofactor requirements for fatty acid synthesis include NADPH, ATP, Mn+2, biotin (a vitamin B) and HCO3- (as a source of CO2).
NADPH is also required for reductive synthesis of cholesterol and steroids.


Question: Molecular separation of two proteins with same charge can be done by

Molecular separation of two proteins with same charge can be done by gel diffusion chromatography. Gel diffusion chromatography is the best method to differentiate proteins. Ref: Harper 28th Ed. Page-21-22, Harper 27th Ed. Page: 21-22


Question: Protein fragments separation is/are done by

GEL FILTRATION CHROMATOGAPHY It is also called molecuar sieving .Hyrophilic cross linked gels are used for seperation of molecules based on their size. The gel is packed in a column . The gel paicles are porous in nature . These pores will allw small molecules to enter into the gel. But larger molecules could not enter into the pores of the gel and so are excluded. The small molecules can enter the gel paicles ,then come out,re-enter into the another paicle.Small molecules are held back.But large molecules cannot enter the pores and sidetrack the gel paicles; so they move in the column rapidly.In sho ,larger molecules will come out first, while smaller molecules are retained in the column. REFERNCE : DM VASUDEVAN TEXTBOOK EIGHTH EDITION ; Page no :435


Question: Long chain fatty acids penetrates in the inner mitochondrial membrane through

(Carnitine derivatives) (184-lIarper 28th)* Long chain fatty; acids penetrate the inner mitochondrial membrane as carnitine derivatives (184-Harper 28th)* The inner mitochondrial membrane is impermeable to fatty acids. A specialized carnitine carrier system (Carnitine shuttle) operates to transport activated fatty acids from cytosol to the mitochondria (288.U. Satyanarayan 3rd)* Inhibitor of carnitine shuttle is Malonyl CoATransport of long chain fatty acids (LCFA) in to mitochondriaAfter a LCFA enters a cell, it is converted in the cytosol to its CoA derivative by long chain fatty acyl CoA synthetase (thiokinase) an enzyme of the outer mitochondrial membrane. Because b-oxidation occurs in the mitochondrial matrix, the fatty acid must be transported across inner mitochondrial membrane which is impermeable to CoA. Therefore a specialized carrier transports the long chain acyl group from the cytsol into mitochondrial matrix. This carrier is carnitine and this rate limiting transport process is called the carnitine shuttle* Zellweger syndrome - is caused by the absence of peroxisomes in tissues as a result, the long chain fatty acids can not be oxidasedEntry of short and median chain fatty acids into the mitochondria (192-Lippincotf s 4th)* Fatty acids shorter than 12 carbons can cross the inner mitochondrial membrane without the aid of carnitine or the CPT system {carnitine palmitoyl transferase) once inside the mitochondria, they are activated to their CoA derivatives by matrix enzymes and are oxidized [Note- median chain fatty acids are plendiful in human milk. Because their oxidation is not dependent on CPT-1, it is not subject to inhibition by malonyl CoA)* Medium chain fatty acyl CoA dehydrogenase (MCAD) deficiency is one of the most common inborn errors of metabolism it causes decrease in fatty acid oxidation, resulting in hypoketonemia and severe hypoglycemiaImportant Points* Hormone sensitive lipase activity is inhibited by the hormone Insulin* Two final products in P-oxidation of odd chain fatty acids are- Acetyl coA andpropionyl coA* Maximum absorption of short chain fatty acids produced by bacteria occurs in the colon*** Absorption of long chain FA is greatest in the upper parts of the small intestine* Normal fecal fat excretion is less than 6gm/day more than 6 gm 24 hours indicates malabsorptions* Steatorrhea is defined as stool fat exceeding 7 gm/day* Sudan III is the best for screening but gold standard is quantitative estimation offecal fat* Esterified FA in the form of triacylglycerols serve as the major reserve of the body* Trans Fatty Acids - Classified as unsaturated fatty acids but behave more like saturated fatty acids in the body that is they elevate serum LDL and they increase the risk of CHD** & DM* TFA are formed during the hydrogenation of liquid vegetable oils** Fried foods*** Docosahexaenoid acid (DHA) is particularly needed for development of brain and retina and is supplied via the placenta and milk***


Question: Transamination of pyruvate with glutamate produces

Two most important transamination reactions are catalyzed by alamine transminase (ALT) and aspartate transaminase (AST).


Question: Ladder pattern of DNA electrophoresis in apoptosis is caused by the action of the following enzyme

1.Apoptosis progresses quickly and its products are quickly removed, making it difficult or visualize. 2.During karyorrhexis endonuclease activation leaves sho DNA fragments, regularly spaced in size. 3.this gives a characteristic laddered appearance on agar gel electrophoresis. 4.This laddered pattern is characteristic but not specific for apoptosis..It may seen in necrosis also. Ref Endonuclease. Robbins 7 th /edition, pg 26, 27and 28.


Question: Maximum influence of local milieu on ionization is on

Depending upon localized pH of its environment (local milieu), histidine can serve both proton donor and acceptor.


Question: The general test for detection of carbohydrates

Dehydration When treated with concentrated sulfuric acid, monosaccharides undergo dehydration with an elimination of 3 water molecules. Thus hexoses give hydroxymethyl furfural while pentoses give furfural on dehydration. These furfural s can condense with phenolic compounds (a-naphthol) to form coloured products. This is the chemical basis of the popular Molisch test. In case of oligo- and polysaccharides, they are first hydrolysed to monosaccharides by acid, and this is followed by dehydration. The test solution is combined with a small amount of Molisch's reagent (a-naphthol dissolved in ethanol) in a test tube. After mixing, a small amount of concentrated sulfuric acid is slowly added down the sides of the sloping test-tube, without mixing, to form a layer. A positive reaction is indicated by appearance of a purple red ring at the interface between the acid and test layers Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 17


Question: Thiamine is essential for

The  enzyme  pyruvate  dehydrogenase catalyses  (oxidative  decarboxylation)  the irreversible conversion of  pyruvate to  acetyl CoA. This reaction is dependent on thiamine pyrophosphate.


Question: Enzyme deficiency in Alkaptonuria is

B. i.e. (Homogentisate oxidase) (259 - Harper 27th)ALKAPTONURIA = lack of enzyme homogentisate oxidase enzyme most striking clinical manifestation - occurrence of dark urine black on standing in air*** Classical type Galactosemia - Galactose-1 p- uridyl transferase enzyme* Classical phenylketonuria - Phenyl alanine hydroxylase* Type I Tyrosinemia - Fumatyl acetoacetate hydrolase enzyme* Type II Tyrosinemia - Hepatic transaminase enzyme.


Question: TCA cycle does not take place in

Erythrocytes (RBC) lack mitochondria (so TCA cycle enzymes) and completely rely on glucose as their metabolic fuel. They metabolize it by anaerobic glycolysis.


Question: Cystinuria presents with excess of

Ans. (a) CysteineRef: Harper's Biochemistry 30th edn. 1301


Question: The following is due to deficiency of

Nyctalopia(Night blindness) is the earliest symptom of vitamin A deficiency Loss of sensitivity to green light(500nm) is the earliest sign of vitamin A deficiency Up to the level of Stage 2, the manifestations are reversible if treated with vitamin A supplements. However, active conjunctival xerosis and Bitot's spots begin to resolve within 2--5 days after supplementation. Most will disappear within 2 weeks, although a significant propoion of temporal lesions may persist in shrunken form and may therefore not be completely reversible. Reference: Harpers illustrated biochemistry 30th edition


Question: Glucose is linked to hemoglobin through

The glycated hemoglobins are together called HbA1 fraction.Out of this 80% molecules are HbA1c, where glucose is attached to the N -terminal valine of beta chain of hemoglobin. The rest of molecules are HbA1a1, where fructose 1,6-phospate and HbA1a2, where glucose-6-phosphate are attached. REF :DM VASUDEVAN TEXTBBOK ,7th EDITION; Page no :328


Question: Folding protein are

Calnexin is a chaperone, characterized by assisting protein folding and quality control, ensuring that only properly folded and assembled proteins proceed fuher along the secretory pathway.Ref: Harper&;s Illustrated Biochemistry, 26th edition, page no: 508


Question: Triglycerides are maximum in

Ans. is 'a' i.e. Chylomicrons [Ref: Chatterjee & Shinde Biochemistry 6/e, p 338 (T21.2); Harper 26/e, p 206;Maximum content of TG's is seen in - Chylomicrons*Maximum content of exogenous TG's is seen in - Chylomicrons*Maximum content of endogenous TG's is seen in - VLDL*Maximum cholesterol is seen in - LDL*Chylomicrons are the lipoprotein particles lowest in density and largest in size, and contains the highest percentage of lipids and the smallest percentage of proteins. VLDLs and LDLs are successively denser, having higher ratios of protein to lipid. HDL particles are the densest.Composition of the lipoproteinsLipoproteinSourceDiameter (nm)Density (g/mL)CompositionMain Lipid ComponentsApolipoproteinsProtein (%)LipidChylomicronsIntestine90-1000<0.951-298-99TriacylglycerolA-I, A-II, A-IV,l B-48, C-I, C-II, C-III, EChylomicron remnantsChylomicrons45-150< 1.0056-892-94Triacylglycerol, phospholipids,cholesterolB-48, EVLDLLiver (intestine)30-900.95-1.0067-1090-93TriacylglycerolB-100, C-I, C-II, C-IIIIDLVLDL25-351.006-1.0191189Triacylglycerol, cholesterolB-100, ELDLVLDL20-251.019-1.0632179CholesterolB-100HDLLiver, intestine,VLDL, chylomicrons20-251.019-1.0633268Phospholipids, cholesterolA-I, A-II, A-IV, C-I, C-II, C-III, D,2 EHDL1HDL210-201.063-1.1253367HDL35-101.125-1.2105743PreP-HDL3<5>1.210 A-IAlbumin/free fatty acidsAdipose tissue >1.28199-1Free fatty acids 1 Secreted with chylomicrons but transfers to HDL.Associated with HDL2 and HDL3 subtractions.3Part of a minor fraction known as very high density lipoproteins (VHDL).


Question: Gaucher&;s disease is due to deficiency of enzyme

Gaucher&;s disease is a lipid storage disease. It is due to the deficiency of beta-glucosidase. Results accumulation of glucocerebroside.Ref: DM Vasudevan, 7th edition, page no: 193


Question: Saturated fatty acids containing up to 16 carbon atoms are assembled in

Cytoplasm

The end product of cytosolic fatty acid synthesis cycles is saturated 16-carbon palmitic acid.
Elongation of pre-existing fatty acid :-
(i) Microsomnal (endoplasmic reticulum) :- Elongation of palmitic acid (16-C) into longer chain fatty acids
(ii) Mitochondrial :- Elongation of short and medium chain fatty acids containing fewer than 16 carbon atoms


Question: Site of absorption of Vitamin B12

Mnemonic Vitamin B12: 1 + 2 = 3
So maximum absorption in third part of small intestine. i.e: Ileum.


Question: The amino acid producing (a major source of) ammonia in the kidney is

Formation and secretion ammonia by renal tubular cells maintain acid-base balance. Ammonia is formed from glutamine by glutaminase.


Question: A 5 year old boy presents with hepatomegaly, hypoglycaemia & ketosis. The diagnosis is

Patients with type I GSD may present in the neonatal period with hypoglycemia and lactic acidosis.

These children often have doll-like faces with fat cheeks, relatively thin extremities, short stature and a protuberant abdomen that is due to massive epatomegaly; the kidneys are also enlarged, whereas the spleen  and heart are normal.
The biochemical hallmarks of the Type Ia GSD (von Gierke’s) disease are hypoglycemia, lactic acidosis, hyperuricemia and hyperlipidemia.


Question: Glucogenic amino acid is transpoed to the liver most commonly by


Question: Prostaglandins are

Unsaturated Fatty Acids Contain One or More Double Bonds
Unsaturated fatty acids may be further subdivided as follows:

Monounsaturated (monoethenoid, monoenoic) acids, containing one double bond.
Polyunsaturated  (polyethenoid,  polyenoic)  acids,  containing two or more double bonds.
Eicosanoids: These compounds, derived from eicosa (20-carbon) polyenoic fatty acids, comprise the prostanoids, leukotrienes (LTs), and lipoxins (LXs).

Prostanoids include prostaglandins (PGs), prostacyclins (PGIs), and thromboxanes (TXs).
HARPERS ILLUSTRATED BIOCHEMISTRY30th ed, Page No:213


Question: 1st product of tryptophan catabolism is

Tryptophan is an aromatic essential amino acid The major metabolic fate of tryptophan is to be oxidized by tryptophan pyrrolase (tryptophan di-oxygenase) It is a hemoprotein. The enzyme is inducible by coicosteroids. <img src=" /> in tryptophan catabolism the first product is 3-hydroxykynurenine ref Satyanarayana 4th ed page 145


Question: FIGLU is intermediate product of metabolism of

Ans. a (Histidine) (Ref. Harper's Biochemistry 28th/pg. 16).# Figlu or N-formimino glutamate - is formed during catabolism of Histidine.# During process, transfer of the formimino group of Figlu to tetrahydrofolate (H4 folate) forms glutamine. In folic acid deficiency, this reaction is partially or totally blocked and figlu is excreted in the urine.# Excretion of "Figlu" following a test dose of Histidine therefore provides a diagnostic test for folic acid deficiency.# Figlu test and Histidine test: Formimino-glutamate (figlu), a catabolite of Histidine, transfers its formimino group to H4- folate to form N5 formimino-H4 folate.In folate deficiency, Figlu will accumulate after oral challenges with Histidine.Histidine:# maximum buffering capacity- Maximum pH regulation seen# has no charge at neutral pH- proteinate and deproteinate at neutral pH# In folic acid deficiency, group transfer to THF is impaired and Figlu is excreted.


Question: Substrate level phosphorylation is seen in the conversion of

Substrate level phosphorylation

It is the production of ATP (or GTP) at substrate level without participation of electron transport chain.
It occurs in glycolysis and citric acid cycle, at following steps :-


Question: Number of structural gene in Lac operon

Lactose operone or Lac operon The lac operon is a region of DNA in the genome of E. coli that contains following genetic elements ? i) Three structural genes :- These code for 3 proteins that are involved in catabolism of lactose. These genes are 'Z' gene (codes for P-galactosidase), 'Y' gene (codes for galactoside permease), and 'A' gene (codes for thiogalactoside transacetylase). ii) Regulatory gene (lac i) It produces repressor protein. iii) A promotor site (P) :- It is the binding site for RNA polymerase. It contains two specific regions ? a) CAP site (Catabolite activator protein binding site). b) RNA polymerase binding site iv) An operator site (0) :- Repressor binds to this site and blocks transcription. 3 Structural genes are expressed only when '0' site is empty (repressor is not bound) and the CAP site is bound by a complex of cAMP and CAP (catabolite gene activator protein).


Question: Gout is a metabolic disorder of


Question: Tricarboxylic acid cycle does not occur in

RBCs - don't contain mitochondria-No TCA cycle Pathways that occur in mitochondria: * Fatty acid oxidation (b-oxidation) * TCA cycle * Oxidative phosphorylation and ETC * Ketone body synthesis and Utilization . Mitochondrial Protein and DNA synthesis


Question: Aspaame contains

Aspaame is made from aspaic acid and phenylalanine , both are aminoacds . It is 200 times sweeter than sugar. Aspaame is not suitable for people with phenlketonuria. REFERNCE : DM VASUDEVAN TEXTBOK EIGHTH EDITION ; Page no: 99


Question: Enzyme involved in binding of & for conjugated bilirubin formation is

In the liver, bilirubin is conjugated with glucuronic acid by the enzyme glucuronyltransferase, making it soluble in water: the conjugated version is the main form of bilirubin present in the "direct" bilirubin fraction. Much of it goes into the bile and thus out into the small intestine. Ref biochemistry satyanarayana 4e


Question: Genetic deficiencies of NADPH oxidase cause


Question: Mucopolysaccharide hyaluronic acid is present in

Ans. is 'a' i.e. Vitreous humar Distribution of various glycosaminoglycansHyaluronic acidSynovial fluid, vitreous humor, loose connective tissueChondroitin sulfatesCartilage, bone, corneaKeratan Sulfate ICorneaKeratan Sulfate IILoose connective tissueHeparinMast cellsHeparan SulfateSkin fibroblasts, aortic wallDermatan SulfateWide distribution

Chemistry of Carbohydrates, Amino sugars, and Mucopolysaccharides


Question: Pseudouridine found in

Pseudouridine (abbreted by the Greek letter psi- Ps) is an isomer of the nucleoside uridine in which the uracil is attached a carbon-carbon instead of a nitrogen-carbon glycosidic bond. It is the most prevalent of the over one hundred different modified nucleosides found in RNA. Ps is found in all species and in many classes of RNA. Ref-Harpers illustrated biochemistry 30/e p649


Question: Stain not used for lipid

Congo red Congo red is not used in lipid staining. It is used in the staining of antyloid protein STAINING FOR LIPIDS Non polar lipids Examples Stain used * Unconjugated lipids Fatty acids Oil red 0, Sudan black, Sudan III & IV Cholesterol Filipin * Esters Cholesteryl esters Schultz Monodi and Tri-glycerides Calcium lipase * Polar lipids - Phospholipids - Glycerol bases Phosphatidylcholine Nile blue sulfate Phosphatidylserine Nile blue sulfate Phosphatidylethanol amine Plasmal reaction - Sphingosine-base Sphingomyelins Ferric hematoxylin - Glycolipids Cerebrosides PAS Sulfatides Acetone/Toluidine blue Gangliosides PAS


Question: Non essential amino acids

The remaining 10 amino acids are non-essential, because their carbon skeleton can be synthesized by the body.
Reference: Vasudevan 7th  ed, pg 27

May be synthesized in the body from essential amino acids

May be synthesized in the body in diseased states .


Question: Introduction of DNA with the help of electricity is


Question: Nothern blot is used for the separation of

Used to demonstrate specific RNA The total RNA is isolated from the cell, electrophoresed and then blotted on to a membrane This is. then probed with radioactive cDNAThere is RNA -DNA hybridization Used to detect gene expression in tissuesRef: DM Vasudevan, 7th edition, page no: 634


Question: Transamination reaction requires

The enzyme catalyzing transamination reaction as a group are known as aminotransferases. These enzymes have pyridoxal phosphate as prosthetic group,Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 201, fig 15.8


Question: Chian initiation in protein synthesis is by

INITIATOR CODON : AUG is the initiator codon. It also acts as the codon for methionine. In a few proteins, GUG acts as initiator codon. REF :DM VASUDEVAN TEXTBOOK ; 8th EDITION ;Page no :586.


Question: GAG affected in Sanfilippo syndromes is

Disease name Abbretion Enzyme Defective GaG(s) affected Symptoms Sanfilippo syndrome A MPS IIIA Heparan sulfate-N-sulfatase Heparan sulfate Delay in development, motor dysfunction Sanfilippo syndrome B MPS IIIB a-N-Acetylglucosaminidase Heparan sulfate As MPS IIIA Sanfilippo syndrome C MPS IIIC a-Glucosaminide N-acetyltransferase Heparan sulfate As MPS IIIA Sanfilippo syndrome D MPS IIID N-Acetylglucosamine 6-sulfatase Heparan sulfate As MPS IIIA Reference: Harper; 30th edition; Page no:639; Table: 50-8


Question: The reducing equivalent for fatty acid synthesis is derived from


Question: Uric acid is formed in humans in

Uric acid is a chemical created when the body breaks down substances called purines. Purines are found in some foods and drinks. These include liver, anchovies, mackerel, dried beans and peas, and beer. Most uric acid dissolves in blood and travels to the kidneys. Ref-Sathyanarayana 4/e


Question: During gluconeogensis reducing equivalents from mitochondria to cytosol are transpoed by

A i.e. MalateMallate shuttle is a system by which reducing equivalents (NADH) produced in glycolysisQ are transferred from cytosol to mitochondria to yield energy.NADH produced in the glycolysisQ, is extramitochondrial where as the electron transpo chain, where NADH has to be oxidized to NAD+ is in the mitochondria (Oxidation of 1 NADH yields 3 ATP/2.5 ATP). NADH is impermeable to mitochondrial membrane, so to enable transfer of NADH inside mitochondria Shuttle system is utilized.


Question: Fatty acids can not be utilised by

RBC can utilise only glucose even during fasting / starvation.


Question: Vitamin A is stored mainly as retinol esters in

retinal is reduced to retinol by retinal reductase in the intestinal mucosa intestine is the major site of absorption vitamin is transpoed and stored in the liver as retinol palmitate ref DM Vasudevan 8th ed page 454


Question: Peptidyl transferase is a/an

The Peptidyl transferase is an aminoacyltransferase (EC 2.3.2.12) 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.


Question: The rich source of vitamin E is

Many vegetable oils  are rich  sources of vitamin E. Wheat germ oil,  cotton seed oil, peanut oil, corn oil and sunflower oil are the good sources of this vitamin.
Ref : Satyanarayana, 3rd ed, pg. 129


Question: The amino acid required for the synthesis of haem is


Question: After overnight fasting, levels of Glucose transpoers are reduced in

C i.e. AdipocytesInsulin sensitive (dependent) glucose transpoer, GLUT- 4 that are found in adipose tissueQ and skeletal muscles are reduced in fasting state, when the insulin levels are low.


Question: Fluoroacetate blocks the Krebs cycle by inhibiting the following enzyme

The poison fluoroacetate is found in some of the plants, and their consumption can be fatal to grazing animals. Some fluorinated compounds used as anticancer agents and industrial chemicals (including pesticides) are metabolized to fluoroacetate. It is toxic because fluoroacetyl-CoA condenses with oxaloacetate to form fluorocitrate, which inhibits aconitase, causing citrate to accumulate.Reference: Harper&;s Biochemistry; 30th edition; Chapter 16; The Citric Acid Cycle: The Central Pathway of Carbohydrate, Lipid & Amino Acid Metabolism


Question: Formation of Okazaki fragments occur in

In molecular biology, DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule. This process occurs in all living organisms and is the basis for biological inheritance. DNA is made up of a double helix of two complementary strands. During replication, these strands are separated. Each strand of the original DNA molecule then serves as a template for the production of its counterpa, a process referred to as semiconservative replication. Cellular proofreading and error-checking mechanisms ensure near perfect fidelity for DNA replication


Question: Essential amino acid is

A semi-essential amino acid that occurs in proteins and is involved in the urea cycle and in the synthesis of creatine. Preparations of the base or the glutamate or hydrochloride salt are used in the treatment of <a href=" and in the assessment of pituitary function.
Ref: Harper&;s Illustrated Biochemistry, 26th edition, page no: 237


Question: Role of molecular oxygen in ETC is

As it turns out, the reason you need oxygen is so your cells can use this molecule during oxidative phosphorylation, the final stage of cellular respiration. ... Oxygen sits at the end of the electron transpo chain, where it accepts electrons and picks up protons to form water

Transfer of reducing equivalent from cytosol to mitochondria


Question: Transpo of fatty acids through mitochondrial membrane is by

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, (CH3)3-N+-CH2-CHOH-CH2-COOH. It is synthesized from lysine and methionine in liver and kidney.Ref: MN Chatterjea Textbook of Medical Biochemistry, 6th edition, page no: 130


Question: ATPs generated in TCA cycle

ATP Generating Steps in TCA Cycle There are 3 NADH molecules generated during one cycle, each of them will give rise to 2 1/2 ATPs on oxidation by electron transpo chain (ETC); so altogether they will give 3 x 2 1/2 = 7 1/2 (7.5) high energy phosphates. The FADH2 will generate 1 1/2 molecules of ATP. In addition, one molecule of GTP (equivalent to one molecule of ATP) is formed by substrate-level phosphorylation. Hence, per turn of the cycle, 10 high energy phosphates are produced. These steps are marked in Figure 18.5 and in Table 18.1. The summary is shown in Box 18.2. Note: Recent work shows that in the electron transpo chain, NADH produces only 2.5 ATPs and FADH only 1.5 ATPs. The old values (used in the Table 18.1. ATP generation steps Step Reactions no. CoATPs ATPs enzyme (old(new calculation) 3Isocitrate - -- Alpha-ketoglutarate dehydrogenase reaction is the only one irreversible step in the cycle. The free energy changes of the reactions of the cycle are such that the cycle will operate spontaneously in the clockwise direction. Only about 33% of energy liberated is trapped as ATP. The rest is used to keep the body temperature at a higher level than the environment.Ref: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 220


Question: Menke disease is associated with

Menke's Disease: (X linked , a condition of Cu deficiency) Deficient production of Cu binding P- type ATPase in intestine Menke's disease is due to defective lysyl oxidase C/F: Mental retardation, Grey kinky hair. OTHER MINERAL DEFICIENCIES =Selenium - -Selenium as selenocysteine is an essential component of the enzyme glutathione peroxidase Deficiency - Keshan's disease - endemic cardiomyopathy(china) muscles weakness, hypothyroidism, HTN, eczema. selenium deficiency lead to increased risk of cardiovascular disease and cancer Toxicity - selenium toxicity lead to Selenosis. selenosis clinical features are emotional disturbance, diarrhea, hair loss, garlic odor (due to dimethyl selenide) in breath Selenium is also an intracellular antioxidant which complements the role of Vitamin E. Dietary sources of selenium include seafood, muscle meat, and some cereals. =Zinc Deficiency - Acrodermatitis enteropathica It is an autosomal recessive disease due to a defect in zinc absorbing transmembrane protein. Symptoms: Growth retardation Diarrhea Alopecia Dermatitis around the orifices Gonadal atrophy Impaired wound healing Zinc acts as a cofactor for: Carbonic anhydrase Carboxypeptidase Lactate dehydrogenase Alcohol dehydrogenase Alkaline phosphatase =Iron Deficiency - microcytic hypochromic anemia


Question: The first lipoprotein to increase in concentration in the blood after ingestion of 400 g of jellybeans (carbohydrate) is

VLDL is synthesized in the liver, particularly after a high carbohydrate meal. It is formed from triacylglycerols that are packaged with cholesterol, apolipoproteins (particularly, apoB-100), and phospholipids, and it is released into the blood, where it acquires apoC-II and apo E.VLDL is synthesized by the liver from dietary sugar (present in jelly-beans). LDL is the cholesterol-rich particle in the blood. Cells take up LDL by LDL binding to the LDL receptor, and the LDL-LDL receptor complex enters the cell via endocytosis. Once inside the cell, the cholesterol is released from cholesterol esters by a lysosomal enzyme and enters the cytoplasm of the cell for further processing. Chylomicrons are produced from dietary lipids and cholesterol in the intestinal epithelial cells. HDL is involved in reverse cholesterol transport, which requires the LCAT reaction. Fatty acids, because they are so hydrophobic, cannot travel freely in the blood and need to be bound to albumin for transport through the circulatory system.


Question: CAP in Lac operon is an example of

Catabolite activator protein(CAP) must bind to cAMP to activate transcription of the lac operon by RNA polymerase. CAP is a transcriptional activator with a ligand-binding domain at the N-terminus and a DNA-binding domain at the C-terminus.


Question: 21st Amino acid is

Selenocysteine, the 21st Amino AcidSelenocysteine is present at the active site of several human enzymes that catalyze redox reactions. Examples include thioredoxin reductase, glutathione peroxidase, and the deiodinase that conves thyroxine to triiodothyronine.Ref: Harper&;s Biochemistry; 30th edition; Chapter 27 Biosynthesis of the Nutritionally Nonessential Amino Acids


Question: Hepatomegaly is an essential feature of

Hepatomegaly is an essential feature of von Gierke's disease (all glycogen storage diseases except type 2, 5, 7), Hurler (Scheic) syndrome (& all mucopolysaccharidosis) and Nieman-Pick disease. But the hepatic involvement of hepatic porphyria is variable. Patients with chronic hepatic porphyria (porphyria cutanea tarda), however may show liver enlargement d/t fatty infiltration but frank sings of hepatomegaly and iron overload are rare.


Question: In PCR

The enzyme is not denatured at high temperature The polymerase reaction allowed to take place at 72 *c for 30 seconds in presence of dNTP

211 copies formed after 'n' members of multiple


Question: Pompe’s disease is caused due to deficiency of


Question: Sakaguchi’s reaction is specific for

Sakaguchi’s Test for Arginine : Free arginine or arginyl residues in proteins react with alpha-naphthol and alkaline hypobromite to give bright-red color. This is due to the guanidium group.
Reference: Vasudevan 7th  ed, pg 32


Question: The enzymes engaged in the transfer of electrons are known as

Enzymes are grouped into the following six classes: 1.Oxidoreductases: Enzymes that catalyze oxidations and reductions. 2.Transferases: Enzymes that catalyze the transfer of moieties such as glycosyl, methyl, or phosphoryl groups. 3.Hydrolases: Enzymes that catalyze hydrolytic cleavage of C'C, C'O, C'N, and other covalent bonds. 4.Lyases: Enzymes that catalyze the cleavage of C'C, C'O, C'N, and other covalent bonds by atom elimination, generating double bonds.5.Isomerases: Enzymes that catalyze geometric or structural changes within a molecule. 6.Ligases: Enzymes that catalyze the joining together (ligation)Oxidoreductases are fuher classified into four groups: oxidases, dehydrogenases, hydroperoxidases, and oxygenasesReference: Explanation: Harper's Biochemistry; 30th edition; Chapter 7; Enzymes: Mechanism of action


Question: Calorific value of fat is


Question: In translation process, proof reading of mRNA done by


Question: A patient with abetalipoproteinemia frequently manifests with delated blood clotting. This is due to inability to

Type-III: Familial Dys-Beta Lipoproteinaemia:Synonyms: Broad Beta disease, 'Remnant' removal diseaseThe disease is characterised by:Increase in b-lipoproteins (LDL |)Increase in Pre-b-lipoproteins (VLDL |);Actually rise is in IDL (VLDL remnant). This appears as broad b-band ("floating" b-band)-b- VLDL on electrophoresis. Also, there is hypercholesterolemia and hyperiglyceridemia.Inheritance: Autosomal dominant.Metabolic defects:Increased concentration of apo-E |.Increased synthesis of apo-B |.Conversion of normal VLDL to b-VLDL (IDL) and its degradation without conversion to LDL. Defect is in "Remnant" metabolism.Clinical feature: Presents with Xanthomastuberous and palmar Xanthomas. Premature cardiovascular diseases and atherosclerosis common. Also prone to develop peripheral vascular diseases.Treatment:By weight reductionLow carbohydrate diets, containing unsaturated fats and little cholesterolRef: Textbook of Medical Biochemistry, 8th Edition, Dr (Brig) MN Chatterjea, Rana Shinde, page no: 452,453


Question: Hyperlipidemias are treated by administering the following vitamin in megadoses

High doses of niacin are effective in lowering serum triglyceride, low-density lipoprotein, and lipoprotein-a levels and in elevating high-density lipoprotein levels. In high doses, Niacin causes dilatation of blood vessels and flushing, along with skin irritation. Intakes of both nicotinic acid and nicotinamide in excess of 500 mg/d also cause liver damage.Harper 30th edition Pg: 557


Question: Receptors on blood cells accept cholesterol from

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. Metabolism of LDL and LDL Receptors LDL is taken up by peripheral tissues by receptor-mediated endocytosis. LDL receptors are present on all cells but most abundant in hepatic cells. LDL receptors are located in specialised regions called clathrin-coated pitsBinding of LDL to the receptor is by apo-B-100 and uptake of cholesterol from LDL is a highly regulated process. When the apo-B-100 binds to the apo-B-100 receptor, the receptor-LDL complex is internalised by endocytosis. The endosome vesicle thus formed fuses with lysosomes. The receptor is recycled and returns to the cell surface. The LDL paicle, along with apoproteins and cholesterol ester are hydrolysed by lysosomal hydrolases, forming amino acids and free cholesterol. The free receptors can now return to the membrane surface to bind fuher LDL molecules . Approximately 70% of LDL is degraded in the liver, and the rest in extra-hepatic tissues. For their work on LDL receptors, Michael Brown and Joseph Goldstein were awarded Nobel prize in 1985. Function of LDL About 75% of the plasma cholesterol is incorporated into the LDL paicles. LDL transpos cholesterol from liver to the peripheral tissues. The cholesterol thus liberated in the cell has three major fates: i. It is used for the synthesis of other steroids like steroid hormones. ii. Cholesterol may be incorporated into the membranes. iii. Cholesterol may be esterified to a MUFA by acyl cholesterol acyltransferase (ACAT) for storage. The cellular content of cholesterol regulates fuher endogenous synthesis of cholesterol by regulating HMG CoA reductase.LDL and Clinical Applications LDL concentration in blood has positive correlation with incidence of cardiovascular diseases. A fraction of cholesterol is taken up by macrophages, this is not a regulated pathway. Increased levels of LDL or modification of LDL by glycation (as seen in diabetes mellitus) or oxidation increases the fraction of cholesterol taken up by macrophages. LDL infiltrates through aerial walls, and is taken up by macrophages or scavenger cells. This is the staing event of atherosclerosis leading to myocardial infarction . When these cells become engorged with cholesterol, foam cells are formed, that get deposited in the subendothelial space triggering formation of atheromatous plaque . Procoagulant changes are induced in the endothelium resulting in increased chances of thrombosis and coronary aery disease. Since LDL-cholesterol is thus deposited in tissues, the LDL (low-density lipoprotein) variety is called "bad cholesterol" and LDL as "Lethally Dangerous Lipoprotein" in common parlanceRef: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 153 - 154


Question: Soing of protein molecules is performed in

Main function of golgi apparatus is protein soing, packaging, and secretion. Mitochondria are the powerhouse of the cell.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 12


Question: Glutathione peroxidase contains

Glutathione peroxidase is an impoant enzyme in cellular antioxidant defense systems, detoxifying peroxides, and hydroperoxides. As a component of the glutathione cycle, it protects the liver from reactive oxygen metabolites. Selenocysteine is present at the catalytic site of glutathione peroxidase, and selenium availability regulates glutathione peroxidase enzyme activity.


Question: Measurement of bilirubin in serum is by

Measurement of Bilirubin in SerumQuantitation of bilirubin employs a colorimetric method based on the reddish-purple color formed when bilirubin reacts with diazotized sulfanilic acid. An assay conducted in the absence of added methanol measures "direct bilirubin," which is bilirubin glucuronide. An assay conducted in the presence of added methanol measures total bilirubin. The difference between total bilirubin and direct bilirubin is known as "indirect bilirubin," and is unconjugated bilirubin.Ref: Harper&;s Biochemistry; 30th edition; Chapter 31; Porphyrins & Bile Pigments


Question: Lysosomal accumulation of sphingomyeline is seen in


Question: Daily vitamin A intake


Question: Menadione is an analogue of

ref: Ganong&;s review of medical physiology; 24th edition; page no;492 menadione C11H8O2(2-methyl-1,4-naphthoquinone) A compound used as a vitamin K supplement; impoant in blood clotting.


Question: Detoxification of drugs is controlled by

Cytochrome p450enzymes are heme-containing enzymes localized in the endoplasmic reticulum of the liver. they engage in biotransformation reactions.they are monoamine oxidase. RH+O2+NADPH+H+________________> ROH+H2O+NADP+ Cytochrome p 450contains phosphatidylcholine. Almost all common drugs are metabolized by p450 system.there are about 150 isoforms.eg: CYP1A1 THEY are inducible enzymes .phenobarbitones causes increased activity of warfarin which is metabolized by CYP2C9. Some of the isoforms exhibit low catalytic reactivity. This explains variation in drug responses in different persons.Ref: MN Chatterjea Textbook of Medical Biochemistry, 7th Edition, Page no: 545


Question: Enzymes not impoant in testosterone biosynthesis

Progesterone is conveed to 18hydroxyprogestrone by 18 -hydroxylaseThese reactions are effected by hydroxylationThese specific hydroxylases are mono-oxygenasesRef: DM Vasudevan, 7th edition, page no: 665


Question: Enzyme activity measured in beri beri is


Question: tRNA met would recognize

initiation of protein synthesis can be studied as 4 steps Recognition stepSFormation of pre-initiation complex i.e.binding of ternary complex of met-tRNA Binging of mRNA to the pre-initiation complex to form 43s initiation complexThe 43s initiation complex is combined with the 60s ribosomal subunit to form 80s initiation complexRef: DM Vasudevan, 7th edition, page no: 600


Question: Albinism is due to deficiency of

Tyrosinase is completely absent, leading to defective synthesis of melaninRef: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 238, fig 18.7


Question: Mannose 6 phosphate containing freshly synthesized proteins are directed to


Question: The structural protein are involved in maintaining the shape of a cell or in the formation of matrices in the body. The shape of these proteins is

Proteins responsible for maintaining the structural strength of cells (i.e. cytoskeleton) and tissues include collagens, keratin and myosin etc. These proteins are classified as fibrous proteins.


Question: Large amount of SER is found in cells storing

Cholesterol(lipid) is synthesized in the smooth endoplasmic reticulum from acetyl CoA. The rate-limiting step is the formation of mevalonate from 3-hydroxy 3-methylglutaryl-CoA by HMG CoA reductase and lanosterol is the first cyclic intermediate.SER synthesise lipids whereas RER synthesise proteinsRef: Harper biochemistry: 267


Question: Decreased glycolytic activity impairs oxygen transport by hemoglobin due to

Decreased production of 2,3-bisphosphoglycerate

2, 3 DPG is produced by an alternative pathway in glycolysis.
If the glycolytic activity is decreased, the levels of 2,3 - DPG in RBCs will decrease.
Decreased level of 2,3 - DPG causes:-

Shifts the oxygen-hemoglobin curve to the left
Increases the oxygen affinity of hemoglobin.

Decreased production of 2,3 - bisphosphoglycerate


Question: Lack of a specific lysosomal hydrolase for glycoproteins will most likely cause

Lack of a specific lysosomal hydrolase for glycoproteins cause a group of very rare.autosomal recessive genetic disease called glycoprotein storage diseases(oligosaccharidoses). Lysosomal acid hydrolases are specific for the removal of the component of the glycoprotein. They are primarily exoenzyme that remove their respective groups in sequence in the reverse order of their incorporation Reference: Lippincotts illustrated biochemistry 6th Edition pg 320


Question: SYBR Green Dye is used for

Dyes such as SYBR Green I, that intercalate into double-stranded DNA (or for other dyes, bind to the DNA minor groove) are more convenient to have on hand and less expensive than probes.The disadvantages of dyes include detection of non-specific double-stranded reaction products (resulting in increased background or false positives). In addition, some dyes are known to inhibit the PCR reaction.


Question: Ideal biologic solvent is

WATER IS AN IDEAL BIOLOGIC SOLVENTA water molecule is an irregular, slightly skewed tetrahedron with oxygen at its center.Ref: Harper&;s Biochemistry; 30th edition; Chapter 2; Water & pH


Question: Enzyme regulated by phosphorylation

Glycogen Synthase catalyzes elongation of glycogen chains. Glycogen Synthase catalyzes transfer of the glucose moiety of UDP-glucose to the hydroxyl at C4 of the terminal residue of a glycogen chain to form a (1 4) glycosidic linkage (diagrams p. 633):glycogen (n residues) + UDP-glucose glycogen (n +1 residues) + UDPRef: DM Vasudevan, 6th edition, page no: 106


Question: Cancer cells derive its nutrition from

Tissues depending mainly on glucose ( Glycolysis) as metabolic fuel-White fibres of skeletal muscle, mature erythrocytes, brain, GIT, renal medulla, skin, many cancer cells.


Question: Xeroderma pigmentatosa is caused due to a group of closely related abnormalities in


Question: Trypsin cleaves

Activation of zymogens: Enteropeptidase (formerly called enterokinase), an enzyme synthesized by and present on the luminal surface of intestinal mucosal cells of the brush border membrane, conves the pancreatic zymogen trypsinogen to trypsin by removal of a hexapeptide from the N-terminus of trypsinogen. Trypsin subsequently conves other trypsinogen molecules to trypsin by cleaving a limited number of specific peptide bonds in the zymogen. Enteropeptidase, thus, unleashesa cascade of proteolytic activity because trypsin is the common activator of all thepancreatic zymogens .


Question: Colour vision is tested with help of the

(C) Ishihara plates # ISHIHARA COLOR TEST is an example of a color perception test for red-green color deficiencies.> It was named after its designer, Dr. Shinobu Ishihara, a professor at the University of Tokyo.> The test consists of a number of colored plates, called Ishihara plates, each of which contains a circle of dots appearing randomized in color and size.> Within the pattern are dots which form a number or shape clearly visible to those with normal color vision, and invisible, or difficult to see, to those with a red-green color vision defect.


Question: Keratin of skin and nail differ because of

Ans. is 'a' i.e Disulphide bond " the keratins are a family of closely related fibrous proteins, whose structure is nearly entirely alpha- helical. They are a major component of tissues such as hairs and skin; their rigidity is determined by the number of disulphide bonds between the constituent polypeptide chains " -Lippincott's BiochemThus the difference in rigidity between the keratins of hairs and nail in because of the number of disulphide bonds.Keratins are rich in cysteine*( a sulphur containing amino acid ) which provides covalent disulphide cross-link between adjacent polypeptide chains.

Miscellaneous (Structure & Function of Proteins)


Question: Complex I of ETC is inhibited by

Inhibitors of ETC Site-I (Complex-I) Rotenone: A fish poison and also insecticide. Inhibits transfer of electrons through complex-I-NADH-Q-reductase.Amobarbital (Amytal) and Secobarbital: Inhibits electron transfer through NADH-Q reductase.Piericidin A: An antibiotic. Blocks electron transfer by competing with CoQ.Drugs: Chlorpromazine and hypotensive drug like guanethidine.Ref: MN Chatterjea Textbook of Medical Biochemistry, 6th edition, page no: 143


Question: Ferric chloride test in PKU gives

Urine of the patient contains phenylketones about 500- 3000 mg/day . This could be detected by adding a drop of ferric chloride to the urine . A transient blue - green color is a positive test. But this is a less reliable test. Ref : DM.VASUDEVAN.TEXTBOOK ; SEVENTH EDITION ; PAGE NO : 237.


Question: The amino acid that produces kinks in the b pleated structure of proteins is

Proline and 4hydroxy proline confer strength to fibrous proteins like collagen,elastin,keratin etc. in their beta pleated structureRef: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 244


Question: Inhibition of glycolysis by increased supply of O2 is

uCrab Tree Effect - Increasing concentrations of glucose accelerates glycolysis (the breakdown of glucose) which results in the production of appreciable amounts of ATP through substrate level phosphorylation. uPasteur effect - Under aerobic conditions, glycolysis is inhibited. This inhibitory effect of oxygen on glycolysis.uWarburg Effect - Most cancer cells predominantly produce energy by a high rate of glycolysis followed by lactic acid fermentation in the cytosol, rather than by a comparatively low rate of glycolysis followed by oxidation of pyruvate in mitochondria as in most normal cells.Lehninger, Albe (2008). Principles of Biochemistry. 4th ed, p. 533.


Question: type 2 hypercholesterolemia occubrs due to

Type II A(Primary familial hypercholesterolemia)There is elevation of LDL. Patients seldom survivethe second decade of life due to ischemic headisease (Table 25.4). The cause is the LDL receptordefect. Receptor deficiency in liver and peripheraltissues will result in the elevation of LDL levels inplasma, leading to hypercholesterolemia. The LDLreceptor defect may be due to the following reasons:1. LDL receptor deficiency.2. Defective binding of B-100 to the receptor. Asubstitution of glutamine for arginine at 3500thamino acid results in poor binding to LDLreceptors. This defect is known as B-3500 orfamilial defective apo-B.3. The receptor-ldl complex is not internalized.Secondary type II hyperlipoproteinemia is seenin hypothyroidism, diabetes mellitus, nephroticsyndrome and cholestasisRef: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 300


Question: Maximum content of triglycerides are found in

Ans. is 'c' i.e. Chylomicrons Maximum content of TG's is seen in - Chylomicrons*Maximum content of exogenous TG's is seen in -Chylomicrons*Maximum content of endogenous TG's is seen in -VLDL*Maximum cholesterol is seen in - LDL*


Question: Most commonly occurring amino acid in the collagen structure is

About 33%of aminoacids of collagen is glycine.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 720


Question: A mutation that results in premature termination of incorporation of amino acid into a peptide chain is a

In genetics, a nonsense mutation is a point mutation in a sequence of DNA that results in a premature stop codon or a nonsense codon in the transcribed mRNA, and in a truncated, incomplete, and usually nonfunctional protein product. It differs from a missense mutation, which is a point mutation where a single nucleotide is changed to cause substitution of a different amino acid. Some genetic disorders, such as thalassemia and DMD, result from nonsense mutations.


Question: Cytochrome oxidase is inhibited by

Site I: This involves the transfer of electrons from NADH-CoQ. Obviously, this step is omitted by succinic dehydrogenase whose FADH2 prosthetic group transfers its electrons directly to CoQ bypassing NADH. This step is blocked by piericidin, rotenone, amobarbital, ceain drugs like chlorpromazine, guanethidine. among barbital is a barbiturate derivativeRef: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 143


Question: Type of collagen in brain

Type XXV is present in the brain Reference: Harper; 30th edition; Page no: 628 Table no: 50-1


Question: Biotin is needed in

Biotin acts as co- enzymes for carboxylation reactions .Bioitin captures a molecule of CO2 which is attached to nitrogen of biotin molecule.Energy required for this reaction is provided by ATP.Tgen activated carboxyl group is transferred to the substrate.Biotin requiring CO2 Fixation reactions. Acetyl CoA + CO2 + ATP=Methyl malonyl CoA + ADP+ Pi This is the rate limiting reaction in fattyacid synthesis. Propionyl CoA + CO2 + ATP = Methyl malonyl CoA + ADP + Pi In oxidation of odd chain fatty acids. Pyruvate+ CO2 + ATP = Oxaloacetate + ADP + Pi Oxaloacetate acts as catalyst for TCA cycle and as enzyme in gluconeogenic pathway Reference: DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION page no 485 Co-enzyme Main reaction using the co -enzyme Group transferred Thiamine pyrophosphate(TPP) oxidativedecarcoxylation of alpha keto acids in BPG shunt Hydroxyethyl Pyridoxalphosphate(PLP) Transamination, decarcoxylation of amino acids Aminogroup Biotin fatty acid synthesis, TCA cycle carbondioxide Co- enzyme-A ( Co-A) TCAcycle, fatty acid synthesis,gluconeogenisis, activation of acetoacetate, detoxification Acylgroup Tetrahydrofolate (FH4) Transmethylation reactions where methyl group required for synthesis of choline , epinephrine , creatine. One carbon groups Adenosinetriphosphate(ATP) universal energy currwncy Phosphate


Question: Alkaptonuria is due to deficiency of

(D) Homogentisic acid oxidase # Enzyme defect in Ochronosis (Alkaptonuria):> Defective enzyme in alkaptonuria is Homogentisate oxidase in tyrosine metabolism.> Homogentisate accumulates in tissues and blood, and is excreted into urine.> Homogentisate, on standing, gets oxidized to the corresponding quinones, which polymerize to give black or brown colour.> For this reason, the urine of alkaptonuric patients resembles coA are in colour.> Homogentiste gets oxidised by polyphenol oxidase to benzoquinone acetate which undergoes polymerization to form a pigment "Alkapton".> Alkapton gets deposited in connective tissues, bones and various organs resulting in a condition called "Ochronosis".> Many patients suffer from arthritis: and this is believed to be due to the deposition of pigment alkapton in the connective tissues.


Question: Composed mainly of triacylglycerols synthesized in intestinal epithelial cells is

VLDL is synthesized in the liver, particularly after a high carbohydrate meal. It is formed from triacylglycerols that are packaged with cholesterol, apolipoproteins (particularly, apoB-100), and phospholipids, and it is released into the blood, where it acquires apoC-II and apo E.Chylomicrons contain triacylglycerols synthesized from dietary lipid in intestinal epithelial cells. LDL is the cholesterol-rich particle in the blood. Cells take up LDL by LDL binding to the LDL receptor, and the LDL-LDL receptor complex enters the cell via endocytosis. Once inside the cell, the cholesterol is released from cholesterol esters by a lysosomal enzyme and enters the cytoplasm of the cell for further processing. VLDL contains newly synthesized triglyceride and cholesterol produced by the liver. HDL is involved in reverse cholesterol transport, which requires the LCAT reaction. Fatty acids, because they are so hydrophobic, cannot travel freely in the blood and need to be bound to albumin for transport through the circulatory system.


Question: The main source of energy derived from

Liver glycogen is the first main provider of energy during short term fasting.
Liver glycogen serves to maintain blood glucose between the meals. Therefore, liver glycogen is the most important reservoir as it comes to play its role in routine condition (between meals). Whereas, adipose tissue fuel is involved only on prolonged fasting and starvation.


Question: The enzyme not present in the skeletal muscles


Question: Transamination of Aspaate forms

Aspaate on transamination gives rise to Oxaloacetate which initiates the TCA cycle. Aspaate aminotransferase catalyzes the reaction.Ref: Textbook of Biochemistry; DM Vasudevan; 7th edition; Page no: 226


Question: Epimer combination (s) is/are

When sugars are different from one another, only in configuration with regard to a single carbon atom, other than reference carbon atom, they are called epimers\Ref: DM Vasudevan, 7th edition, page no: 71


Question: The following is an example for unusual base

It is present in tRNAPresent in the DHU OR D arm of tRNAServe as the recognition site for the enzyme which adds the amino acidRef: DM Vasudevan, 7th edition, page no: 597


Question: Stimulates the synthesis of milk proteins.

PRL is the only hormone listed that stimulates the synthesis of milk proteins. PRL will induce a-lactalbumin, which will stimulate lactose production.


Question: Most essential fatty acid is

(A) (Linoleic acid) (31- Satyanarayan(203- Harper 27th)EFA - should be supplied in the diet* Deficiency results in phrynoderma or toad skin* Cyclic fatty acids - normely chaumoogric acid is employed in the treatment of leprosy.* Most important EFA is Linoleic acid (because it server as a basis for the production of other essential fatty acids)* Essential fatty acids are- linoleic acid. Linolenic acids, arachidonic acid. Elcosapentanoic acid* Ecosanoids are formed from - C2o polyunsatured fatty acids (Arachidonic acid)*** Maximum source of linoleic is- sunflower oils*** Vegetables oils ** are rich source of poly unsaturated fatty acids.* Docosahexaenoic acid (DHA) is particularly needed for development of the brain and retina and is supplied via the placenta and milk *** The endoperoxide metabolites of arachidonic acid implicated in the pathogenesis of allergic bronchial asthma are Leukotriens ***TRANS FATTY ACIDS* TFA are chemically classified as unsaturated fatty acids but I have more like saturated fatty acids in the body that is they elevated serum LDL and they increase the risk of CHD* TFA do not occur naturally in plants, but occurs in small amounts in animals. However TFA are formed during the hydrogenation of liquid vegetable oils* TFA are a major component of many commercial baked gcods, such as cook ies and cakes and most deep - fried foods.* A clue to the presence of TFA in a food is the words " partially hydrogenated" on the list of package ingredients (363-64-Lippincorf s - Biochemistry)ALSO - REMEMBERRichest source of vit A - Fish liver oilRichest source of VIT D - cod liver oilRichest source of vit K - cow's milkRichest source of vit B12- LiverRichest source of folic acid - green leafy vegetablesRichest source of iron is - jaggeryRichest source iodine is - sea foods and cod liver oil* Fatty acids are stored as Triglycerides mainly in adipose tissue.


Question: Amphiphatic helices are

Many α helices have predominantly hydrophobic R-groups projecting from one side of the axis of the helix and predominantly hydrophilic R-groups projecting from the other side. These amphipathic helices are well adapted to the formation of interfaces between polar and nonpolar regions such as the hydrophobic interior of a protein and its aqueous environment. Clusters of amphipathic helices can create channels, or pores, through hydrophobic cell membranes that permit specific polar molecules to pass.
Note: Clusters of twisted strands of β sheet are called β barrels.
Ref: Harper’s illustrated biochemistry. 30th edition page no: 37

α helices having predominantly hydrophobic R-groups projecting from one side and predominantly hydrophilic R-groups projecting from the other side of the axis of the helix

Short segments of amino acids that join two units of the secondary structure


Question: Most abundant protein in humans is


Question: Impaired Glucose intolerance is caused by deficiency of

Ans. (a) ChromiumRef: Harrisons, 19th ed. pg. 96e-9* A deficiency of chromium can cause impaired glucose tolerance.* Physiologically, chromium potentiates the action of insulin in patients with impaired glucose tolerance, presumably by increasing insulin receptor-mediated signaling.* Rich food sources of chromium include yeast, meat, and grain products.* Note:# Deficiency of Selenium: Can cause cardiomyopathy (Keshan disease)# Selenium toxicity: Can cause selenosis (Kashinbeck disease)


Question: Gel filtration chromatography separates proteins based on

Gel filtration chromatography separates proteins based on their Stokes radius, the radius of the sphere they occupy as they tumble in solution. The Stokes radius is a function of molecular mass and shape. When rapidly tumbling, an elongated protein occupies a larger effective volume than a spherical protein of the same mass. Size-exclusion chromatography employs porous beads. The pores are analogous to indentations in a riverbank. As objects move downstream, those that enter an indentation are retarded until they drift back into the main current. Similarly, proteins with Stokes radii too large to enter the pores (excluded proteins), remain in the flowing mobile phase, and emerge before proteins that can enter the pores (included proteins). Proteins thus emerge from a gel filtration column in descending order of their Stokes radii.
Ref: Harper’s illustrated biochemistry. 30th edition page no: 27


Question: Hyperammonemia type I is due to deficiency of

Deficiency of any of the urea cycle enzymes result in hyperammonemia. Carbamoyl phosphate synthetase1 deficiency or hyperammonemia type 1 is comparatively rare and is characterized by severe hyperammonemia.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 205


Question: Structural proteins are

Structural Proteins : COLLAGEN is the most abundant protein in mammals and is the main fibrous component of skin , bone , tendon cailage and teeth. Different arrangements of collagen fibrils in tissues are seen. Parallel bundles in tendons and sheets layered at many angles in skin. Heat denatured collagen is GELATIN. REF :DM VASUDEVAN TEXTBOOK , EIGHTH EDITION , Page no :40 and 41


Question: Urea cycle enzymes are

Arginosuccinate synthetase is an enzyme involved. Other options are not present.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 205 .fig 15.13.


Question: In Gaucher's diseases, there is deficiency of

Glucocerebrosidase

Gaucher's disease is due to deficiency of 13-glucosidase (glucocerebrosidase).


Question: An enzyme involved in the catabolism of fructose to pyruvate in the liver is

Glyceraldehyde-3-phosphate dehydrogenase

Fructose is converted glyceroldehyde-3-phosphate which, in turn, is metabolised to pyruvate by glycolysis.
Amongst the given options, only glyceraldehyde-3-phosphate dehydrogenase is the enzyme which is involved in glycolysis after formation of glyceraldehyde-3-phosphate dehydrogenase.


Question: Insulin acts on glucose metabolism by

Insulin signals the cells of insulin-sensitive peripheral tissues, primarily skeletal muscle, to increase their uptake of glucose.Secondly, insulin acts on the liver to promote glycogenesis.Finally, insulin simultaneously inhibits glucagon secretion from pancreatic a-cells, thus signalling the liver to stop producing glucose glycogenolysis and gluconeogenesis Ref: DM Vasudevan, 7th edition, page no: 165, 318, 323

| permeability of glucose across cell membrane against glucose gradient


Question: Organelle involved in protein soing is

Protein soing, O glycosylation, and glycoproteins, oligosaccharide chain processing are the functions of the Golgi apparatus. Reference: Harper; 30th edition


Question: Protein synthesis occurs in

Synthesis of proteins are based on the grnic information present on the DNA which is transcribef into the mRNA nucleotide sequence and then translated to the amino acid sequence of the polypeptide chain. The mRNA encodes the information,tge tRNA transposthe aminoacids and ribosomes provide the platform for the protein synthesizing machinery .Transfer RNA and ribosomal RBA are transcribed from specific genes on DNA by RNA polymerases Reference:FM.VASUDEVAN Textbook SEVENTH EDITION ,Page no: 597


Question: The conversion of glutamate to glutamine is catalysed by a

Glutamine is a nutritionally non-essential amino acid It is synthesised from glutamate Free ammonia is ligated to glutamate (that is why ligase) with the use of energy provided by ATP hydrolysis. The enzyme is glutamine synthetase (Synthetase requires ATP while synthase does not require ATP).


Question: Lactose on hydrolysis yields

Lactose i. It is the sugar present in milk. It is a reducing disaccharide. On hydrolysis, lactose yields glucose and galactose. Beta glycosidic linkage is present in lactose. ii. The anomeric carbon atom of beta-galactose is attached to the 4th hydroxyl group of glucose through beta-1,4 glycosidic linkage. The lactose may be alpha or beta variety, depending on the configuration of 1st carbon of glucose moiety.Ref: DM Vasudevan, 7th edition, page no: 77

One molecule of glucose and one molecule of fructose

One molecule of glucose and one molecule of galactose


Question: Gluconeogenic capability of the cell is determined by the presence of

Fructose 1-6 biphosphatase

Glyconeogenesis refers to the synthesis of glycogen from non-carbohydrate precursors like fat or proteins, without using glucose or other carbohydrates. It should not be confused with glycogenesis which refers to the synthesis of glycogen from glucose.
Process of glyconeogenesis is same as for gluconeogenesis except for the last step, where glucose-6-phosphate enters the glycogen synthesis cycle instead of conversion into glucose.
So, glyconeogenesis and gluconeogenesis are same processes.

"The conversion of fructose 1, 6-bisphosphate to fructose-6-phosphate, for the reversal of glycolysis, is catalyzed by fructose-1, 6-bisphosphatase. Its presence determines whether a tissue is capable of synthesizing glucose, i.e. gluconeogenesis (or glycogen, i.e., glyconeogenesis) not only from pyruvate but also from triose phosphates".


Question: Primary hypercholesterolemia is

Type II A (Primary familial hypercholesterolemia)There is elevation of LDL. Patients seldom survive the second decade of life due to ischemic hea disease. The cause is LDL receptor defect. Receptor deficiency in liver and peripheral tissues will result in the elevation of LDL levels in plasma, leading to hypercholesterolemia. The LDL receptor defect may be due to the following reasons:LDL receptor deficiency.Defective binding of B-100 to the receptor. A substitution of glutamine for arginine at 3500th amino acid results in poor binding to LDL receptors. This defect is known as B-3500 or familial defective apo-B.Receptor-LDL complex is not internalised. Secondary type II hyperlipoproteinemia is seen in hypothyroidism, diabetes mellitus, nephrotic syndrome and cholestasisRef: DM Vasudevan - Textbook of Biochemistry 6th Edition 300


Question: The Z DNA helix

Z-DNA is one of the many possible double helical structures of DNA. It is a left-handed double helical structure in which the double helix winds to the left in a zig-zag pattern (instead of to the right, like the more common B-DNA form). Z-DNA is thought to be one of three biologically active double helical structures along with A- and B-DNA.

Has fewer base pairs per turn than B DNA

Is inhibited by methylation of the bases


Question: Test used for cholesterol is


Question: Xanthoproteic test is used for

Xanthoproteic test: The ring systems in phenylalanine, tyrosine and tryptophan undergo nitration on treatment with concentrated nitric acid when heated (Salkowski, 1888). The end product is yellow in color which is intensified in strongly alkaline medium. This reaction causes the yellow stain in the skin by nitric acid.Ref: DM Vasudevan, 7th edition, page no: 31


Question: If starvation exceeds 7 days, the major nutritional supply to the brain comes from

Glucose Is Always Required by the Central Nervous System and ErythrocytesErythrocytes lack mitochondria and hence are wholly reliant on (anaerobic) glycolysis and the pentose phosphate pathway at all times. The brain can metabolize ketone bodies to meet about 20% of its energy requirements; the remainder must be supplied by glucose. The metabolic changes that occur in the fasting state and starvation serve to preserve glucose and the body's limited glycogen reserves for use by the brain and red blood cells and to provide alternative metabolic fuels for other tissues.Ref: Harper&;s Biochemistry; 30th edition; Chapter 14; Overview of Metabolism & the Provision of Metabolic Fuels


Question: Amphibolic cycle is

All other pathways such as beta-oxidation of fat or glycogen synthesis are either catabolic or anabolic. But TCA cycle is truly amphibolic (both catabolic and anabolic) in nature. There is a continuous influx (pouring into) (Fig.18.9) and a continuous efflux (removal) of 4-carbon units from the TCA cycle (Fig.18.8). In a traffic circle, many roads converge and traffic flows towards one direction. Since various compounds enter into or leave from TCA cycle, it is sometimes called as "metabolic traffic circle". Impoant anabolic reactions related with citric acid cycle are a. Oxaloacetate is the precursor of aspaate b. Alpha-ketoglutarate can be made into glutamate c. Succinyl CoA is used for synthesis of heme d. Mitochondrial citrate is transpoed to cytoplasm, where it is cleaved into acetyl CoA, which then is the staing point of fatty acid synthesis


Question: Ceruloplasmin has the activity of

Whole blood contains about 100 microgram/dl of copper. Out of this, 95% is in RBC as colourless erythrocuprein. In plasma, ceruloplasmin is an impoant copper-containing protein (see Chapter 28). Normal serum level of ceruloplasmin is 25-50 mg/dl. Ceruloplasmin is a blue-colored glycoprotein (Latin "caeruleus" = blue). It is also called serum ferroxidase. It promotes oxidation of ferrous ion to ferric form, which is incorporated into transferrin. The copper atoms are tightly bound with ceruloplasmin. So copper from ceruloplasmin cannot be released easily. About 10% of copper in plasma is loosely bound with albumin, which constitutes the transpo form of copper.Ref: DM Vasudevan, page no: 428


Question: Most stable amino acid at physiological pH is

Histidine plays unique roles in enzymatic catalysis. The pKa of its imidazole proton permits histidine to function at neutral pH as either a base or an acid catalyst  without  the  need  for  any  environmentally  induced shift.
Harper's Illustrated Biochemistry 30 th edition page no 22


Question: pH is maximum in

The exocrine pancreas secretes about 1000-2500 ml of juice in 24 hours. The fluid is alkaline and contains bicarbonate and enzymes. This secretion is under the control of the hormones, Secretin and cholecystokinin. Secretin is produced under the stimulation of gastric HCl. Secretin produces a secretion with high bicarbonate content. Gastrin stimulates the production of cholecystokinin (CCK), which in turn produces pancreatic secretion rich in enzymes. The major enzymes present in pancreatic juice are amylase, lipase and proteolytic enzymes (trypsin, chymotrypsin, carboxypeptidase, elastase) as their zymogensRef: DM Vasudevan, page no: 312


Question: Urea is end product of

(Amino acid nitrogen metabolism) (241-Harper 28th) (253-Lippincott's 4th)UREA CYCLE* Urea is the end product of protein metabolism (aminoacid metabolism) and accounts for about 90% of the nitrogen containing compounds of urine. One nitrogen of urea molecule is supplied by free NH3 and other nitrogen by aspartate. Glutamate is the immediate precursor of both ammonia. The carbon and oxygen of urea are derived from CO2. urea is produced by the liver and then is transported in the blood to the kidneys for excretion in the urine* Urea cycles occurs exclusively in the cytosol, urea is produced by the hydrolysis of arginine. The cleavage of argininosuccinate does not require ATP* Carbamoyl phosphate synthase 1 (CPS-I) is the rate limiting reaction or committed step in urea synthesisOutline of Urea cycle* The Urea cycle is linked to the TCA cycle through the productin of fumarate**, Amino acid catabolism, is therefore directly coupled to energy productionMetabolic defects in Urea cycle* Hyper ammonia type ICarbamoyl phosphate synthase I* Hyperammonia type IIOrnithine transcarbamoylase* CitrullinemiaArginosuccinate synthase* Arginosuccinic aciduriaA rginosuccinase* Hyper argininemiaArginase* Dietary consumption of a protein rich meal increases the level of N-acetylglutamate in liver which enhances urea production* Excess ammonia generated from protein nitrogen is removed by urea cycle* Excess nitrogen is removed by IV phenylacetate and benzoate that conjugate with glutamine and glycine respectively (2473-74-H17th)


Question: Hemoglobin electrophoresis is based on

Ans. is 'b' i.e. charge Each of the major hemoglobin types has an electrical charge of a different degree, so the most useful method for separating and measuring normal and abnormal hemoglobins is electrophoresis. This process involves subjecting hemoglobin components from dissolved red blood cells to an electric field. The components then move away from each other at different rates, and when separated form a series of distinctly pigmented bands. The bands are then compared with those of a normal sample. Each band can be further assessed as a percentage of the total hemoglobin, thus indicating the severity of any abnormality.


Question: Riboflavin is a constituent of

Coenzymes of B-complex Vitamins* Coenzyme (abbretion) Derived from vitamin Atom or group transferred Dependent enzyme (example) Thiamine pyrophosphate (TPP) Thiamine Aldehyde or kato Transketolase Flavin mononucleotide (FMN) Riboflavin Hydrogen and electron L-Amino acid oxidase Flavin adenine dinucleotide (FAD+) Riboflavin Hydrogen and electron D-Amino acid oxidase Nicotinamide adenine dinucleotide (NAD+) Niacin Hydrogen and electron Lactate dehydrogenase Nicotinamide adenine dinucleotide phosphate (NADP+) Niacin Hydrogen and electron Glucose 6-phosphate dehydrogenase Lipoic acid Lipoic acid Hydrogen and electron Pyruvate dehydrogenase complex Pyridoxal phopsphate (PLP) Pyridoxine Amino or keto Alanine transaminase Coenzyme A (CoA) Panthothenic acid Acyl Thiokinase Tetrahydrofolate (FH4) Folic acid One carbon (formyl, methenyl etc.) Formyl transferase Biocytin Biotin CO2 Pyruvate carboxylase methylcobalamin; Deoxyadenosyl cobalamin Cobalamin methyl/isomerisation Methylmalonyl CoA mutase


Question: Enzyme specificity

Some enzymes are absolutely specific. For example, hydrolysis of urea to ammonia and carbon dioxide is catalyzed by urease. Urea is the only substrate for urease. Thiourea, though structurally similar to urea, will not act as the substrate for urease. Similarly, glucose oxidase will oxidize only beta-D-glucose and no other isomeric form. Thus, these enzymes show absolute specificity. Enzyme activity is expressed as micromoles of substrate conveed to product per minute under specified assay conditions. One standard unit (or International Unit) of enzyme activity (U) is the amount of enzyme that will conve one micromole of substrate per minute per litre of sample and is abbreted as U/L.Ref: DM Vasudevan, page no: 57

Amount of enzyme causing transformation of 1 H.mol of substrate per minute under standard conditions

Amount of enzyme required per second, per mole of product formation

Amount of enzyme binding with various substrates


Question: LCAT deficiency increases the following

* HDL is synthesized and secreted from both liver and intestine * Lecithin:cholesterol acyltransferase (LCAT) activity is associated with HDL containing apo A-I. * As cholesterol in HDL becomes esterified, it creates a concentration gradient and draws in cholesterol from tissues and from other lipoproteins thus enabling HDL to function in reverse cholesterol transpo * Absence of LCAT leads to block in reverse cholesterol transpo. HDL remains as nascent disks incapable of taking up and esterifying cholesterol. Ref:- Harper 30/e; pg num:- 249, 272


Question: Glutathione is composed of

Miester Cycle.Glutathione is composed of three aminoacids,which includes gamma-glutamate, cysteine and glycine.This is catalyzed by gamma glutamyl transferase.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 198


Question: Topoisomers are DNA form that differ in

Topoisomers are DNA form that differ in linking number Linking number Number of times one strand of DNA has to be passed through the other strand to separate both the strands completely. Its an integer for a closed circular DNA. Topoisomers are DNA forms that differ in their linking number. Topoisomerases are the enzymes which can change the linking number of DNA. Histones H2A, H2B, H3 and H4 are known as the core histones, while histones H1/H5 are known as the linker histones


Question: Conversion of norepinephrine to epinephrine occurs by

Ans. a (N-Methylation) (Ref. KDT 6th/pg. 116 and Harper biochemistry 27th/pg. 272)Cells in the adrenal medulla synthesize and secrete epinephrine and norepinephrine. The ratio of these two catechola- mines in humans is roughly 8:1, with 80% of the catecholamine output being epinephrine. Synthesis of catecholamines begins with the amino acid tyrosine, which is taken up by chromaffin cells in the medulla and converted to norepinephrine and epinephrine through the following steps:SYNTHESIS AND SECRETION OF CATECHOLAMINESSTEPS IN CATECHOLAMINE SYNTHESISCatecholamines are synthesized from the amino acid phenylalanine. Tyrosine hydroxylase is the rate limiting enzyme and its inhibition by alphamethyl-p-tyrosine results in depletion of CAs; this can be used in pheochro- mocytoma before surgery and in inoperable cases. All enzymes of CA synthesis are rather nonspecific and can act on closely related substrates, e.g. dopa decarboxylase can form 5-HT from 5-hydroxytryptophan and a methyl DA from a methyl dopa. Synthesis of NA occurs in all adrenergic neurones, while that of Adr occurs only in the adrenal medullary cells. It probably requires high cone of glucocorticoids reaching through intraadrenal portal circulation for induction of the methylating enzyme.# Secretions of Norepinephrine and epinephrine stored in electron-dense granules are stimulated by acetylcholine release from preganglionic sympathetic fibers innervating the medulla.# Many types of "stresses" stimulate such secretion, including exercise, hypoglycemia and trauma.# STEPS:- Tyrosine is transported into catecholamine-secreting neurons and adrenal medullary cells where catecholamine synthesis takes place.- The first step in the process requires tyrosine hydroxylase, which like phenylalanine hydroxylase requires tetrahydrobiopterin (HJB) as cofactor.- The hydroxylation reaction generates DOPA (3,4-dihydrophenylalanine).- DOPA decarboxylase converts DOPA to dopamine, dopamine P-hydroxylase converts dopamine to norepinephrine, and phenylethanolamine.- N-methyltransferase converts norepinephrine to epinephrine.- Tyrosine=> DOPA (HYDROXYLATION)- DOPA=> Dopamine (DECARBOXYLATION)- Dopamine=> Norepinephrine (HYDROXYLATION)- Norepinephrine=> Epinephrine (METHYLATION)# This latter reaction is one of several in the body that uses SAM (S-adenosylhomocysteine) as a methyl donor.ReceptorEffectively bindsEffect of ligand bindingAlpha-1Epinephrine, NorepinephrineIncreased free calciumAlpha-2Epinephrine, NorepinephrineDecreased cyclic AMPBeta-1Epinephrine, NorepinephrineIncreased cyclic AMPBeta-2EpinephrineIncreased cyclic AMP


Question: GLUT responsible for secretion of insulin from beta cells of pancreas

Glucose transpoer 2 (GLUT2) also known as solute carrier family 2 (facilitated glucose transpoer), member 2 (SLC2A2) is a transmembrane carrier protein that enables protein facilitated glucose movement across cell membranesGLUT2 has high capacity for glucose but low affinity (high Km, ca. 15-20 mM) and thus functions as pa of the "glucose sensor" in pancreatic b-cells. It is a very efficient carrier for glucose.Ref: DM Vasudevan, 7th edition


Question: Naf inhibits

Enolase requires Mg2++, and by removing magnesium ions, fluoride will irreversibly inhibit this enzyme. Thus fluoride will stop the whole glycolysis.Ref: DM Vasudevan, 7th edition, page no: 111


Question: Electron transpo from cytochrome &;b&; to cytochrome &;c&; is inhibited by

Site II: This involves the transfer of electrons from Cytb-Cyt-c1. This step, as well as the previous one, is bypassed in the oxidation of L-ascorbate whose electrons are directly transferred to Cyt-c. This step is blocked by BAL, Antimycin A, Hypoglycaemic drug like phenformin.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 143


Question: In glycogen, the linkage at branch points is

option c: In glycogen, the linkage at branch points is alpha-1,6 In glycogen , Linkage at straight chains alpha -1,4 branch points alpha-1,6


Question: The purpose of Lactate dehydrogenase in anaerobic glycolysis is

Replenishment of NAD is important because, it helps to sustain glycolysis in anaerobic conditions.


Question: The double bond in cholesterol structure is found in

structure of cholesterol Cholesterol is a 27-carbon compound containing a steroid nucleus, which resembles a phenanthrene ring (rings A, B, C) to which a cyclopentane ring (ring D) is attached Methyl groups are attached at carbons 10 and 13. A side chain is attached at carbon-17. A hydroxyl group is attached at carbon-3. Double bond is present in Ring B. Reference: Harper's Illustrated Biochemistry 30th Edition Pg 219


Question: Classical phenylketonuria is caused by a deficiency of

Classical phenylketonuria (hyperphenylalaninemia type I) → Deficiency of phenylalanine hydroxylase.
Atypical phenylketonuria (hyperphenylalaninemia type II and III) → Defect in dihydrobiopterin reductase.
Hyperphenylalaninemia type IV and V → Defect in dihydrobiopterin synthesis.


Question: Hemoproteins are

Conjugated protein containing <a href=" as the prosthetic group, such as <a href=" <a href=" <a href=" or <a href="


Question: Tyrosinase is

Tyrosinase is a copper-containing oxidase. It is the rate-limiting enzyme for controlling the production of melanin. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 348


Question: Atractiloside act as

Inhibitors of oxidative phosphorylation i. Atractyloside inhibits translocaseRef: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 234


Question: Biological value of proteins refers to the


Question: Zn deficiency causes

(A) (Acrodermatitis) (420- Satyanaroyan 4th)Acrodermatitis enteropathica - is a rareInherited metabolic disease of zinc deficiency caused by a defect in the absorption ofZn from the intestineZINC -- Prostate gland is very rich in Zn- Zn is mainly an intracellular element- Regarded as an Antioxidant- Gusten - a zinc containing protein of the saliva - is important for Taste sensation- Zn absorption appears to be dependent on a transport protein- Metallothionein- Zn deficiency is associated with- growth retardation, poor wound healing, anemia, loss of appetite , loss of taste sensation impaired spermatogenesis, Depression, dementia and other psychiatric disoders.Zinc containing enzymes* Superoxide dismutase (it is CU-Zn protein complex)* Carbonic anhydrase* Leucine amino peptidase* Carboxy peptide A'* Alcohol dehydrogenase *** Retinine reductase* Alkaline phosphatase* Glutamate dehydrogenase* Lactate dehydrogenase* DNA and RNA polymerase* d-ALA dehydratase


Question: Apa from occurring in nucleic acids, pyrimidines are also found in

Thiamin (vitamin B1) consists of two components: the pyrimidine moiety (4-amino-5-hydroxymethyl-2-methylpyridine) and the thiazole moiety (5-(2-hydroxyethyl)-4-methyl thiazole).The thiazole and pyrimidine moieties are biosynthesized separately and then combined to form ThMP by the action of thiamine-phosphate synthase


Question: Mitochondria havea) Plasmid DNAb) Circular DNAc) Single stranded DNAd) Double stranded DNA

Mitochondrial DNA is small circular double stranded DNA molecule.


Question: Lipogenesis in liver is stimulated by


Question: Gene amplification is by

PCR is an in-vitro DNA amplification procedure in which millions of copies of paicular sequence of DNA can be produced within a few hoursRef: DM Vasudevan, 7th edition, page no: 638


Question: Non competitive inhibition has


Question: Trinucleotide repeats found ina) Huntigton's diseaseb) Spinocerebellar ataxiac) Amyotropic lateral sclerosisd) Sclerosis

Examples of trinucleotide repeat mutation :-

Huntignton's disease
Spinocerebella ataxia
Friedreich ataxia
Fragile - X-syndrome
Dystrophia myotanica
Dentorubral pallidoluysiane atrophy
X-chromosome spinobulbar muscular atrophy


Question: In synthesis of fatty acid, energy is supplied by

An impoant point to remember is that the co-enzyme utilised for de novo synthesis is NADPH. The sources of NADPH for fatty acid synthesis are 1. Pentose Phosphate Pathway This is the main source. Tissues having active lipogenesis (liver, adipose tissue, lactating mammary gland) have an active HMP shunt pathway also. 2. Malic Enzyme Malate + NADP+ - Pyruvate + CO2 + NADPH + H+ The reaction also helps to transfer cytoplasmic oxaloacetate to the mitochondria. For every molecule of acetyl CoA delivered to the cytoplasm, one molecule of NADPH is formed and reducing equivalents are generated in cytoplasRef: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 139


Question: Keratin sulfate in urine is found in

(C) Morquio's syndrome > Hurler syndrome, also known as Mucopolysaccharidosis type I (MPSI), Hurler's disease, also Gargoylism, is a genetic disorder that results in the buildup of glycosaminoglycans (formerly known as mucopolysaccharides) due to a deficiency of alpha-L iduronidase, an enzyme responsible for the degradation of mucopolysaccharides in lysosomes.: Without this enzyme, a buildup of heparan sulfate and dermatan sulfate occurs in the body. Symptoms appear during childhood and early death can occur due to organ damage.> Hunter syndrome, or mucopolysaccharidosis Type II, is a lysosomal storage disease caused by a deficient (or absent) enzyme, iduronate-2-suifatase.> Morquio's syndrome (mucopolysaccharidosis IV or Morquio's) is an autosomal recessive mucopolysaccharide storage disease, usually inherited. It is a rare type of birth defect with serious consequences. When the body cannot process certain types of mucopolysaccharides, they build up or are eliminated, causing various symptoms.lt involves accumulation of keratan sulfate> Sanfilippo syndrome, or Mucopolysaccharidosis III (MPS-III) is a rare autosomal recessive lysosomal storage disease caused by a deficiency in one of the enzymes needed to break down the glycosaminoglycan heparan sulfate (which is found in the extra-cellular matrix and on cell surface glycoproteins).


Question: Enzyme deficiency in Cori disease is

Type Name Enzyme Deficiency Clinical Features IIIa Limit dextrinosis, Forbe or Cori disease Liver and muscle debranching enzyme Fasting hypoglycemia Hepatomegaly in infancy Accumulation of characteristic branched polysaccharide (limit dextrin) Muscle weakness Reference: Harper; 30th edition; Table: 18-2; Page no: 179


Question: Vitamin A intoxication causes injury to

Hypervitaminosis A Common in arctic explorers who eat polar bear liver Organelle damaged in hypervitaminosis is Lysosomes Acute toxicity: Pseudotumor cerebri (headache, dizziness, vomiting, stupor, and blurred vision, symptoms that may be confused with a brain tumor) and exfoliative dermatitis. In the liver, hepatomegaly and hyperlipidemia Chronic toxicity: If intake of > 50,000 IU/day for > 3 months Weight loss, anorexia, nausea, vomiting, bony exostosis, bone and joint pain, decreased cognition, hepatomegaly progresses to cirrhosis In pregnancy, retinoids cause teratogenic effects. ref DM Vasudevan 8th ed page 457


Question: Impoant intermediate product of biosynthesis of fatty acid is

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. 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: Major functions of Vitamin E in the body

The primary function of vitamin E is as an antioxidant in prevention of the nonenzymic oxidation of cell components, for example, polyunsaturated fatty acids, by molecular oxygen and free radicals. Vitamin E deficiency is almost entirely restricted to premature infants. When observed in adults, it is usually associated with defective lipid absorption or transpo. The signs of human vitamin E deficiency include sensitivity of erythrocytes to peroxide and the appearance of abnormal cellular membranes. Reference: Lippincott Textbook of Biochemistry pg no. 391

Protection of biological membrane from free radical damage