Question: Difference between High mannose & complex glycoprotein

D i.e. Presence of G1C - NAc - Gal - NANA in complex glycoprotein


Question: DNA foot printing is used to detect

Techniques of detection of DNA-Protein interaction : DNA footprinting Yeast one-hybrid system Electrophoretic mobility shift assay (EMSA)


Question: In sickle cell anemia, sickle shape occurs due to polymerization of

B. i.e. (Deoxyhemoglobin) (205 - U. satyanarayan 3rd)* Sickling is due to polymerization of deoxy HbS, Therefore if HbS is maintained in the oxygenated form (or with minimum deoxy HbS) sickling can be prevented.* The sticky patch of one deoxy HbS binds with the receptor of another deoxy HbS and this process continous resulting in the formation of long aggregate molecules of deoxy HbS. Thus the polymerization of deoxy HbS molecules leads to long fibrous precipitates these stiff fibres distort the erythrocytes into a sickle or cresent shape. The sickled erythrocytes are highly vulnerable to lysis* Basic defect in HbS is - altered solubility**


Question: Estrogen receptors are seen in

The estrogen receptor (ER) is a ligand-activated enhancer protein that is a member of the steroid/nuclear receptor superfamily.Two genes encode mammalian ER: ERa and ERb.ER binds to specific DNA sequences called estrogen response elements (EREs) with high affinity and transactivates gene expression in response to estradiolRef: DM Vasudevan, 7th edition, page no: 57


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

In liver bilirubin which is a hydrophobic compound is conjugated with glucuronic acid, to make it water soluble. The fuher transpo of bilirubin into bile is an active process Only unconjugated bilirubin elevates in neonatal/hemolytic jaundiceRef: Textbook of biochemistry for medical students, seventh edition, page no: 277

Conves a hydrophilic compound to a hydrophobic one

Conves a hydrophobic compound to a hydrophilic one

Enables the bilirubin molecule to cross the cell membrane


Question: A major lipid of mitochondrial membrane is

Inner mitochondrial membrane: The inner mitochondrial membrane is very rich in proteins and the ratio of lipid to proteins is only 0.27:1 by weight. It contains high propoion of the phospholipid cardiolipin. In contrast to outer membrane, the inner membrane is viually impermeable to polar and ionic substances. These substances enter the mitochondrion only through the mediation of specific transpo proteins.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 6


Question: Cytosolic Cytochrome C mediates

A i.e. Apoptosis Cytochrome C has two very opposite roles. Within the mitochondrial membrane it serves as electron carrier in oxidative phosphorylation. But when it leaks out into cytosol it combines with Apaf I and activates caspase-9 to mediate apoptosisQ. This dual functioning is known as moonlighting.


Question: In Familial hypercholesterolemia there is deficiency of

LDL receptors

Familial hypercholesterolemia (type IIa) is due to deficiency of functional LDL receptors as a result of different types of mutations.


Question: CAP in LAC operon is

In prokaryotes, the genes involved in a metabolic pathway are often present in a linear array called an operon, for example, the lac operonThe structural gene for b-galactosidase (lacZ) is clustered with the genes responsible for the permeation of lactose into the cell (lacY) and for thiogalactoside transacetylase (lacA). The structural genes for these three enzymes (lacZ, lacY, lacA), along with the lac promoter and lac operator (a regulatory region), are physically associated to constitute the lac operonImmediately upstream of the lac operon promoter is the binding site (CRE) for the cAMP binding protein, CAP, the positive regulator of lac operon transcriptionRef: Harper 29e, page: 430


Question: Saponification means hydrolysis of fats by

Alkali

Hydrolysis of a fat by alkali is called saponification.


Question: Krabbes&; disease is due to deficiency of

Krabbe's DiseaseAn inherited disorder of lipid metabolism, a lipid storage disease (lipidosis)Enzyme deficiency: Galactocerebrosidase (bbb-galactosidase). The enzyme normally catalyzes the hydrolysis of galactocerebrosides and it splits the linkage between ceramide and galactoseNature of lipid accumulating: Galactosylceramide Clinical manifestations:Severe mental retardation in infantsTotal absence of myelin in central nervous system Globoid bodies found in white matter of brain. Note: Galactocerebroside is an impoant component of myelin Diagnosis: Depends on the determination of galactocerebrosidase activity in leucocytes and cultured skin fibroblasts. Prognosis: Fatal.Ref: Textbook of Medical Biochemistry, Eighth Edition, Dr (Brig) MN Chatterjea, page no: 62


Question: NADPH+, H+ is generated in the reaction catalyzed by

uThe limited metabolic pathways present in red blood cells renders them completely reliant on the pentose phosphate pathway or, to be more specific, the X-linked enzyme glucose-6-phosphate dehydrogenase for the reduction of NADP+ to NADPH. uReduced NADPH is needed for the reduction of GSSG to GSH, a key intracellular antioxidant, by the enzyme glutathione reductase. uA deficiency in glucose-6-phosphate dehydrogenase renders red blood cells hypersensitive to oxidative stress. uIndividuals harboring G-6-PD deficiency are vulnerable to attacks of hemolytic anemia, resulting from the inability to generate sufficient reduced glutathione to combat episodes of oxidative stress. Harper's illustrated Biochemistry , 30th ed , page 693


Question: Protein that precipitates on heating to 45 C and redissolves on boiling is

Bence-Jones&; Protein An abnormal protein occurs in blood and urine of people suffering from a disease called multiple myeloma (a plasma cell tumour). Defined as monoclonal light chains present in the urine of patients with paraproteinaemic states. Either monoclonal `k&; or `l&; light chains are excreted in significant amounts in about 50 percent cases of multiple myeloma. It has a molecular weight 45000 and has sedimentation coefficient of 3.5 S. Sometimes the chains excreted may be a `dimer&; of L-chains. Identification--Heat Test * The protein is identified easily in urine by a simple Heat Test. On heating the urine 50 to 60oC, Bence-Jones&; proteins are precipitated, but when heated fuher it dissolves again. Reverse occurs upon cooling. * Best detected by zone electrophoresis and immunoelectrophoresis of concentrated urineRef: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 104


Question: Transcription is the synthesis of

Single stranded complimentary copy of DNA

Double stranded complimentary copy of DNA


Question: Maximum energy store in

It is the storehouse of energy in the body (about 1,35,000 kcal)The free fatty acid (FFA) mobilized from adipose tissue is the preferred fuel for muscle during starvationThe energy is stored in the concentrated form, triacylglycerol. The chylomicrons and VLDL are hydrolyzed by lipoprotein lipase present on capillary walls. It is activated by insulin.Ref: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 87


Question: NO is synthesized by

Nitric oxide is formed from Arginine by the enzyme Nitric oxide synthase.The enzyme utilizes NADPH and molecular oxygen. Citrulline is also formed.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 227


Question: Accumulation of the following causes fatty liver

Fatty liver refers to the deposition of excess triglycerides in the liver cells. The balance between the factors causing fat deposition in liver versus factors causing removal of fat from liver determines the outcomeCauses of Fatty Liver:A. Causes of fat deposition in liver1. Mobilization of NEFA from adipose tissue.2. Excess synthesis of fatty acid from glucose.B. Reduced removal of fat from liver3. Toxic injury to liver. Secretion of VLDL needs synthesis of apo B-100 and apo C.4. Decreased oxidation of fat by hepatic cells.An increase in factors (1) and (2) or a decrease in factors (3) and (4) will cause excessive accumulation, leading to fatty liverRef: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 142


Question: Introns are exised by

Introns are excised by RNA splicing by Sn-RNAs/Snurp.


Question: Most impoant in causing coronary aery disease (CAD) is


Question: Substance for gluconeogenesis is


Question: Homocystinuria is caused by deficiency of

PLP is the coenzyme for many reactions if amino acids containing sulphur. PLP plays an impoant role in methionine and cysteine metabolism. Homocysteine + Serine - Cystathionine. (Enzyme Cystathionine synthase) Cystathionine - Homoserine + Cysteine (Enzyme Cystathionase) Both these reactions require PLP. Hence in vitamin, B6 deficiency homocysteine in the blood is increased. Homocysteine level is correlated with myocardial infarction. Therefore, pyridoxine is used to prevent homocysteinemia. Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 471


Question: Components of 60 S subunit of ribosome are

The mammalian ribosome has a sedimentation consisting of 80s unitIt has larger 60s subunit and another smaller 40s subunit The larger ribosomal subunit has 28s, 5.8S, and 5S rRNA And small subunit has only 18SrRNA


Question: Cholesterol concentration is maximum in

Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 151


Question: The protein defective in cystinosis is responsible for

The protein defective in cystinosis is Cystinosin CTNS (lysosomal efflux). Clinical features:- Renal Fanconi's syndrome & Renal failure Rickets Photophobia Hypotonia Do not confuse cystinuria and cystinosis. Cystinosis is a lysosomal storage disease due defective transpo of cystine out of lysosomes.

Absorption of cysteine from renal tubules

Efflux cysteine from endoplasmic reticulum


Question: Watson and Crick model is for

Watson and crick model Double helical structure of DNA.Adjacent bases are seperated by 0.34nm. The diameter or width of the helix is 2 nanometers. Phosphate bonds form the rail of stair case. Bases jutting inside form the steps of staircase. REF :DM VASUDEVAN TEXTBOOK;8th EDITION ;Page no 557.


Question: PKU is a congenital amino acid metabolic disorder. In the following rare variants of PKU, dihydrobiopterin synthesis is affected. The enzyme deficient is

In Type 2 and 3 of PKU, there is deficiency of enzyme dihydrobiopterin reductase. Hence there is deficiency of dihydrobiopterin.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 236


Question: Insulin receptors are

Insulin receptor is a tyrosine kinase which is heterotetrameric glycoproteinRef: Essentials of Medical Pharmacology, 7th edition, KD Tripathi, page no: 261


Question: Aromatic enzyme complex is involved in the biosynthesis of

Ovarian Hormones They are C18 estrogens, C19 androgens, and C21 progesterone. These are produced by the ovarian follicles. The follicular thecal cells produce C19 androgens. These are conveed to C18 estrogens by granulosa cells, by aromatization of ring A and loss of C19 methyl group. Estradiol is the most impoant estrogen. It is conveed to estrone by liver. It is fuher hydroxylated to estriol, which is inactive. Estradiol is bound to plasma SHBG (sex hormone binding globulin). Estradiol(E2) is the predominant sex hormone present in females; however, it is present in males, at lower levels, as well. Estradiol has not only a critical impact on reproductive and sexual functioning but also affects other organs including the bones. Estradiol enters cells freely and interacts with a cytoplasmic target cell receptor. After the estrogen receptor has bound its ligand, estradiol can enter the nucleus of the target cell, and regulate gene transcription, which leads to formation of messenger RNA. The mRNA interacts with ribosomes to produce specific proteins that express the effect of estradiol upon the target cell. Estradiol binds well to both estrogen receptors, ER-alpha, and ER-beta. Selective estrogen receptor modulators (SERMs) preferentially act on one of these receptors.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 536-537


Question: Apoproteins present in LDL

LOW DENSITY LIPOPROTEINS (LDL) - LDL transpos cholesterol from liver to peripheral tissues. The only apoprotein present in LDL is apo B100. Most of the LDL paicles are derived from VLDL, but a small pa is directly released from liver. The half-life of LDL in blood is about 2 days. 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: It is used for the synthesis of other steroids like steroid hormones. Cholesterol may be incorporated into the membranes. Cholesterol may be esterified to a MUFA by acyl cholesterol acyl transferase (ACAT) for storage. The cellular content of cholesterol regulates fuher endogenous synthesis of cholesterol by regulating HMG CoA reductase. REF: DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, SIXTH EDITION, PG.NO.,153,154.


Question: Vitamin K is required for rpt Q33

The principal role of vitamin K is in the posttranslational modification of various blood clotting factors, in which it serves as a coenzyme in the carboxylation of ceain glutamic acid residues present in these proteins. Vitamin K exists in several forms, for example, in plants as phylloquinone (or vitamin K1), and in intestinal bacterial flora as menaquinone (or vitamin K2). A synthetic form of vitamin K, menadione, is available. Function of vitamin K 1. Formation of g-carboxyglutamate (GLA): Vitamin K is required in the hepatic synthesis of prothrombin and blood clotting factors II, VII, IX, and X. These proteins are synthesized as inactive precursor molecules. Formation of the clotting factors requires the vitamin K-dependent carboxylation of glutamic acid residues to Gla residues (Figure 28.26). This forms a mature clotting factor that contains GLA and is capable of subsequent activation. The reaction requires O2, CO2, and the hydroquinone form of vitamin K. The formation of GLA is sensitive to inhibition by dicumarol, an anticoagulant occurring naturally in spoiled sweet clover, and by warfarin, a synthetic analog of vitamin K. Ref: Lippincott, 5th edition, page no: 389


Question: Anion gap means

i. The sum of cations and anions in ECF is always equal, so as to maintain the electrical neutrality. Sodium and potassium together account for 95% of the cations whereas chloride and bicarbonate account for only 86% of the anions. Only these electrolytes are commonly measured.ii. Hence, there is always a difference between the measured cations and the anions. The unmeasured anions constitute the anion gap. This is due to the presence of protein anions, sulphate, phosphate and organic acids. iii. The anion gap is calculated as the difference between (Na+ + K+) and (HCO3- + Cl-). Normally this is about 12 mmol/L.Ref: D M Vasudevan 7th edition Page no: 399

Difference between high and normal anion gap acidosis


Question: Marfans Syndrome affecting eyes, skeletal system, and the cardiovascular system is caued by the mutation in the gene

Marfan Syndrome Is Caused by Mutations in the Gene for Fibrillin-1. It is inherited as an autosomal dominant trait. It affects the eyes (eg, causing dislocation of the lens, known as ectopia lentis), the skeletal system (most patients are tall and exhibit long digits and hyperextensibility of the joints), and the cardiovascular system (eg, causing weakness of the aoic media, leading to dilation of the ascending aoa). Abraham Lincoln may have had this condition. Most cases are caused by mutations in the gene (on chromosome 15) for fibrillin-1.Mutations in the fibrillin-1 gene have also been identified as the cause of acromicric dysplasia and geleophysic dysplasia, which are characterized by sho stature, skin thickening, and stiff joints. Congenital contractural arachnodactyly is associated with a mutation in the gene for fibrillin-2.Ref: Harper&;s Biochemistry; 30th edition; Chapter 50; The Extracellular Matrix


Question: The proteins presents in Deoxyribonucleic acid is

(Histone) (225 - RS 7th)DNA is a polymer of deoxyribonucleotides and is found in chromosomes, mitochondria, and chloroplasts. The nuclear DNA is bound to basic proteins called HistonesHistones - These are basic proteins rich in Arginine & Histidine


Question: Hyperammonemia impairs Citric acid cycle by depleting

Hyperammonemia, as occurs in advanced liver disease, leads to loss of consciousness, coma, and convulsions as a result of the impaired activity of the citric acid cycle, leading to reduced formation of ATP. Ammonia both depletes citric acid cycle intermediates (by withdrawing a-ketoglutarate for the formation of glutamate and glutamine) and also inhibits the oxidative decarboxylation of a-ketoglutarate. Reference: Harper; 30th edition; Page no: 161


Question: Number of ATPs produced from adipose tissue from 1 NADH (NAD+ / NADH) through respiratory chain


Question: Sumoylation of histones proteins is associated with

Sumoylation of histones is associated with Transcription repression Histone post-translational modifications & their role: Post-translational modifications Role Acetylation of histones H3 and H4 Activation or inactivation of gene transcription Acetylation of core histones Chromosomal assembly during DNA replication Phosphorylation of histone H1 Condensation of chromosomes during the replication cycle ADP-ribosylation of histone DNA repair Methylation of histone Activation and repression of gene transcription Mono-ubiquitylation Gene activation, repression, and heterochromatic gene silencing Sumoylation of histones Transcription repression


Question: Dementia, dermatitis, diarrhoea are features of

Deficiency of niacin causes pellagra, a disease involving the skin, gastrointestinal tract, and CNS.
The symptoms of pellagra progress through the three Ds: dermatitis (photosensitive), diarrhea, and dementia. If untreated, death (a fourth D) occurs.
Hartnup disorder, characterized by defective absorption of tryptophan, can result in pellagra-like symptoms.

Ref : Lippincott’s illustrated reviews for biochemistry , 7th edition.


Question: Enzymes stored in muscle is

SGOT is normally present in a number of tissues such as hea, liver, muscle, brain, and kidney. It is released into the bloodstream whenever any of these tissues get damaged. For instance, blood AST level is increased in conditions of muscle injury and hea attacks. Hence, it is not highly specific liver tissue damage indicator as it can be elevated in conditions other than liver damage. The aminotransferases catalyze the chemical reactions involving the amino acids, where an amino group is transferred from the donor amino acid to the recipient molecule. Aminotransferases are also referred to as transaminases. Another name for AST is serum glutamic oxaloacetic transaminase (SGOT). Similarly, another name for ALT is serum glutamic pyruvic transaminase (SGPT). Hence, AST is also referred to as SGOT and ALT is also referred to as SGPT. By contrast, SGPT is normally present in large concentrations in the liver. Hence, due to liver damage, its level in the blood rises, thereby, serving as a specific indicator for liver injury. To regard SGOT and SGPT as liver function tests is a misnomer that is commonly prevalent in the medical community as they do not reflect the functioning of the liver. They only detect any type of liver injury or damage done to the liver due to any type of infection and inflammatory changes. The liver may keep functioning normally even in cases when both of these enzymes are highly raised.


Question: Congenital lactic acidosis may occur d/t defect in


Question: Cholesterol from the liver is transpoed to the tissue mainly by

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. 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: It is used for the synthesis of other steroids like steroid hormones. Cholesterol may be incorporated into the membranes. Cholesterol may be esterified to a MUFA by acyl cholesterol acyl transferase (ACAT) for storage. The cellular content of cholesterol regulates fuher endogenous synthesis of cholesterol by regulating HMG CoA reductase. REF: DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, SIXTH EDITION, PG.NO.,153,154.


Question: Limiting factor for Fatty acid synthesis

Carboxylation of Acetyl CoA The first step in the fatty acid synthesis is the carboxylation of acetyl CoA to form malonyl CoA. The acetyl CoA carboxylase is not a pa of the multienzyme complex. But it is the rate-limiting enzyme. Biotin, a member of B complex vitamins, is necessary for this reaction (step 1 in Fig. 11.15). The enzyme is allosterically regulated, the major effectors being citrate (positive) and palmitoyl CoA (negative). The reaction is similar to carboxylation of pyruvate to form oxaloacetate. The elongation of the fatty acid occurs by addition of 2 carbon atoms at a time. But the 2-carbon units are added as 3-carbon, malonyl units. The whole reaction sequence occurs while the intermediates are bound to ACP (acyl carrier protein).Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 137


Question: Isocitrate dehydrogenase is linked to

There are three isoenzymes of isocitrate dehydrogenase. One, which uses NAD+, is found only in mitochondria. The other two use NADP+ and are found in mitochondria and the cytosol. Respiratory-chain-linked oxidation of isocitrate occurs through the NAD+-dependent enzyme. Reference: Harper; 30th edition; Page no: 163


Question: Creatinine is formed from

Creatinine and creatine are synthesized from glycine, arginine, and methionine. Synthesis of creatine and creatinine Creatine and creatinine are not amino acids, but specialized products of amino acids. Creatine is synthesized from glycine, arginine, and methionine. The synthesis stas with the formation of guanidinoacetate from glycine and arginine in the kidney. Fuher reactions take place in the liver and muscle. REF: Lippincott book of biochemistry 6th ed.


Question: Cation used in PCR is

All polymerases require divalent cations for their activity but some tend to function in buffers containing Mn2+ as well, although a little less efficiently.dNTPs and oligonucleotides bind to Mg2+ and therefore its concentration should exceed the molar concentration of phosphate groups that are contributed from both the dNTPs and primers.dNTPs bind in equimolar concentration with Mg2+.


Question: The enzyme marker of electron transpo system is

Complex III: CoQ-Cyt.C Reductase Functions as * Proton pump, and * Catalyses transfer of electrons SECTION TWO This system catalyses transfer of electrons from CoQ.H2 to Cyt-c Cyt-b and Cyt-c1. The electrons from CoQ.H2 is first accepted by Cyt-b566 and then transferred to Cyt-b562, which reduces Co.Q.H2 CoQ Fe+++ accepts electron and is oxidised to Fe++. The system also acts as a proton pump. It is believed that 4 (four) protons are pumped across the mitochondrial membrane during the oxidation. The energy change permits ATP formation (Site II). Role of Q cycle and Rieske FeS in complex III Electrons are passed from Q.H2 to cytochrome C complex III-Q cytochrome C oxidoreductase: Q. H2 + 2 Cyt C + 2H+ - Q + 2 CytC + 4H+ Oxidised matrix reduced membrane space The process is believed to involve cytochromes C1, b1 and bHH and a Rieske FeS. Rieske FeS is an unusual FeS in which one of the Fe atoms is linked to two histidine -SH groups rather than two cysteine -SH groups and is called as the Q cycle. Q may exist in three forms: * Oxidised quinone, * Reduced quinol, or * Semiquinone. The semiquinone is formed transiently during the cycle, one turn of which results in the oxidation of 2Q.H2 to Q, releasing 4H+ into the intermembrane space, and the reduction of one Q to QH2, causing 2H+ to be taken up from the matrix. Note It is to be noted that while Q carries two electrons, the cytochromes carry only one, thus the oxidation of one Q.H2 is coupled to the reduction of two molecules of cytochrome C the Q. cycle. Other options are not paicipating in ETC.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 142


Question: The dietary fats are transmitted from GIT to adipocytes in the form of

TG derived from intestinal absorption of fats are transpoed in the blood as a lipoprotein complex called chylomicrons. Chylomicrons are small microscopic paicles of fats, about 1m in diameter and are responsible for transpo of exogenous (TG) in the blood. * Similarly, TG that are synthesised in Liver cells is conveed to lipoprotein paicles, called very low-density lipoproteins (VLDL) and thrown into the circulation. VLDL is mainly concerned with transpo of endogenous TG. In addition to above: * Fatty acids released from adipose tissue by hydrolysis of TG are thrown in the circulation as free fatty acid (FFA). They are carried in non-esterified state in plasma, hence also called NEFA. In circulation, FFA/ NEFA combines with albumin and are carried as albumin-FFA complex. Some 25 to 30 mols of FFA are present in combination with one mol. of albumin.Ref: Textbook of Medical Biochemistry 8th Edition Dr (Brig) MN Chatterjea, Rana Shinde page no: 445


Question: Stored triacylglycerol and cholesterol are released by

Lipolysis The prevailing state of high glucagon-insulin ratio stimulates cAMP-mediated lipolysis by increasing the activity of hormone-sensitive lipase. Then skeletal muscle, hea, and kidney will shut down their glucose utilization; and will depend mainly on fatty acids for energy needs (glucose-fatty acid cycle). Inactivation of pyruvate dehydrogenase by phosphorylation is the basis of this change. The stimulation of the activity of CAT by glucagon ors increased rate of beta-oxidation. The increased rate of lipolysis and beta-oxidation provides an alternate source of fuel as acetyl CoA and subsequently ketone bodies. Ketone bodies provide fuel fortissues like hea muscle, skeletal muscle and to some extent the brain. It is seen that brain stas utilizing ketone bodies from 3rd day of starvation. By 10th day of starvation, about 60% of energy for brain is derived from ketone bodies. The cyclic AMP-mediated activation cascade enhances the intracellular hormone-sensitivelipase (Fig. 11.16 and Table 11.4). The phosphorylated form of the enzyme is active which acts on TAG and liberates fatty acids. iii. Under conditions of starvation, a high glucagon, ACTH, glucocoicoids and thyroxine have lipolytic effect. The released free fatty acids (FFA) are taken up by peripheral tissues as a fuel. Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 89,140


Question: The most common lysosomal storage disorder is

Ans. (a) Gaucher's diseaseRef: Harper's Biochemistry, 30th ed. pg. 251LYSOSOMAL STORAGE DISEASE* Lyzosomal storage disorders are a group of approximately 50 rare inherited metabolic disorders that result from defects in lysosomal function.* Lysosomal storage disorders are caused by lysosomal dysfunction usually as a consequence of deficiency of a single enzyme required for the metabolism of lipids, glycoproteins (sugar containing proteins) or so-called mucopolysaccharides.* Gaucher's disease is the most common of the lysosomal storage diseases. It is a form of sphingolipidosis (a subgroup of lysosomal storage diseases), as it involves dysfunctional metabolism of sphingolipids.* The disorder is characterized by bruising fatigue, anemia, low blood platelets, and enlargement of the liver and spleen.


Question: Strongest interactions among the following

Strongest bond - CovalentWeakest bond - Van der wals forcesMoleucular interactionsThere are two types of interactions between molecules that stabilize molecular structures :-i) Covalent bonds, e.g. peptide bonds and disulphide bonds.i) Non-covalent bonds.


Question: RNA polymerase is

Ans. is 'a' i.e., DNA dependent RNA polymerase The major enzyme involved in transcription (i.e. synthesis of DNA to RNA) is RNA polymerase.It is DNA dependent RNA polymerase.DNA dependent DNA polymerase DNA plymerase (In DNA replication)DNA dependent RNA polymerase - RNA polymerase (In transcription)RNA dependent DNA polymerase -> Reverse transcripatase (In reverse transcription)


Question: The enzyme defect in galactosemia is

Inability to metabolize galactose occurs in the galactosemias, which may be caused by inherited defects of galactokinase, uridyl transferase, or 4-epimerase Though deficiency of uridyl transferase is best known.Harper 30th edition pg: 205


Question: Malate shuttle is important in

Most of the guides have given glycolysis as the answer. According to me, which is incorrect.
The most important function of malate shuttle is to transport cytosolic reducing equivalents (generated in glycolysis) into the mitochondria.
But, malate shuttle has no direct role in the occurrence of any reaction of glycolysis, i.e. malate shuttle does not take part in the glycolytic process itself. Its role is to generate ATP by transporting NADH into the mitochondria.
You can easily understand this by the fact that anaerobic glycolysis occurs without any participation of the malate shuttle. Hence, presence or absence of malate shuttle has no direct effect on the glycolytic process itself.
On the other hand, the malate shuttle is directly involved in gluconeogenesis by transporting malate out of the mitochondria into the cytosol. Thus without malate shuttle, gluconeogenesis cannot occur.
Thus, malate shuttle is a part of the gluconeogenic process while it is not a part of the glycolytic process.
In short
Most important function of malate shuttle is to transport the reducing equivalents (generated in glycolysis) into the mitochondria.
Malate shuttle is not a part of the glycolytic process itself
Malate shuttle is a part of the gluconeogenic process.


Question: The inhibitor of complex IV of electron transpo chain is

Complex IV inhibitors i. Carbon monoxide inhibits cellular respiration ii. Cyanide (CN-) iii. Azide (N3-) iv. Hydrogen sulphide (H2S)Ref: MN Chatterjea Textbook of Medical Biochemistry, 6th edition, page no: 234


Question: Reducing equivalents produced in glycolysis are transpoed from cytosol to mitochondria by

Malate-Aspaate Shuttle Mitochondrial membrane is impermeable to NADH. The NADH equivalents generated in glycolysis are therefore to be transpoed from the cytoplasm to mitochondria for oxidation. This is achieved by malate-aspaate shuttle or malate shuttle, which operates mainly in the liver, kidney, and hea. The cycle is operated with the help of enzymes malate dehydrogenase (MDH) and aspaate aminotransferase. From one molecule of NADH in the mitochondria, 2 1/2 ATP molecules are generated.Ref: DM Vasudevan, 7th edition, page no: 260


Question: Prader willi syndrome and Angel man syndrome are examples of

Genomic imprinting is a proces of epigenetic modification of nucleotides in which only one allele of specific gene is functioning, while the other allele is silenced based on the parent of origin.


Question: The conversion of propionyl CoA to succinyl CoA requires the following vitamins/coenzymes

Propionate is a major precursor of glucose in ruminants; It enters gluconeogenesis the citric acid cycle. After esterification with CoA, propionyl-CoA is carboxylated to d-methylmalonyl-CoA, catalyzed by propionyl-CoA carboxylase, a biotin-dependent enzyme.l-methylmalonyl-CoA undergoes isomerization to succinyl-CoA catalyzed by methylmalonyl-CoA mutase. Methylmalonyl-CoA mutase is a vitamin B12-dependent enzyme, and in deficiency methylmalonic acid is excreted in the urine (methylmalonic aciduria).Ref: Harper&;s Biochemistry; 30th edition; Chapter 19; Gluconeogenesis & the Control of Blood Glucose


Question: A glycoprotein that regulates folding of proteins that are expoed from the cell is

Glycoproteins Calnexin and Calreticulin regulate folding of proteins that are expoed from the cellRef: Harper&;s biochemistry; 30th edition; Chapter 46; Glycoproteins


Question: Two solutions with equal osmotic pressures are

Ans: a (Isotonic solution) Ref: Gcmong 22nd ed/p.5Osmosis: - The diffusion of solvent molecules into a region in which there is a higher concentration of a solute to which the membrane is imperme-able.Osmotic pressure: - The pressure necessary to prevent solvent migration is the osmotic pressure of the solution.


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

Usually, purine and pyrimidine are found in nucleic acids (DNA and RNA) as a part of nucleotides.
Pyrimidines also occur in thiamine (vitamin B1) and alloxan.
Purine is also a structural component of a number of essential coenzymes, e.g. coenzyme-A, NAD+, NADP+ and FAD+.


Question: Cataract in diabetes is caused by

B. i.e. (Sorbitol) (186 - Harper 27th) (280- U-satyanarayan 3rd)Sorbitol Pathway in Diabetes MellitusIn uncontrolled diabetes (hyperglycemia) large amounts of glucose enter the cells which are not dependent on insulin. Significantly the cells with increased intracellular glucose levels in diabetes (lens, retina, nerve cells, Kidney etc) possess high activity of aldolase reductase, and sufficient supply of NADPH. This results in a rapid and efficient conversion of glucose to sorbitol. The enzyme sorbitol dehydrogenase however is eithr low in activity or absent in these cells, hense sorbitol is not converted to fructose. Sorbitol cannot freely pass through the cell membrane, and accumulate in the cells where it is produced. Sorbitol due to its hydrophilic nature- causes strong osmotic effects leading to swelling of the cells. Some of the pathological changes associated with diabetes (like Cataract formation, peripheral neuropathy, nephropathy) are believed to be due to the accumation of sorbitol)* Cataract in a diabetic is caused by sorbitol which is formed by interaction on glucose by - Aldolase reductase*** Essential fructosuria - due to deficiency of enzyme fructokinae** Hereditary fructose intolerance- is due to absence of enzyme - aldolase - B*** Essential pentosuria - deficiency of xylitol- dehydrogenase**


Question: Biosynthesis of glucuronic acid requires the

Glucuronic acid is a sugar acid derived from glucose, with its sixth carbon atom oxidized to a carboxylic acid. In living beings, this primary oxidation occurs with UDP-a-D-glucose (UDPG), not with the free sugar.Ref: DM Vasudevan, 7th edition, page no: 120


Question: Urea cycle enzymes area) Glutaminaseb) Asparaginasec) Argininosuccinate synthetased) Ornithine transcarboxylasee) Glutamate dehydrogenase

Enzymes involved in the urea cycle are carbamoyl phosphate synthetase-I, ornithine transcarbamylase, argininosuccinate synthase, arginosuccinase, and arginase.
Read the option 'd' carefully, it is ornithine transcarboxylase (not ornithine transcarbamylase, which is involved in urea cycle).
I am not sure whether both are the same enzyme or not as no textbook has mentioned this. But according to the following statement, ornithine transcarboxylase is involved in the urea cycle:-

"With the exception of X-linked ornithine transcarboxylase deficiency, urea cycle disorders are inherited in an autosomal recessive fashion".

And all textbooks have mentioned that all urea cycle disorders are autosomal recessive, except for ornithine transcarbamylase deficiency, which is X-linked disorders.
Thus, my interpretation is that both are same.


Question: HDN is seen due to deficiency of vitamin

Vit k is necessary for coagulation. Factors dependent on Vit k are synthesised on the liver as inactive zymogen. They undergo gamma carboxylation, which requires Vit k as a cofactor. Clinical Manifestations of Deficiency i. Hemorrhagic disease of the newborn is attributed to vitamin K deficiency. The newborns, especially premature infants have relative vitamin K deficiency. This is due to lack of hepatic stores, limited oral intake (breast milk has very low levels, 15 mg/litre) and absence of intestinal bacterial flora. ii. It is often advised that pre-term infants be given prophylactic doses of vitamin K (1 mg Menadione iii. In children and adults, Vitamin K deficiency may be manifested as bruising tendency, ecchymotic patches, mucous membrane haemorrhage, post-traumatic bleeding Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 462


Question: The absorption of dietary triglycerides from the gut is mainly as


Question: Type 2 hypercholesterolemia occurs due to

Type II A(Primary familial hypercholesterolemia) There is elevation of LDL. Patients seldom survive the second decade of life due to ischemic hea disease (Table 25.4). 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 3500thamino 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 cholestasis


Question: Enzyme involved in Variegate porphyria

Enzyme InvolvedType Major Signs and SymptomsResults of Laboratory TestsProtoporphyrinogen oxidaseVariegate porphyria (hepatic)Photosensitivity, abdominal pain,neuropsychiatric symptomsUrinary ALA, PBG, and coproporphyrinIII and fecal protoporphyrinIX increasedRef: Harper&;s Biochemistry; 30th edition; Chapter 31 Porphyrins & Bile Pigments


Question: In competitive inhibition, the relation Km and Vmax is one of the following

Competitive inhibitors increase Km by interfering with the binding of the substrate they do not affect VmaxIn non-competitive inhibition Km doesn&;t change because Km is a measure of the enzyme for its substrate, here Vmax decreases


Question: Abnormal base in tRNA is

The D Arm or DHU region is so named due to the presence of a dihydrouridine in that areaThe DHU arm serves as the recognition site for the enzyme which adds the amino acidRef: DM Vasudevan, 7th edition, page no: 597


Question: PKU is a congenital amino acid metabolic disorder. In one of the following rare variants of PKU Dihydro Biopterin synthesis is affected. The enzyme deficient is

Atypical form of phenylketonuria is due to deficiency of dihydrobiopterin reductase which is required for converion of H2-biopterin intorin. H4-biopterin is required for oxidation of phenylalanine because it is a cofactor for phenylalanine hydroxylase.


Question: Cholesterol levels in abnormal person should be preferably less than


Question: The structure of Phospholipid consists of

Phospholipid - 2 Fatty acid+ Glycerol+ PO + Choline or ethanolamine ( 2 Fatty acid + Glycerol is called Diacylglycerol or Diglyceride) Reference: Harpers illustrated biochemistry 31st edition page196


Question: Not seen in alpha helix

a-Helix: A peptide chain forms regular helical coils called a-helix. These coils are stabilized by hydrogen bonds between carbonyl O of 1st amino and amide N of 4th amino acid residues. Thus in a-helix intrachain hydrogen bonding is present. The a-helices can be either right handed or left handed. Left-handed a-helix is less stable than right-handed a-helix because of the steric interference between the C = O and the side chains. Only the right-handed a-helix has been found in protein structure. Each amino acid residue advances by 0.15 nm along the helix, and 3.6 amino acid residues are present in one complete turn. The distance between two equivalent points on turn is 0.54 nm and is called a pitch. Small or uncharged amino acid residues such as alanine, leucine, and phenylalanine are often found in a-helix. More polar residues such as arginine, glutamate, and serine may repel and destabilize a-helix. Proline is never found in a aa aa-helix. The proteins of hair, nail, skin contain a group of proteins called keratins rich in a aa aa-helical structureRef: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 89


Question: In oxidative phosphorylation, the ATP production and respiratory chain are linked by

The chemiosmotic coupling hypothesis is the most accepted theory which explains the mechanism of oxidative phosphorylation.
The theory states that free energy of electron transport is conserved by pumping protons (111 from mitochondrial matrix to the intermembrane space, so as to create an electrochemical proton gradient across the inner mitochondrial membrane. The electrochemical potential of this gradient is used to synthesize ATP.


Question: Hybridoma cell line is a product of fusion

The B cells are mixed with mouse myeloma cells and exposed to polyethylene glycol, which causes cell fusion. The product of this fusion is a permanentcell line called a hybridoma capable of providing a continuous supply of monoclonal antibodies.Ref: Harper&;s biochemistry; 30th edition; Chapter 52; 52 Plasma Proteins & Immunoglobulins


Question: Fluoroacetate inhibits

Fluoroacetate is similar to acetate, which has a pivotal role in cellular metabolism. disrupts the citric acid cycle (also known as the Krebs cycle) by combining with coenzyme A to form fluoroacetyl CoA, which reacts with citrate synthase to produce fluorocitrate which binds very tightly to aconitase, thereby halting the citric acid cycle. This inhibition results in an accumulation of citrate in the blood. Citrate and fluorocitrate are allosteric inhibitors of phosphofructokinase-1 (PFK-1), a key enzyme in the breakdown of sugars. When PFK-1 is inhibited, cells are no longer able to metabolize carbohydrates, depriving them of energy.Ref: DM Vasudevan, 7th edition


Question: Proteins are soed by

Because of the complex internal organization of The first step in protein soing takes place while , the , and secretion from the cell are synthesized on The endoplasmic reticulum, Golgi apparatus, and lysosomes are thus distinguished from other cytoplasmic organelles by their common involvement in protein processing and connection by vesicular transpo.Ref: DM Vasudevan, 7th edition, page no: 605


Question: NADPH is produced by


Question: The most impoant source of reducing equivalents for fatty acid synthesis in the liver is

The oxidative reactions of the pentose phosphate pathway(HMP pathway) are the chief source of the hydrogen required for the reductive synthesis of fatty acids. NADPH is involved as a donor of reducing equivalents.Glycolysis is the metabolic pathway that conves glucose C6H12O6, into pyruvate, CH3COCOO- + H+. The free energy released in this process is used to form the high-energy molecules ATP (adenosine triphosphate) and NADH (reduced nicotinamide adenine dinucleotide)The citric acid cycle is the final pathway for the oxidation of carbohydrate, lipid, and protein. Their common end metabolite, acetyl-CoA, reacts with oxaloacetate to form citrate. By a series of dehydrogenations and decarboxylations, citrate is degraded, reducing coenzymes, releasing two CO2, and regenerating oxaloacetate.The reduced coenzymes are oxidized by the respiratory chain linked to the formation of ATP. Thus, the cycle is the major pathway for the formation of ATP and is located in the matrix of mitochondria adjacent to the enzymes of the respiratory chain and oxidative phosphorylation. The uronic acid pathway is an alternative pathway for the oxidation of glucose that does not provide a means of producing ATP but is utilized for the generation of the activated form of glucuronate, UDP-glucuronate which is mainly used for detoxification of foreign chemicals and for the synthesis of Mucopolysaccharides. The utilized glucuronate produced in this pathway is conveed to xylulose 5-p which is fuher metabolized through HMP pathway.The pentose phosphate pathway (also called the phosphogluconate pathway and the hexose monophosphate shunt) is a metabolic pathway parallel to glycolysis. It generates NADPH and pentoses (5-carbon sugars) as well as ribose 5-phosphate, the last one a precursor for the synthesis of nucleotides. While it does involve oxidation of glucose, its primary role is anabolic rather than catabolic.There are two distinct phases in the pathway. The first is the oxidative phase, in which NADPH is generated, and the second is the non-oxidative synthesis of 5-carbon sugars. For most organisms, the pentose phosphate pathway takes place in the cytosolRef: Harpers biochemistry 30th edition; page no-234


Question: Denaturation of double stranded DNA involves


Question: The following enzyme defect causes acute intermittent porphyria

The defective enzyme in acute intermittent porphyria is hydroxymethylbilane synthase (uroporphyrinogen I synthase)ALA and porphyrobilinogen accumulate in body tissues and fluids.It is an autosomal dominant disorder.While most porphyrias are inherited in an autosomal dominant manner, congenital erythropoietic porphyria is inherited in a recessive mode. The defective enzyme in congenital erythropoietic porphyria is uroporphyrinogen III synthase,Harper 30th edition pg: 329


Question: Enzyme deficiency in Farber disease is

DiseaseEnzyme deficiencyClinical symptomsTay-Sachs diseaseHexosaminidase AMental retardation, blindness, muscular weaknessFabry diseasea-GalactosidaseSkin rash, kidney failure (full symptoms only in males;X-linked recessive)MetachromaticleukodystrophyArylsulfatase AMental retardation and psychologic disturbances inadults; demyelinationKrabbe diseaseb-GalactosidaseMental retardation; myelin almost absentGaucher diseaseb-GlucosidaseEnlarged liver and spleen, erosion of long bones,mental retardation in infantsNiemann-PickdiseaseSphingomyelinaseEnlarged liver and spleen, mental retardation;fatal in early lifeFarber diseaseCeramidaseHoarseness, dermatitis, skeletal deformation,mental retardation; fatal in early lifeRef: Harper&;s Biochemistry; 30th edition; Chapter 24 Metabolism of Acylglycerols & Sphingolipids


Question: Treatment of Multiple Carboxylase deficiency is

Multiple carboxylase deficiencies is characterized by deficient activities of three biotin-dependent enzymes, propionyl coenzyme A carboxylase, pyruvate carboxylase, and beta-methylcrotonyl coenzyme A carboxylase. Multiple carboxylase deficiencies is a form of metabolic disorder involving failures of carboxylation enzymes. The deficiency can be in biotinidase or holocarboxylase synthetase. These conditions respond to biotin. Forms include Holocarboxylase synthetase deficiency - neonatal; Biotinidase deficiency - late onset; If left untreated, the symptoms can include feeding problems, hypotonia, generalized erythematous rash with skin exfoliation and alopecia, failure to thrive, seizure, coma, developmental delay, foul-smelling urine, metabolic acidosis, ketosis, and hyperammonemia.


Question: Carboxylation is governed by

Coenzyme role of Biotin Play a role in gene expression, fatty acid synthesis, gluconeogenesis and serve as a CO2 carrier for Carboxylases enzymes and gene regulation by histone biotinylation. Coenzyme for ATP dependent Carboxylation reaction (Carbon Dioxide Fixation) Pyruvate Carboxylase (Pyruvate to Oxaloacetate) Propionyl CoA Carboxylase (Propionyl CoA to Methyl Malonyl CoA) Acetyl CoA Carboxylase (Acetyl CoA to Malonyl CoA) Methyl Crotonyl CoA Carboxylase ref DM Vasudevan 8th ed page 473


Question: The major driving force for formation of membrane lipid bilayer is

The molecules align themselves to form monolayers with the polar heads pointing in one direction and the nonpolar tails in the opposite direction (Figs 7.7A and B). Only fatty acids with more than 6 carbon atoms form monolayers. This explains their role as components of biomembranes The self-assembly of phospholipids into bilayers is driven by hydrophobic interaction. They also act as detergents and emulsifying agents. In vivo, they act as pulmonary surfactants.Ref: DM Vasudevan, page no: 79


Question: Hunter syndrome is due to deficiency of


Question: Pancreatic secretions are a rich source of

Phospholipase A2 (PLA2) is elevated in cases of acute pancreatitis. Pancreatic sPLA2 serve for the initial digestion of phospholipid compounds in dietary fat. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 174


Question: Nucleic acid absorbs light at wavelength of 260 mm due to

DNA bases (purines and pyrimidines) absorb UV light of 260 nm.


Question: Micro RNA is transcribed bya) RNA polymerase Ib) RNA polymerase IIc) RNA polymerase IIId) DNA Polymerasee) Drosha

Micro RNA (mi-RNA) are typically 21-25 nucleotides in length and are generated by nucleolytic processing of the products of distinct genes/transcription units. These precursors are single-stranded but have extended intramolecular secondary structure.
Most mi-RNA are processed from RNA polymerase II transcripts of severed hundred to thousands of nucleotides in length called Pri-miRNA (primary transcript). Within these long transcripts are sequency that fold into a hairpin structure. A nuclear RNAase specific for dsRNA called Drosha acts with a nuclear ds-RNA binding protein called DGCR in human (Pasha in Drosophila) and cleaves the hairpin region out of long precursor RNA generating a pre-miRNA.


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

Convergence is an evolutionary process by which distinctly unrelated organisms (protein) acquire morphologically similar traits (function), whereas divergence produces different traits (functions) in related same ancestor organisms (proteins).


Question: Choose the major fuel that is being used by the chest muscles used during weightlifting.

We will illustrate, in addition, how biochemical measurements can pinpoint a disorder and allow one to determine which enzyme is functioning improperly.a. Mouth(1). Salivary glands produce a-amylase, which cleaves a-1,4 bonds between glucose residues in dietary starch. (Pancreatic a-amylase catalyzes the same reaction.)b. Stomach(1). Chief cells produce the proteolytic enzyme pepsin, as its inactive precursor pepsinogen. Pepsin digests proteins.(2). Parietal cells produce hydrochloric acid (HCl) and intrinsic factor.(a). HCl causes pepsinogen (the precursor of pepsin) to cleave itself (autocatalysis), producing pepsin.(b). Intrinsic factor binds dietary vitamin B12 and aids in its absorption.(c). Vitamin B12 is the cofactor for the conversion of homocysteine to methionine and methyl malonyl-CoA to succinyl-CoAc. Gallbladder(1). Bile salts, synthesized in the liver from cholesterol, pass through the gallbladder into the intestine, where they aid in lipid digestion.(2). Bilirubin diglucuronide, produced in the liver from bilirubin (the excretory product of heme degradation), passes through the gallbladder into the intestine.d. Pancreas(1). The pancreas produces bicarbonate (HCO3- ), which neutralizes stomach acid as it enters the intestinal lumen. The subsequent increase in pH in the lumen allows more extensive ionization of bile salts (so they serve as better detergents) and increases the activity of digestive enzymes.(2). The pancreas produces digestive enzymes (e.g., trypsin, chymotrypsin, the carboxypeptidases, elastase, a-amylase, lipase).(3). The B (or b) cells of the endocrine pancreas produce insulin (the hormone that stimulates the storage of fuels in the fed state) and the A (or a) cells produce glucagon (the hormone that stimulates the release of stored fuels during fasting).e. Intestine(1). The enzymes from the exocrine pancreas digest food in the intestinal lumen.(2). The intestinal digestive enzymes are bound to the brush borders of intestinal epithelial cells (aminopeptidases, dipeptidases and tripeptidases, lactase, sucrase, maltases, and isomaltases).(3). The absorption of digestive products occurs through the intestinal epithelial cells.(4). The intestinal epithelial cells produce chylomicrons from the digestive products of dietary fat (fatty acids and 2-monoacylglycerols) and secrete the chylomicrons into the lymph.(5). Most bile salts are resorbed in the ileum and recycled by the liver. Only 5% are excreted in the feces. This excretion of bile salts, along with cholesterol secreted by the liver into the gut via the gallbladder, is the major means by which the body disposes of the cholesterol ring structure (sterol nucleus).f. Liver (the enzymic regulation of liver function is summarized in Tables below)(1). Functions of the liver include:(a). Storage of glycogen produced from dietary carbohydrate.(b). Synthesis of very low-density lipoprotein (VLDL), mainly from dietary carbohydrate.(c). Production of high-density lipoprotein, which transfers CII and E apolipoproteins to chylomicrons and VLDL, converts cholesterol to cholesterol esters (via the lecithin-cholesterol acyltransferase reaction), and reduces blood by which cholesterol and cholesterol esters are transported from tissues to the liver (reverse cholesterol transport).(d). Maintenance of blood glucose levels during fasting via glycogenolysis and gluconeogenesis.(e). Production of urea from nitrogen derived, in part, from amino acids because they are being converted to glucose (via gluconeogenesis) during fasting.(f). Production of ketone bodies from fatty acids derived from lipolysis of adipose triacylglycerols during fasting.(g). Synthesis of cholesterol (which is also made in other tissues).(h). Conversion of cholesterol to bile salts.(i). Production of many blood proteins (e.g., albumin, blood-clotting proteins).(j). Production of purines and pyrimidines, which are transported to other tissues via red blood cells.(k). Degradation of purines (to uric acid) and pyrimidines (to CO2 , H2 O, and ammonia).(l). Oxidation of drugs and other toxic compounds via the cytochrome P450 system.(m). Conjugation of bilirubin and excretion of bilirubin diglucuronide into the bile.(n). Oxidation of alcohol via alcohol and acetaldehyde dehydrogenases and the microsomal ethanol-oxidizing system (MEOS).(o). Synthesis of creatine (from guanidinoacetate), which is used to produce creatine phosphate, mainly in the muscle and brain.(p). Conversion of dietary fructose to glycolytic intermediates.(2). If liver cell function is compromised (e.g., in viral hepatitis or alcoholic cirrhosis):(a). NH4+ , which is toxic (particularly to the central nervous system), increases in the blood.(b). The BUN level decreases because the liver has a decreased capacity to produce urea.(c). Blood glucose decreases because of decreased glycogenolysis and gluconeogenesis.(d). Blood cholesterol levels decrease owing to an inability to produce and secrete VLDL.(e). The production of bile salts decreases.(f). Bilirubin levels increase in the body (causing jaundice) because of reduced conjugation with glucuronic acid.(g). Lysis of damaged liver cells allows enzymes to leak into the blood.1. Lactate dehydrogenase increases.2. Alanine aminotransferase increases.3. Aspartate aminotransferase increases.4. Alkaline phosphatase increases.(h). Chronic liver problems result in decreased protein synthesis.1. Serum proteins (e.g., albumin) decrease.2. VLDL production decreases because of decreased apolipoprotein B-100 and triacylglycerols accumulate in the liver. A fatty liver results.g. Brain(1). Glucose is the major fuel for the brain.(2). The brain can use ketone bodies, but only after 3 to 5 days of fasting when blood ketone body levels are elevated.(3). The brain needs energy to think (i.e., memory involves RNA synthesis), conduct nerve impulses, synthesize neurotransmitters, and so on.h. Red blood cells(1). Red blood cells lack mitochondria, so they have no TCA cycle, b-oxidation of fatty acids, electron transport chain, and other pathways that occur in the mitochondria.(2). Glucose is the major fuel for red blood cells.(a). Glucose is converted to pyruvate and lactate.(3). Red blood cells carry bases and nucleosides from the liver to other tissues.(4). The major function of red blood cells is to carry O2 from the lungs to the tissues and to aid in the return of CO2 from the tissues to the lungs.i. Adipose tissue(1). The major fuel of adipose tissue is glucose.(2). Insulin stimulates the transport of glucose into adipose cells.(3). The function of adipose tissue is to store triacylglycerol in the fed state and release it (via lipolysis) during fasting.(a). In the fed state, insulin stimulates the synthesis and secretion of lipoprotein lipase (LPL), which degrades the triacylglycerols of chylomicrons and VLDL in the capillaries. Fatty acids from these lipoproteins enter adipose cells and are converted to triacylglycerols and stored. Glucose provides the glycerol moiety. (Glycerol is not used because adipose cells lack glycerol kinase.)(b). During fasting, adipocyte triglyceride lipase and hormone-sensitive lipase (phosphorylated and activated via a cAMP-mediated mechanism) initiate lipolysis in adipose cells.j. Muscle(1). Muscle uses all fuels that are available (glycogen stores, and fatty acids, glucose, ketone bodies, lactate, and amino acids from the blood) to obtain energy for contraction.(2). During fasting, muscle protein is degraded to provide amino acids (particularly alanine) for gluconeogenesis.(3). Creatine phosphate transports high-energy phosphate from the mitochondria to actinomyosin fibers and provides ATP for muscle contraction.(4). Creatinine is produced nonenzymatically from creatine phosphate, and a constant amount (dependent on the body muscle mass) is released into the blood each day and excreted by the kidneys.(5). Muscle glycogen phosphorylase differs from liver phosphorylase but catalyzes the same reaction (glycogen+Pi-glucose-1-phosphate).(6). Insulin stimulates the transport of glucose into muscle cells.k. Heart(1). The heart is a specialized muscle that uses all fuels from the blood.(2). The muscle-brain (MB) isozyme of CK is found in heart muscle. Its release can be used to monitor a heart attackl. Kidney(1). The kidney excretes substances from the body via the urine, including urea (produced by the urea cycle in the liver), uric acid (from purine degradation), creatinine (from creatine phosphate), NH4+ (from glutamine via glutaminase), H2SO4 (produced from the sulfur of cysteine and methionine), and phosphoric acid.(2). Daily creatinine excretion is constant and depends on the body muscle mass. It is used as a measure of kidney function (the creatinine-clearance rate).(3). Glutaminase action increases during acidosis and produces NH3 , which enters the urine and reacts with H+ to form NH4+ . NH4+ buffers the urine and removes acid (H+) from the body.(4). Uric acid excretion is inhibited by lead (Pb) and metabolic acids (ketone bodies and lactic acid). High blood uric acid can result in gout. Gout can be caused either by increased production or by decreased excretion of uric acid. Deficiency of the base salvage enzyme hypoxanthine guanine phosphoribosyl transferase in Lesch-Nyhan syndrome results in increased production of uric acid.(5). Kidney dysfunction can lead to increased BUN, creatinine, and uric acid in the blood and decreased levels of these compounds in the urine.(6). During ketoacidosis, ketone bodies are excreted by the kidney, and during lactic acidosis, lactic acid is excreted.(7). Elevated blood glucose levels (over 180 mg/dL) in DM results in the excretion of glucose in the urine.Muscles, particularly those with a preponderance of white fibers, use their glycogen stores when exercising. Weight training is an anaerobic activity, and the muscles will degrade their own glycogen stores to provide glucose for energy. Blood glucose will not become available until the AMP levels increase significantly in the muscle.When Blood Sugar Increases:When Blood Sugar Decreases:Insulin is released, which leads to the dephosphorylation of:Glucagon is released, which leads to the phosphorylation of:PFK-2 (kinase activity now active)PFK-2 (phosphatase activity now active)Pyruvate kinase (now active)Pyruvate kinase (now inactive)Glycogen synthase (now active)Glycogen synthase (now inactive)Phosphorylase kinase (now inactive)Phosphorylase kinase (now active)Glycogen phosphorylase (now inactive)Glycogen phosphorylase (now active)Pyruvate dehydrogenase (now active)Pyruvate dehydrogenase (now inactive)Acetyl-CoA carboxylase (now active)Acetyl-CoA carboxylase (now inactive)Which leads to activeGlycolysis GlycogenolysisFatty acid synthesisFatty acid oxidationGlycogen synthesisGluconeogenesis Liver Enzymes Regulated by Activation/InhibitionEnzymeActivated byState in Which ActivePhosphofructokinase 1Fructose 2,6-bisP, AMPFedPyruvate carboxylaseAcetyl-CoAFed and fastingAcetyl-CoA carboxylaseCitrateFedCarnitine palmitoyltransferase ILoss of inhibitor (malonyl-CoA)FastingLiver Enzymes Regulated by Phosphorylation/DephosphorylationEnzymeActive formState in Which ActiveGlycogen synthaseDephosphorylatedFedPhosphorylase kinasePhosphorylatedFastingGlycogen phosphorylasePhosphorylatedFastingPhosphofructokinase- 2/fructose 2,6-bisphosphatase (acts as a kinase, increasing fructose2,6-bisP levels)DephosphorylatedFedPhosphofructokinase-2/fructose 2,6-bisphosphatase (acts as aphosphatase, decreasing fructose 2,6-bisP levels)PhosphorylatedFastingPyruvate kinaseDephosphorylatedFedPyruvate dehydrogenaseDephosphorylatedFed


Question: Transition mutation of GATCCT is

Point mutation is of 2 types:-

Transition Purine base is replaced by another purine base or pyrimidine base is replaced by another pyrimidine base.
Transversion Purine base is replaced by pyrimidine base or vice vessa.

In given question,
   GATCCT and GGTCCT  → only option A shows transition mutation


Question: Tangier disease is characterized by

DyslipoproteinemiasDefectRemarksFamilial alpha-lipoprotein deficiencyTangier diseaseFish-eye diseaseApo-A-I deficienciesAll have a low or near absence of HDLA tendency toward hyperiacylglycerolemia as a resultof the absence of apo C-ll, causing inactive LPL. Low LDLlevels. Atherosclerosis in the elderlyRef: Harper&;s biochemistry; 30th edition; Chapter 26; Cholesterol Synthesis, Transpo, & Excretion


Question: Glyconeogenesis is

Glyconeogenesis Synthesis of glycogen from non-carbohydrate precursors This pathway is the same as gluconeogenesis, but the last step is different i.e. In glyconeogenesis, glucose-6-Phosphate directly enters glycogen synthesis. So glucose-6-phosphatase step is not required. Glycogenesis -Synthesis of glycogen from glucose. Glycogenolysis- Breakdown of glycogen to produce glucose. Gluconeogenesis- Synthesis of glucose from non-carbohydrate precursors.

Synthesis of glucose from non-carbohydrate sources

Synthesis of glycogen from non-carbohydrate sources


Question: Essential pentosuria can occur due to deficiency in metabolic pathway of

Ans. a (Uronic acid) (Ref. Harper's Biochemistry-26th/pg. 105, 163, 170; 27th/pg. 177)Glucuronic acid is synthesized from glucose via the uronic acid pathway, of major significance for the excretion of metabolites and foreign chemicals (xenobiotics) as glucuronides. A deficiency in the pathway leads to essential pentosuria. Considerable quantities of L-xylulose appear in the urine because of absence of the enzyme necessary to reduce L-xylulose to xylitol. Parenteral administration of xylitol may lead to oxalosis, involving calcium oxalate deposition in brain and kidneys.URONIC ACID PATHWAY# In liver, uronic acid pathway catalyzes conversion of glucose to glucuronic acid, ascorbic acid, & pentoses.# It is also an alternative oxidative pathway for glucose, but--like the pentose phosphate pathway--it does not lead to the generation of ATP.# Glucose 6-phosphate is isomerized to glucose 1-phosphate, which then reacts with uridine triphosphate (UTP) to form uridine diphosphate glucose (UDPGlc) in a reaction catalyzed by UDPGlc pyrophosphorylase, as occurs in glycogen synthesis. UDPGlc is oxidized at carbon 6 by NAD-dependent UDPGlc dehydrogenase in a two-step reaction to yield UDP-glucuronate.Deficiencies in the enzymes of fructose and galactose metabolism lead to essential fructosuria and the galactosemias.


Question: The two strands of DNA are held together by

Two strands of DNA are held together by hydrogen bonds between complementary pairs of bases.


Question: In humans, telomeres have the following sequence

The ends of each chromosome contain structures called telomeres. Telomeres consist of sho TG-rich repeats. Human telomeres have a variable number of repeats of the sequence 5'-TTAGGG-3', which can extend for several kilobases. Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 531


Question: Heparin helps in the release of the enzyme

The repeating disaccharide heparin contains glucosamine (GlcN) and either of the two uronic acids (Figure 50-11). Most of the amino groups of the GlcN residues are N-sulfated, but a few are acetylated. The GlcN also carries a sulfate attached to carbon 6.Heparin is found in the granules of mast cells and also in liver, lung, and skin.It is an impoant anticoagulant. It binds with factors IX and XI, but its most impoant interaction is with plasma antithrombin(discussed in Chapter 55).Heparin can also bind specifically to lipoprotein lipase present in capillary walls, causing a release of this enzyme into the circulation.Reference: Harper biochemistry, 30th edition, page no 637


Question: Alkaline phosphatase contains

ALP is a nonspecific enzyme which hydrolyzes aliphatic, aromatic or heterocyclic compounds. the pH optimum for the enzyme reaction is between 9 and 10.it is activated by magnesium and manganese. zinc is a constituent ion of ALP.Ref: DM Vasudevan Biochemistry, page no: 305


Question: The primary role of chaperones is to help in

Proteins must fold to achieve their functional form. Folding can be spontaneous or facilitated by chaperones. Proteins that are defective (for example misfolded) or destined for rapid turnover are marked for destruction by the attachment of chains of a small, highly conserved protein called ubiquitin. Ubiquitinated proteins are rapidly degraded by a cytosolic complex known as the proteasome. Reference: Lippincotts illustrated reviews of Biochemistry Sixth edition: page no; 807


Question: Bone affection in scurvy is due to

Major consequences of vitamin C deficiency caused by impaired forma on of collagen. Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 414

Poor mineralization of the osteoid tissue


Question: The protein synthesis is sorted out at / by

(Golgi - Apparatus) (7 RS 7th)Golgi - complex (or Golgi - apparatus) or Dietysomes - Recent evidence suggests strongly that the complex serve as unique sorting device that recieve newly synthesized proteins* The post translational modifications takes place in the golgi lumen (median part) where the carbohydrate and lipid precursors are added to proteins to form glycoproteins and lipo proteins respectively* Ribosomes - are the centre of factories of protein synthesis* Rough Endoplasmic reticulum (RER) synthesizes membrane lipids and secretory proteins**


Question: Endoplasmic reticulum do not paicipate in

Rough Endoplasmic Reticulum is involved in protein synthesis. EPR also involved in glycosylation of N linked glycoproteins. Exocytic pathway of protein soing is done by both RER & GA (Golgi apparatus) Reference: Harper; 30th edition


Question: A deficiency of substance Folate can result in an anemia. Choose the type of anemia that would occur if the substance were deficient.

a. The 1-carbon groups that FH4 receives are transferred to various compounds (see Figure I below, steps 5 to 8).(1). Purine precursors obtain carbons 2 and 8 from FH4 . Purines are required for DNA and RNA synthesis.(2). dUMP forms dTMP by accepting a 1-carbon group from FH4 (Figure II). This reaction produces the thymine required for DNA synthesis.(a). The methylene group is reduced to a methyl group in this reaction, and FH4 is oxidized to FH2 .(b). FH2 is reduced to FH4 in the NADPH-requiring reaction catalyzed by FH2 reductase.(3). Glycine obtains a 1-carbon group from FH4 to form serine.(4). Vitamin B12 obtains a methyl group from 5-methyl-FH4 . The methyl group is transferred from methyl-B12 to homocysteine to form methionine (see Figure III, reaction 8). This is the only fate of 5-methyl-FH4 .Folate deficiency results in a megaloblastic anemia because of decreased production of purines and the pyrimidine thymine. Thus, lack of folate causes decreased DNA synthesis. In contrast with a vitamin B12 deficiency, neurologic problems do not occur in a folate deficiency. A hypochromic, microcytic anemia can result from the lack of iron, or lack of pyridoxal phosphate. Both conditions lead to a reduction in the synthesis of heme, so the red cells cannot carry as much oxygen (which gives them the pale color). The cells are small in order to maximize the concentration of hemoglobin present in the cells. Hemolytic anemia occurs when the red cell membrane fragments, which can occur with pyruvate kinase deficiencies or a lack of glucose-6-phosphate dehydrogenase activity (which results in reduced NADPH levels). Sickle cell anemia is caused by a point mutation in the b-globin gene, substituting a valine for a glutamic acid.I. The sources of carbon (1 to 4) for the FH4 pool and the recipients of carbon (5 to 8) from the pool. ATP, adenosine triphosphate; dUMP, deoxyuridine monophosphate; dTMP, deoxythymidine monophosphate; FH2 , dihydrofolate; FH4 , tetrahydrofolate; NAD, nicotinamide adenine dinucleotide; NADP, nicotinamide adenine dinucleotide phosphate; NADPH, reduced NADP; Pi, inorganic phosphate; PPi, pyrophosphate.II. The transfer of a 1-carbon unit from serine to deoxyuridine monophosphate (dUMP) to form deoxythymidine monophosphate (dTMP). FH4 is oxidized to FH2 in this reaction. FH2 is reduced to FH4 by dihydrofolate reductase. The rectangles indicate the steps at which the antimetabolites methotrexate and 5-fluorouracil act. FH2 , dihydrofolate; FH4 , tetrahydrofolate; NADP, nicotinamide adenine dinucleotide phosphate; NADPH, reduced NADP.III. The decarboxylation of glutamate to form GABA. PLP, pyridoxal phosphate. GABA, g-aminobutyric acid.


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

Farber disease (also known as Farber&;s lipogranulomatosis, ceramidase deficiency, "Fibrocytic dysmucopolysaccharidosis," and "Lipogranulomatosis" is an extremely rare autosomal recessive lysosomal storage disease marked by a deficiency in the enzyme ceramidase that causes an accumulation of fatty material sphingolipids leading to abnormalities in the joints, liver, throat, tissues and central nervous system. Normally, the enzyme ceramidase breaks down fatty material in the body's cells. In Farber Disease, the gene responsible for making this enzyme is mutated. Hence, the fatty material is never broken down and, instead, accumulates in various pas of the body,


Question: Beta alanine is formed from

Beta alanine is formed from cytosine and Uracil.


Question: Gluconeogenesis enzyme stimulated in starvation

In starvation, there is excessive breakdown of fatty acids resulting in the formation of Acetyl CoA in the liver. They ensure the conversion of pyruvate to oxaloacetic acid. It acts as allosteric activator of the enzyme pyruvate carboxylase and inhibits pyruvate dehydrogenase of Glycolysis.


Question: Rate limiting enzyme in cholesterol synthesis


Question: Essential fatty acids

ESSENTIAL FATTY ACIDSThree polyunsaturated fatty acids, linoleic acid, linolenic acid and arachidonic acid are called "essential fatty acids" (EFA). They cannot be synthesised in the body andmust be provided in the diet. Lack of EFA in the diet can produce growth retardation and other deficiency manifestation symptoms.Which EFA is Impoant?Linoleic acid is most impoant as, arachidonic acid can be synthesised from linoleic acid by a three-stage reaction by addition of acetyl-CoA. Pyridoxal phosphate is necessary for this conversion. Biologically arachidonic acid is very impoant as it is precursor from which prostaglandins and leukotrienes are synthesised in the body.Why EFA cannot be Synthesised?Introduction of additional double bonds in unsaturated fatty acid is limited to the area between - COOH group and the existing double bond and that it is not possible to introduce a double bond between the - CH3 group at the opposite end of the molecule and the first unsaturated linkage. This would explain body's inability to synthesise an EFA from oleic acid.Functions of EFA: (Biomedical Impoance)Structural elements of tissues: Polyunsaturated fatty acids occur in higher concentration in lipids associated with structural elements of tissues.Structural element of gonads: Lipids of gonads also contain a high concentration of polyunsaturated fatty acids, which suggests impoance of these compounds in reproductive function.Synthesis of prostaglandins and other compounds: Prostaglandins are synthesised from Arachidonic acid by cyclooxygenase enzyme system. Leucotrienes are conjugated trienes formed from arachidonic acid in leucocytes by the Lipoxygenase pathway.Structural element of mitochondrial membrane: A deficiency of EFA causes swelling of mitochondrial membrane and reduction in efficiency of oxidative phosphorylation. This may explain for increased heat production noted in EFA deficient animals.Serum level of cholesterol: Fats with high content of polyunsaturated fatty acids tends to lower serum level of cholesterol.Effect on clotting time: Prolongation of clotting time is noted in ingestion of fats rich in EFA.Effect on fibrinolytic activity: An increase in fibrinolytic activity follows the ingestion of fats rich in EFA.Role of EFA in fatty liver: Deficiency of EFA produces fatty liver.Role in vision: Docosahexaenoic acid (22:6n-3) is the most abundant polyenoic fatty acids present in retinal photoreceptor membranes. Docosahexaenoic acid is formed from dietary linolenic acid. It enhances the electrical response of the photoreceptors to illumination. Hence linolenic acid is necessary in the diet for optimal vision.Deficiency manifestations: A deficiency of EFA has not yet been unequivocally demonstrated in humans. In weaning animals, symptoms of EFA deficiency are readily produced. They are Cessation of growth.Skin lesions: Acanthosis (hyperophy of prickle cells) and hyperkeratosis (hyperophy of stratum corneum). Skin becomes abnormally permeable to water. Increased loss of water increases BMR.Abnormalities of pregnancy and lactation in adult females.Fatty liver accompanied by increased rates of fatty acids synthesis lessened resistance to stress.Kidney damage.CLINICAL ASPECTHuman deficiency: Some cases ofEczema like dermatitis,Degenerative changes in aerial wall andFatty liver in man may be due to EFA deficiency.There are also some repos that administration of EFA in such cases may produce:Some improvement of eczema in children kept on skimmed milk,Prevent fatty liver (some cases) andLowering of cholesterol levels.Infants and babies with low-fat diet develop typical skin lesions which have shown to be improved with EFA (linoleic acid).Fate of EFA: EFA undergoes b-oxidation after necessary isomerisation and epimerisation, like other unsaturated fatty acids.CLINICAL ASPECTAbnormal Metabolism of EFAAbnormal metabolism of EFA, which may be concerned with dietary insufficiency, has been noted in a number of disease like cystic fibrosis, hepatorenal syndrome, Crohn's disease, acrodermatitis enteropathica, Sjogren's syndrome, Cirrhosis and Reye's syndrome.Ref: M.N. Chatterjee - Textbook of Biochemistry, 8th edition, page no: 48-49


Question: Malonate competetively inhibits


Question: Investigation of choice in Thiamine deficiency is

Severe thiamine deficiency is associated with: Decreased RBC transketolase activity this is the earliest manifestation seen even before clinical disturbances Thiamin is a cofactor of Transketolase pyruvate, alpha-ketoglutarate and lactate level in blood increases in thiamine deficiency ref: DM Vasudevan 8th ed page 467


Question: Function of Endonucleases

(D) Cut DNA at specific DNA sequences # Restriction enzymes(endonucleases) are bacterial proteins that recognize specific DNA sequences and cut DNA at or near the recognition site. These enzymes are widely used in molecular genetics for analyzing DNA and creating recombinant DNA molecules. The ability of restriction enzymes to reproducibly cut DNA at specific sequences has led to the widespread use of these tools in many molecular genetics techniques. Restriction enzymes can be used to map DNA fragments or genomes. Mapping means determining the order of the restriction enzyme sites in the genome. These maps form a foundation for much other genetic analysis. Restriction enzymes are also frequently used to verify the identity of a specific DNA fragment, based on the known restriction enzyme sites that it contains.


Question: In muscle, Phosphorylase a is inactivated by

In the liver, the role of glycogen is to provide free glucose for export to maintain the blood concentration of glucose.
In muscle the role of glycogen is to provide a source of glucose-6-phosphate for glycolysis in response to the need for ATP for muscle contraction.
In both tissues, the enzyme is activated by phosphorylation catalyzed by phosphorylase kinase (to yield phosphorylase a) and inactivated by dephosphorylation catalyzed by phosphoprotein phosphatase (to yield phosphorylase b), in response to hormonal and other signals.
There is instantaneous overriding of this hormonal control. Active phosphorylase a in both tissues is allosterically inhibited by ATP and glucose-6-phosphate; in liver, but not muscle, free glucose is also an inhibitor.

Harper 30th edition page 179


Question: Von Gierke disease enzyme deficient


Question: The best technique to isolate DNA from enamel and dentin is


Question: Magnesium

It is uncommon and always due to excessive intake either orally (antacids), rectally (enema) or parenterally. Causes of hypermagnesemia are listed in Box 35.19. Magnesium intoxication causes depression of neuromuscular system, causing lethargy, hypotension, respiratory depression, brady- cardia and weak tendon reflexes. In severe conditions, acute rhabdomyolysis results. Hypermagnesemia induces decrease in serum calcium by inhibiting PTH secretion, which in turn will have deleterious effects.Ref: DM Vasudevan, page no: 412

Is essential for efficient secretion and peripheral action of PTH

Is essential for efficient secretion and peripheral action of calcitonin

Competitively occupies calcium slots in bone


Question: Renal threshold for glycosuria

For glucose, the renal threshold is 180 mg/dl and Tm is 375 mg/min. In other words, glucose stas to appear in urine when blood level is more than 180 mg/dl, and all the glucose molecules above 375 mg are excreted in the urine. abnormal conditions, the renal threshold may be lowered so that even at lower blood levels, compounds are excreted in urine, e.g. renal glycosuria (glucose); and renal tubular acidosis (bicarbonate).Ref: DM Vasudevan, 7th edition, page no: 316


Question: Carbamoyl phosphate intermediates the synthesis of

(B) Urea & Pyrimidine # Biosynthesis of urea begins with the condensation of CC>2, NHs and ATP to form carbamoyl phosphate, a reaction catalyzed by carbamoyl phosphate synthase I which is a mitochondrial enzyme, and rate limiting or pacemaker enzyme and the enzyme is active only in the presence of its allosteric activator N-acetylglutamate, which enhances the affinity of synthase for ATP.


Question: Most abundant type of collagen in human body

The major structural protein found in connective tissue is the collagen..It is the most abundant protein found in body. Type I is the most abundant forn , seen in connective tissues in almost all regions of the body. Type II is mainly seen in cailage and vitreous humor. Type III is seen in skin, lung and vascular tissues and Typa IV is seen in the basement membranes. THE COLLAGEN IS SYNTHESIZED BY FIBROBLASTS INTRACELLULARLY,AS A LARGE PRECURSOR,CALLED PROCOLLAGEN.iT IS THEN SECRETED. REFERENCE: DM VASUDEVAN TEXTBOOK SEVENTH EDITION ; PAGE NO :720


Question: Nephelometry is based on the principle of

Light attenuated in intensity by scattering [Ref: nephelonzetyy and turbidimetry methods are based on the phenomenon whereby light, passing through a medium with dispersed paicles of a different refractive index from that of the medium, is attenuated in intensity by scattering.In turbidimetry, the intensity of light transmitted through the medium, the unscattered light, is measured.In nephelometry, the intensity of the scattered light is measured, usually, but not necessarily, at right angles to the incident light beam.The intensity of the scattered radiation depends on several factors, including the wavelength of the incident radiation and the paicle size; however, in a given system, the scattering is directly propoional to the concentration of the paiculate matter.


Question: Amino acid required for formation of thyroxine

Metabolic role of Tyrosine * Synthesis of thyroid hormones: Thyroxine (T4) and triiodothyronine (T3) * Synthesis of catecholamines * Synthesis of melanin pigment * Formation of tyramine * Formation of phenol and cresol * Formation of tyrosine-O-sulphateRef: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 497


Question: Leucine zipper complex is

Proteins that bind to DNA contain a limited number of motifs.The helix-loop-helix motif is an example found in a number of proteins that function in a number of proteins that function as transcription factors Example: zinc fingers, and leucine zippers . REF :LIPPINCOTT'S TEXTBOOK OF BICHEMISTRY ;8th EDITION ;Page no :18 AND 422.


Question: Serum enzyme used for MI

The enzymes routinely measured in the clinical laboratory for the purpose of diagnosing and monitoring myocardial infarction include creatine kinase (CK), aspaate aminotransferase (sGOT or AST), and lactate dehydrogenase (LDH).


Question: Phenylbutyrate is used in urea cycle disorders because it

In all urea cycle disorders there is accumulation of NH3 (hyperammonemia) which is very toxic and has to be removed Using scavenging agents:- One of the treatment of urea cycle disorder is the use of NH3 scavenging agents These are Phenylbutyrate and Sodium benzoate Phenyl butyrate reacts with glutamine to get conveed in to phenyl acetyl glutamine which can be excreted. Other method to treat urea cycle disorders: Give Arginine (1st line Treatment ) An essential amino acid Provides ornithine (required in 2nd step of urea cycle) Activator of NAGS But it is contraindicated in Arginase deficiency Restrict protein intake to 50% of normal


Question: Pellagra is caused by the deficiency of


Question: Lesh Nyhan syndrome is associated with deficiency of

REF :DM VASUDEVAN TEXTBOOK :7th EDITION ;Page no :403 Disease deficient enzyme GPD Deficiency G6PD Gaucher's disease beta glucosidase Lesch-Nyhan syndrome HGPase


Question: The human plasma lipoprotein containing the highest percentage of triacylglycerol by weight is

CHYLOMICRONS Synthesis of chylomicrons Chylomicrons are formed in the intestinal mucosal cells, and secreted into the lacteals of lymphatic system (Chapter 11). They are rich in triglyceride (Fig. 12.9). If lipemic serum is kept overnight in the refrigerator, chylomicrons rise as a creamy layer to the top, leaving the subnatant clear. When the chylomicrons are synthesised by the intestinal mucosa, they contain only apo-B-48 and apo-A but apo-C and apo-E are added from HDL in blood during transpo (Fig. 12.10). Metabolism of Chylomicrons i. Main sites of metabolism of chylomicrons are adipose tissue and skeletal muscle. The half-life of chylomicrons in blood is about 1 hour. ii. The enzyme lipoprotein lipase (LpL) is located at the endothelial layer of capillaries of adipose tissue, muscles, and hea; but not in liver. Apo C-II present in the chylomicrons activates the LpL (Table 12.4). The LpL hydrolyses triglycerides present in chylomicrons into fatty acids and glycerol. Muscle or adipose tissue cells take up the liberated fatty acids (Fig. 12.10). iii. Following injection of heparin, the LpL is released from the tissues and lipemia is thus cleared. This is called post-heparin lipolytic activity. Lack of C-II leads to decreased activity of LpL and consequent accumulation of chylomicrons and VLDL in blood. Insulin increases LpL activity. Liver Takes up Chylomicron Remnants As the TAG content is progressively decreased, the chylomicrons shrink in size. These remnants containing apo-B-48 and apo-E are taken up by hepatic cells by receptor-mediated endocytosis. Apo-E binds the hepatic receptors (Fig. 12.10). Function of Chylomicrons Chylomicrons are the transpo form of dietary triglycerides from intestines to the adipose tissue for storage, and to muscle or hea for their energy needs.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 153


Question: Adenylate cyclase conves

Adenylate cyclase (calmodulin-sensitive) trimer, Bacillus anthracis Epinephrine binds its receptor, that associates with a heterotrimeric G protein. The G protein associates with adenylyl cyclase, which conves ATP to cAMP, spreading the signs


Question: Not seen in hypervitaminosis

Hypervitaminosis A causes Acute toxicity: Pseudotumor cerebri (raised intracranial tension) (headache, dizziness, vomiting, stupor, and blurred vision, symptoms that may be confused with a brain tumour) loss of hair (alopecia), Weight loss, anorexia, nausea, vomiting, bony exostosis, bone and joint pain, decreased cognition, hepatomegaly progresses to cirrhosis hypervitaminosis D causes weakness, polyuria, intense thirst, hypeension, weight loss. ref DM Vasudevan 8th ed page 457, 460


Question: DNA proof reading and repair is done by

DNA Polymerases Ecoli Eukaryotic Function I Gap filling following DNA replication, repair, and recombination II DNA proofreading and repair b DNA repair g Mitochondrial DNA synthesis III e Processive, leading strand synthesis a Primase d Processive, lagging strand synthesis Harper30e pg: 383


Question: Peroxidase enzyme is used in estimating

The blood glucose analysis is ordered to measure the amount of blood at the time of sample collection. It is used to detect both hyperglycemia and hypoglycemia and helping the diagnosis of diabetes. An ideal blood glucose estimation method should determine only glucose. It is adaptable for both macro- and semi-micro- techniques. Reagents are relatively inexpensive and the method should require a minimum of time, techniques and apparatus, be accurate and yield reproducible results. Glucose oxidase(peroxidase) is an enzyme highly specific for glucose and is not react with blood saccharides. So it has been employed for the estimation of blood glucose.


Question: Enzyme deficiency in Acute intermittent porphyria is

B. i.e. (Uroporphyrinogen- I synthase) (286 - Harper 27th)Enzyme involvedPorphyria* ALA synthase* Uroporphyrinogen I synthase- X- linked sideroblastic anemia- Acute Intermittent porphyria* Uroporphyrinogen III synthase- Congenital erythropoietic porphyria* Uroporphyrinogen decarboxylase- Porphyria cutanea tarda* ALA synthase is the rate controlling step in hepatic porphyrin biosynthesis*** Porphyrins are synthesized mainly in Liver and bone marrow*** The conversion of uroporphyrinogen III to coproporphyrinogen III is an example of - Decarboxylation*** Prophobilinogen in urine produces pink colour with Ehrlich's aldehyde reagent**


Question: An Immunoglobulin molecule represents the following level of organized protein structure

A complete immunoglobulin molecule represents Ouanternary level of organization between four polypeptide chains (two light chains and two heavy chains). It has a heterotetrameric quaternary structure.


Question: Cholesterol is a(an)

Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 146


Question: Amino acid cannot used for glycogen synthesis


Question: Iron is absorbed in

You should know the site of absorption of the following:


Question: Urea synthesis is mediated by

Arginase catalyses the formation of urea from arginine.


Question: Boiled cabbage or rancid butter smelling urine is seen in Phenylketonuria

REF: Lippincott book of biochemistry 6th ed. Tyrosinaemia is an error of metabolism, inherited, in which the body cannot effectively break down the amino acid tyrosine, found in most animal and plant proteins. It is an autosomal recessive, which means two copies of an abnormal gene must be present in order for this to develop. There are three types of tyrosinemia, each with distinctive symptoms and caused by the deficiency of a different enzyme. One of the symptoms of Tyrodinaemia type 1 is an odor like cabbage or rancid butter.


Question: Azathioprine is used as

CompoundUseNucleoside analogueBromodeoxyuridineaStudy cell proliferationThymidine analogueAllopurinalAnti gout drugHypoxanthine analogueAzathiopineImmunosuppressantPurine analogue


Question: Myocardial infarction is associated with increased of

C. i.e. (CPK - MB) (III - U. Satyanarayan 3rd) (599- Rana Shinde 7th)CPK exists as three isoenzyme - Each isoenzyme is a dimmer composed of two subunits - M (muscle) or B (brain) or bothIso enzymeSubunitTissue of originCPK,BBBraincpk2MBHeartCPK3MMSkeletal muscle* CPK2- MB is the earliest reliable indication of myocardial infarction* Troponins are more sensitive and specific*** CPK - NOT found in RB cells and it level is not affected by haemolysis* Normal value - 4 - 60 IU/L (at 37degC)


Question: Chymotrypsinogen is a

Ans. is 'a' i.e. Zymogen * Proteolytic digestive enzymes known as proteases have two main classes depending on specificity for the amino acids forming the peptide bond to be hydrolysed.


Question: Agranular cytoplasmic reticulum is involved in the synthesis of

Ans. is 'b' i.e. lipid [Ref: Guyton 11/e, p 20, 21; Chatterjee Shinde 6/e, p 6, 71There are two kinds of endoplasmic reticulum :Rough or granular ER or ergastoplasmThey are coated with ribosomesFunction of rough ERprotein synthesisSmooth or agranular ERThey do not have attached ribosomesFunctions of smooth ERlipid synthesismodification and transport of protein synthesized in rough ERprovides the enzymes that control glycogen breakdown when glycogen is to be used for energyprovides a vast number of enzymes that are capable of detoxifying substances, such as drugs, that might damage the cell

Miscellaneous (Structure & Function of Proteins)


Question: Taysach's disease is due to the deficiency of

(A) Hexosaminidase # Tay-Sachs disease (TSD, GM2 gangliosidosis, Hexosaminidase A deficiency or Sphingolipidosis) is a genetic disorder, fatal in its most common variant known as Infantile Tay-Sachs disease. TSD is inherited in an autosomal recessive pattern.> Disease occurs when harmful quantities of a fatty acid derivative called a ganglioside accumulate in the nerve cells of the brain.> Gangliosides are lipids, components of cellular membranes, and the ganglioside GM2, implicated in Tay-Sachs disease, is especially common in the nervous tissue of the brain.


Question: Number of ATP molecules and NADH formed in each cycle of glycolysis

Glycolysis Site of occurrence Cytosol Aerobic glycolysis Glucose - Pyruvate ; 8 ATP Anaerobic glycolysis Glucose - Lactate ; 2 ATPReaction occurring in aerobic conditions only Glyceraldehyde 3 phosphate - 1,3- bisphosphoglycerate Inhibitors Glyceraldehyde 3 phosphateIodo acetate 1,3 bisphosphoglycerate Arsenite Enolase Fluoride Glycolysis TCA cycle Malate shuttle ( Liver , Hea , Kidney )38 ATP / 32 ATP ( new )Glycolysis TCA cycle Glycerophosphate shuttle ( Brain , White skeletal muscles )36 ATP / 30 ATP ( new )Irreversible reactions Reactions Enzymes Glucose - Glucose-6-phosphateHexokinase Fructose-6-phosphate - Fructose-1,6,bisphosphatePhosphofructokinasePhosphoenolpyruvate - Pyruvate Pyruvate kinase Oxidative / Substrate level phosphorylation Reactions Enzymes 1,3- bisphosphoglycerate - 3 phosphoglyceratePhosphoglycerate kinase Phosphoenol pyruvate - Pyruvate Pyruvate kinase DM Vasudevan , Textbook of Biochemistry for Medical Students , 7th ed, page 108


Question: The genetic defect in Refsum's disease lies in


Question: Zinc is a cofactor for

More than 300 enzymes are zinc-dependent. Some impoant ones are carboxypeptidase, carbonic anhydrase, alkaline phosphatase, lactate dehydrogenase, alcoholdehydrogenase and glutamate dehydrogenase. RNA polymerase contains zinc and so it is required for protein biosynthesis. Extracellular superoxide dismutase is zinc-dependentand so, zinc has antioxidant activity.Alternatively, all-trans-retinal is transpoed to liver and then reduced to all-trans-retinol by alcohol dehydrogenase (ADH), an NADH dependent enzyme. ADH contains zinc, and therefore, zinc is impoant in retinol metabolism. The all-trans-retinol is isomerized to 11-cis-retinol and then oxidized to 11-cis-retinal in the liver. This is then transpoed to the retina. This completes the Wald&;s visual cycleRef: DM Vasudevan, Page no: 429


Question: Apolipoprotein E is rich in

TYPES OF APOPROTEINS PRESENT IN VARIOUS LIPOPROTEIN FRACTIONS (CHEMISTRY OF APOPROTEINS)HDL: Two major apoproteins of HDL are designated as apo-A-I and apo-A-II. In addition to the above, HDL also contains apo-C-I, C-II, and C-III. HDL-3 is characterised by having apo-D and HDL may also acquire arginine-rich apo-E.LDL: The main apoprotein of LDL is apo-B100, which is also present in VLDL.Chylomicrons: Principal apoprotein of chylomicrons is apo-B48 (Mol.wt = 200 Kd). In addition, chylomicrons also contain apo-A (AI and AII) and apo-C (C-II and C-III), also arginine-rich apo-E (34 Kd). Apo- C seems to be freely transferable between chylomicrons and VLDL on one hand and HDL on the other.VLDL and LDL: Principal apoproteins of VLDL, IDL, and LDL is apo-B100 (350 Kd). They also contain apo-C (C-I, C-II, and C-III), and apo-E. IDL carries some apo-E apoprotein. Apo-E: Arginine-rich apo-E, isolated from VLDL. It contains arginine to the extent of 10 percent of the total amino acids and accounts for 5 to 10 percent of total VLDL apo-proteins in normal subjects but is present in excess in the "broad" b-VLDL of patients of type III hyperlipoproteinemia. Carbohydrate content: Carbohydrates account for approx. 5 percent Apo-B and include mannose, galactose, fucose, glucose, glucosamine and sialic acid. So, some of the lipoproteins are glycoproteins.Ref: Textbook of Medical Biochemistry 8th Edition Dr (Brig) MN Chatterjea, Rana Shinde page no: 445


Question: Gamma carboxylation of glutamic acid in clotting factor II, VII and protein C is dependent on


Question: Ammonia in brain is trapped by

Ans. is 'b' i.e.,Glutamine The brain is a rich source of glutamine synthase and predominantly detoxifies ammonia by synthesis of glutamine.Glutamate + NH4 - Glutamine sythetase - Glutamine


Question: Formation of DNA using RNA template is done by

There exists in one species of animal viruses (retroviruses) a class of enzymes capable of synthesizing a single-stranded and then a dsDNA molecule from a single-stranded RNA template. This polymerase termed RNA-dependent DNA polymerase, or "reverse transcriptase," first synthesizes a DNA-RNA hybrid molecule utilizing the RNA genome as a template. A specific virus-encoded nuclease, RNase H, degrades the hybridized template RNA strand, and the remaining DNA strand, in turn, serves as a template to form a dsDNA molecule containing the information originally present in the RNA genome of the animal virus.Ref: Harpers Illustrated Biochemistry, 30th edition, page no: 387


Question: Malonate is a competitive inhibitor of

Barbiturates such as amobarbital inhibit electron transpo Complex I by blocking the transfer from Fe-S to Q. At sufficient dosage, they are fatal in vivo. Antimycin A and dimercaprol inhibit the respiratory chain at Complex III. The classic poisons H2S, carbon monoxide, and cyanide inhibit Complex IV and can therefore totally arrest respiration. Malonate is a competitive inhibitor of Complex II Reference: Harper; 30th edition; Page no: 132


Question: Not a dietary source of vit. B12


Question: Ketone bodies are not utilized by

Red blood cells lack mitochondria, and hence the enzymes of the TCA cycle, electron transpo chain, b-oxidation pathway, or ATP synthase. This renders them incapable of utilizing fatty acids or ketone bodies as metabolic fuel. Consequently, red blood cells are completely reliant on glycolysis to generate ATP. Glucose enters red blood cells by facilitated diffusion, a process mediated by the glucose transpoer (GLUT1), also known as glucose permease.Ref: Harper&;s biochemistry; 30th edition; Page no: 691


Question: Keratin of skin is softer than keratin in nail because keratin in skin has

Keratin in skin is softer than keratin in nail, horns because of lesser disulphide linkages between cysteine residues Ref: Biochemistry by U. Satyanarayana 3rd edition Pgno : 489


Question: The sequence that targets protein to lysosmoes

Mannose 6 - phosphate acts as a tag for the proteins to reach lysosomes. Defects in the process of tagging  this sequence to protein result in I - Cell disease.


Question: Tricarboxylic acid cycle to be continuous requires the regeneration of

Oxaloacetate may be viewed as a catalyst, which enters into the reaction, causes complete oxidation of acetyl CoA and comes out of it without any change.
Reference: Vasudevan 7th  ed, pg 249


Question: Signal peptides are synthesized in


Question: In Familial hypercholesterolemia there is


Question: Marquios disease not seen is

Morquio syndrome is an inherited disease of metabolism in which the body is missing or doesn&;t have enough of a substance needed to break down long chains of sugar molecules called glycosaminoglycans (formerly called mucopolysaccharides).SymptomsAbnormal development of bones, including the spineBell-shaped chest with ribs flared out at the bottomCoarse facial featuresKnock-kneesLarge head (<a href=" spaced teeth


Question: Uncoupler in ETC

Dinitrophenol (DNP) a potent uncoupler is amphipathic and increase the permeability of the lipoid inner mitochondrial membrane to protons (H+), thus reducing the electrochemical potential and sho-circuiting the ATP synthase. In this way, oxidation can proceed without phosphorylation.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 146


Question: Cholesterol is a predominant lipid in

LDL and HDL lipoproteins are the major carrier of cholesterol . Reference: Harpers illustrated biochemistry 31st edition page 248


Question: Maple syrup urine disease is due to

Maple syrup urine disease is also known as Branched chain ketonuria. The basic biochemical deformity is deficient decarboxylation of branched-chain keto acid. This is due to the deficiency of alpha-ketoacid decarboxylase.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 230