Question: Vit K is involved in


Question: During unwinding of DNA, relief of supercoil is made possible by

During unwinding of DNA, relief of supercoil is made possible by Topoisomerase DNA helicase unwinds the DNA without cutting but using energy from hydrolysis of ATP. Gyrase is a bacterial type II topoisomerase which acts on closed circular DNA (bacteria have circular DNA).


Question: Major metabolic fuel for hea in starvation is

The liver has a greater capacity for b-oxidation than is required to meet its own energy needs, and as fasting becomes more prolonged, it forms more acetyl-CoA than can be oxidized. This acetyl-CoA is used to synthesize the ketone bodies which are major metabolic fuels for skeletal and hea muscle and can meet up to 20% of the brain's energy needs. In prolonged starvation, glucose may represent less than 10% of whole body energy-yielding metabolism. Reference: Harper; 30th edition; Chapter 14; Page no: 148


Question: Pellagra symptoms are aggravated if diet contains

Pellagra symptoms are aggravated if diet contains high amount of leucine. Dietary deficiency of Tryptophan: Pellagra is seen among people whose staple diet is maize (South and Central America). In maize, niacin is present; but it is in a bound form, and is unavailable. Pellagra is also seen when staple diet is sorghum (jowar or guinea corn) as in Central and Western India. Sorghum contains leucine in high quantities. Leucine inhibits the QP enzyme, and so cannot be conveed to NAD+ (Leucine pellagra). Reference: Textbook of Biochemistry by D M Vasudevan, sixth edition pg no. 395, 396.


Question: Phenylalanine is degraded into

Phenylalanine is first conveed to tyrosine (For Subsequent metabolism of phenylalanine and tyrosine See att. Treasure. Hereditary tyrosinemia type I (Hepatorenal tyrosinemia) is due to deficiency of the enzyme fumaryl acetoacetate hydrolase (fumarylacetoacetase). Remember the enzyme deficiency - fumarylacetoacetase. That will help you to remember the end products - Fumarate and acetoacetate. Phenylalanine & tyrosine are both glucogenic and ketogenic. Fumarate is glucogenic while acetoacetate is ketogenic.

Phenylalanine and Tyrosine metabolism Detail


Question: Enzyme generating urea is

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


Question: The key regulatory enzyme in hepatic biosynthesis of heme is

ALA Synthase Is the Key Regulatory Enzyme in Hepatic Biosynthesis of HemeThere are two isozymes of ALA synthase. ALAS1 is expressed throughout the body; ALAS2 is expressed in erythrocyte precursor cells.The reaction catalyzed by ALA synthase 1 is rate-limiting for biosynthesis of heme in liver. It appears that heme, probably acting through an aporepressormolecule, acts as a negative regulator of the synthesis ofALAS1 The rate of synthesis of ALAS1 thus increases greatly in the absence of heme but diminishes in its presence.Heme also affects translation of the enzyme and its transfer from the cytosol to the mitochondrion. ALAS1 has a sho half-life, which is typical for an enzyme that catalyzes a rate-limiting reaction.Reference: Harper biochemistry, 30th edition, page no 326


Question: The adenylate cyclase system is mediated by

The cAMP-dependent pathway, also known as the adenylyl cyclase pathway, is a G protein-coupled receptor-triggered signaling cascade used in cell communication G protein-coupled receptors (GPCRs) are a large family of integral membrane proteins that respond to a variety of extracellular stimuli. Each GPCR binds to and is activated by a specific ligand stimulus that ranges in size from small molecule catecholamines, lipids, or neurotransmitters to large protein hormones. When a GPCR is activated by its extracellular ligand, a conformational change is induced in the receptor that is transmitted to an attached intracellular heterotrimeric G protein complex. The Gs alpha subunit of the stimulated G protein complex exchanges GDP for GTP and is released from the complex. In a cAMP-dependent pathway, the activated Gs alpha subunit binds to and activates an enzyme called adenylyl cyclase, which, in turn, catalyzes the conversion of ATP into cyclic adenosine monophosphate (cAMP). Increases in the concentration of the second messenger cAMP may lead to the activation of cyclic nucleotide-gated ion channels


Question: Most appropriate action of ubiquiting includes

Proteins are marked for degradation by the attachment of ubiquitin to the amino group of the side chain of a lysine residue. Additional ubiquitins are then added to form a multiubiquitin chain. Such polyubiquinatedproteins are recognized and degraded by a large, multisubunit protease complex, called the proteasome


Question: In RBC the enzyme deficient is

Pyruvate kinase is an enzyme that helps Cells turn sugar(glucose) into energy (Called Adenosine Triphsphate,ATP) in a process called glycolysis . Red cells rely on this process for energy and so, pyruvate kinase deficiency leads to a deficiency in energy and to premature red cell destruction .


Question: Not gluconeogenic

The major non-carbohydrate precursors of glucose are lactate, glucogenic amino acids (all except leucine) and glycerol. Lactate is formed by RBC in glycolysis because mitochondria are absent. Lactate is also formed by active skeletal muscle when the rate of glycolysis exceeds the rate of TCA cycle, the pyruvate formed is conveed to lactate.Ref: DM Vasudevan, 7th edition, page no: 117


Question: Cerebrosides consist mostly of this

Both glucocerebrosides and galacto cerebrosides are present however galactocerebrosides are most commonly seen on neural cells and are abundant


Question: UDP glucose is not used in

Glycogen Synthase - The glucose moiety from UDP-glucose is transferred to a glycogen primer (glycogenin) molecule. The primer is essential to accept the glycosyl unit. The primer is made up of a protein-carbohydrate complex. It is a dimeric protein, having two identical monomers. An oligosaccharide chain of 7 glucose units is added to each monomer. Glycogen primer (n)+ UDP-glucose --------- Glycogen (n+1) + UDP In the next step, activated glucose units are sequentially added by the enzyme glycogen synthase. The glucose unit is added to the nonreducing (outer) end of the glycogen primer to form an alpha-1,4 glycosidic linkage and UDP is liberated. GALACTOSE METABOLISM - Galactose is a constituent of lactose of milk sugar, and is taken in the diet. Galactose is not an essential nutrient, because UDP glucose can form UDP galactose. REF: DM VASUDEVAN TEXTBOOK OF BIOCHEMISTRY, SIXTH EDITION,PG.NO.,109,120.


Question: Polyamine Ike putrescine is derived from

The enzyme ornithine decarboxylase (ODC) catalyzes the decarboxylation of ornithine (a product of the urea cycle) to form putrescine. This reaction is the committed step in polyamine synthesis. In humans, this protein has 461 amino acids and forms a homodimer.Ref: https://en.wikipedia.org/wiki/Ornithine_decarboxylase


Question: Accumulation of sphingomyelin in phagocytic cells is feature of

Ans. is 'b' ie., Niemann pick disease First three options are types of Lysosomal storage disordersThe characteristic feature of lysosomal storage disorders is accumulation of specific macromolecules within cells that are normally metabolized by the cells. This is because of deficiency of one or other lysosomal enzymesSome important lysosomal storage disorders , the deficient enzymes and the stored macromolecule are listed below--Lysomal Storage DiseaseDeficient EnzymeStored Material* Fabry's ds*a- Galactosidase AGlobotriaosyl ceramide* Gaucher's ds*Acid beta - glucosidaseGlucosyl-ceramidase* Niemann - Pick ds*SphingomyelinaseSphingomyelin* Tay -Sach's ds*b - hexosaminidase AGM2 gangliosides* Sandhoff ds*b - hexosaminidase A and BGM2 gangliosides* Hurler's ds*a - L-iduronidaseDermatan sulfate Heparan sulfate* Hunter's ds*Iduronate sulfataseDermatan sulfate* Metachromatic leukodystrophy*Arylsulfatase -ACerebroside - sulfate* Krabbe's ds*GalactosylceramidaseGalactosylceramide Galactosyl sphingosine

Phospholipids, Glycolipids and their disorders


Question: A Protein estimation test is confused with

On heating the urine, turbidity arises if proteins are present.
However, turbidity also arises if phosphates or carbonates are present in urine. This can leads to confusion.
Addition of few drops of acetic acid dissolves the turbidity due to phosphates or carbonates, whereas turbidity due to proteins remains persistent.


Question: Rough endoplasmic reticulum is site of synthesis for

Ans. is 'a' i.e. Protein Rough endoplasmic reticulum is concerned withProtein synthesis*Initial folding of the polypeptide chains with the formation of disulfide bondsSmooth endoplasmic reticulum is concerned withSteroid synthesis*Detoxification processesAs sarcoplasmic reticulum plays important role in skeletal and cardiac muscle contraction *


Question: The cellular component for protein synthesis is

Although both ribosomes & RER are involved in the synthesis of protein, the cellular component on which all interactions take place to synthesize the protein in the ribosome.


Question: Thermogenin is present in

Thermogenin, a protein present in the inner mitochondrial membrane of adipocytes, provides an alternate pathway for protons. It is one of the uncoupling proteins (UCP).Ref: DM Vasudevan Textbook of Medical Biochemistry, 6th edition, page no: 234


Question: Hurler syndrome is due to deficiency of

Heparitin Sulphate Isolated from amyloid liver, ceain normal tissues such as human and cattle aoa, and from the urine, liver, and spleen of patients with gargoylism (Hurler's syndrome). This compound has negligible anticoagulant activity. It seems to be structurally similar to heparin, but has a:Lower molecular weight,Some of the amino groups carry acetyl groups and percentage of -SO4 groups are smaller.Unlike heparin, its predominant uronic acid is D-Glucuronic acid (Glc UA).Recently it has been shown that it is present on cell surfaces as proteoglycan and is extracellular.Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 40


Question: Progesterone is synthesized from

Pregnenolone is conveed to progesterone by the action of two smooth endoplasmic reticulum enzymes, 3a-hydroxysteroid dehydrogenase (3a-OHSD) and D5,4-isomerase.Ref: Harper&;s Biochemistry; 30th edition; Page no: 503


Question: DNA is selected for genetic information compared to RNA because

The presence of the oxygen atom in the 2nd carbon of RNA make it more prone to spontaneous hydrolysis DNA is much more stable, the half-life of spontaneous hydrolysis is about 200 million years The possibility of mutations occurring and remaining unidentified is more with uracil since cytosine can be easily deaminated to uracilRef: DM Vasudevan, 7th edition, page no: 576, boxes 44.1


Question: Hydrophobic amino acid is

Amino acids having non-polar side chaindthese include Alanine,Valine,Leucine,Isoleucine,Methionine,Proline,Phenylalanine and Tryptophan.These groups are HYDROPHOBIC (waater repellant) and lipidophilic REFERENCE ; DM VASUDEVAN TEXTBOOK SEVENTH EDITION PAGE NO :26


Question: Kinase require

Mg++ is the activator of many enzymes requiring ATP. Alkaline phosphatase, hexokinase, fructokinase, phosphofructokinase, adenyl cyclase, cAMP-dependent kinases, etc. need magnesium.Ref: DM Vasudevan, Page no: 420


Question: Flouride cause inhibition of


Question: UDP Glucose is formed from

UDP glucose is formed from glucose-1-phosphate and UTP (uridine triphosphate) by the enzyme UDP-glucose pyrophosphorylase.
Reference: Vasudevan 7th  ed, pg 125


Question: Telomerase is

The replication always takes place from 5' to 3' direction in the new strand.The DNA polymerase enzyme is not able to synthesize the new strand at the 5 ' end of the ne2 strand. This end piece of the chromosome is called telomere.Therefore another enzyme , telomere terminal transferase or telomerase takes up this job of replication of the end piece of chromosomes.. The shoening of telomere end is prevented by an enzyme telomerase.It contains an RNA component, which provides the template for telomeric repeat synthesis. REFERENCE DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION ; PAGE NO : 585.


Question: A female on maize as staple diet Its diarrhea and lesion in the neck region It is deficiency of


Question: In humans, the genetic code is represented by code of three nucleotides. If one amino acid is coded 1), more than one triplet, then this is known as

Ans. a. DegeneracyDegeneracyDegeneracy is the redundancy of the genetic codeQThe genetic code has redundancy but no ambiguityQThe codons encoding one amino acid may differ in any of their three positionsQDegeneracyThere are three amino acids encoded by six different codons: serine, leucine and arginineQOnly two amino acids are specified by a single codonQOne of these is the amino-acid methionine, specified by the codon AUG, which also specifies the sta of translation; the other is tryptophan, specified by the codon UGGQThe degeneracy of the genetic code accounts for the existence of synonymous mutationsQDegeneracy results because there are more codons than encodable amino acidsQCodonInitiation codon is AUG (Methionine)QTermination codons: UAA (Ochre), UAG (Ambre), UGA (Opal)Q


Question: Main source of energy in 1min is

Why body stores glucose as glycogen and not as glucose itself? Possible Reasons 1. Being insoluble it exes no osmotic pressure, and so does not disturb the intracellular fluid content and does not diffuse from its storage sites. 2. It has a higher energy level than a corresponding weight of glucose (though energy has to be expended to make it from glucose). 3. It is readily broken down under the influence of hormones and enzyme: * Into glucose in liver (to maintain blood glucose level). * Into lower intermediates in skeletal muscle and other tissues for energy. Role of Liver Glycogen * It is the only immediately available reserve store of blood glucose. * A high liver glycogen level protects the liver cells against the harmful effects of many poisons and chemicals, e.g. CCl4, ethyl alcohol, arsenic, various bacterial toxins. * Ceain forms of detoxication, e.g. conjugation with glucuronic acid; and acetylation reactions, are directly influenced by the liver glycogen level. * The rate of deamination of amino acids in the liver is depressed as the glycogen level rises so that amino acids are preserved longer in that form and so remain available for protein synthesis in the tissues. * Similarly, a high level of liver glycogen depresses the rate of ketone bodies formation. Biomedical Impoance * Liver glycogen is largely concerned with storage and supply of glucose-1-P, which is conveed to glucose, for maintenance of blood glucose, paicularly in between meals. * Muscle glycogen on the other hand, is to act as readily available source of intermediates of glycolysis for provision of energy within the muscle itself. Muscle glycogen cannot directly contribute to blood glucose level. * Inherited deficiency of enzymes in the pathway of glycogen metabolism produces ceain inherited disorders called as Glycogen storage diseases (GSD)Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 346


Question: Botulinum toxin produces skeletal muscle paralysis by

Botulinum toxin B acts by cleaving synaptobrevin, inhibiting release of acetylcholine at the neuromuscular junction


Question: Patient presenting with pellagra, parkinsonism, convulsions, anemia and kidney stones has deficiency of


Question: Glycated haemoglobin reflects blood glucose of preceding

When blood glucose enters the erythrocytes, it glycates the e-amino group of lysyl residues and the amino terminals of haemoglobin.The fraction of haemoglobin glycated, normally about 5%, is propoionate to blood glucose concentration.Since the half-life of an erythrocyte is typically 60 days, the level of glycated haemoglobin (HbA1c) reflects the mean blood glucose concentration over the preceding 6 to 8 weeks. Measurement of HbA1c, therefore, provides valuable information for management of diabetes mellitus.Reference: Harper biochemistry, 30th edition, page no 58


Question: Medium chain fatty acids

Ref: Textbook of Medical Biochemistry 8th Edition Dr (Brig) MN Chatterjea, Rana Shinde page no: 392-396

Require bile salts for absorption and digestion


Question: Enzyme involved in peptide chain synthesis is

Peptide band formation : The alpha aminogroup at the incoming aminoacid in the "A"site forms a peptide bond (CO-NH0 with carboxyl group of the peptidyl tRNA occuping the "P" site.This reaction is catalyzed by the enzyme peptidyltransferase (28S rRNA,a component of 60S subunit). This is an example of ribozyme; RNA acts as the enzyme. Since, the aminoacid brought in by the tRNA is already activated,there is no need for futher energy supply for the purpose of peptidebond formation. Now, the growing peptide chain is occuping the "A" site. REF : DM VASUDEVAN TEXTBOOK ,7th EDITION ,Page no: 601.


Question: Mitochondiral DNA is


Question: 1st carbon of pentose sugar of nucleic acid joins

The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphodiester linkages. In conventional nomenclature, the carbons to which the phosphate groups attach are the 3&;-end and the 5&;-end carbons of the sugar. This gives nucleic acids directionality, and the ends of nucleic acid molecules are referred to as 5&;-end and 3&;-end. The nucleobases are joined to the sugars an N-glycosidic linkage involving a nucleobase ring nitrogen (N-1 for pyrimidines and N-9 for purines) and the 1&; carbon of the pentose sugar ring.Ref: Harper&;s Biochemistry; 30th edition


Question: Not a nucleic acid test

The western blot (sometimes called the protein immunoblot) is a widely used analytical technique used in molecular biology, immunogenetics and other molecular biology disciplines to detect specific proteins in a sample of tissue homogenate or extract Ref-Harpers illustrated biochemistry 30/e p380


Question: The broad beta disease is due to defect in

Name Defect Remarks Familial type III hyperlipoproteinemia (broad beta disease, remnant removal disease, familial dysbetalipoproteinemia Deficiency in remnant clearance by the liver is due to the abnormality in Apo E. Patients lack isoforms E3 and E4 and have only E2, which does not react with the E receptor Increase in chylomicron and VLDL remnants of density <1.019 (b-VLDL). Causes hypercholesterolemia, xanthomas, and atherosclerosis Reference: Harper; 30th edition; Page no: 275


Question: Sanger's reagent is

Sanger's reagent or di-nitro-fluoro-benzene (DNFB) is used for polypeptide sequencing. Other methods of Polypeptide sequencing: Edman's degradation (Edman's reagent is Phenyl-isothiocyanate) - Determine sequence from N-terminal end and can sequence 30-60 amino acid residues. But it cannot work if N-terminal amino acid is chemically modified. Use of various chemical or enzymes to cleave peptides - method used for large polypeptides Mass spectrometry - 3 pas of mass spectrometer are ionization source, mass analyzer and ion detector.


Question: In karyotyping chromosomes are visualized through light microscope with resolution of

Using Karyotypes to Diagnose Genetic Disorders. Using Karyotypes to Diagnose Genetic Disorders. A regular human cell has 46 chromosomes: 44 autosomes, which come in pairs, and 2 sex chromosomes, which specify gender (XX for female and XY for male). The pairs of autosomes are called "homologous chromosomes Ref-Harpers illustrated biochemistry 30/e p582


Question: Substrate level phosphorylation in glycolysis is catalyzed by

In the reaction, catalyzed by phosphoglycerate kinase, phosphate is transferred from 1,3-bisphosphoglycerate onto ADP, forming ATP (substrate-level phosphorylation) and 3-phosphoglycerate. The phosphate of phosphoenolpyruvate is transferred to ADP in another substrate-level phosphorylation catalyzed by pyruvate kinase to form two molecules of ATP per molecule of glucose oxidized. Reference: Harper; 30th edition; Page no: 171

Glyceraldehyde 3 phosphate dehydrogenase


Question: Molecular size of proteins is assessed by

Mass spectrometry (MS) is a very sensitive quantitative analytixal technique used to measure a wide range of clinically relevant analysis.MS identifies molecules based on their mass or molecular size. A sample is vapourized sucj that positive charge is produced on the molecule.Electrical field is applied, so that paiclss move.At the same time , a magnetic field is applied , so the cations are deflected at the right angle to their original direction , and hit on the detector For molecules of identical charge ,the time required for the inversely propoional to the mass of the molecule.Conventional MS identifies molecules of 4000 D or less.For higher moleculer size materials, time-of-flight mass spectrometers are useful Reference:DM VASUDEVAN Text book SEVENTH EDITION pageno : 39 and 458


Question: Porphyrin of normal erythrocyte haemoglobin is

Heme is iron containing protoporphyrin. Protoporphyrins are named according to the side chains, i.e. Methyl, vinyl, propionyl.


Question: A patient of type 2 diabetes mellitus is given nutrition rich in


Question: Immediate precursor of ketone bodies

KETONE BODY FORMATION IN LIVER (KETOGENESIS)Enzymes are mitochondrial:Steps1. Aceto-acetyl-CoA: Aceto-acetyl-CoA is the staing material for ketogenesis. This can arise in two ways:(a) Directly during the course of b-oxidation of fatty acids, or(b) As a result of condensation of two C-2 units, i.e. 'active acetate' (acetyl-CoA) by reversal of thiolase reaction.2. Formation of Acetoacetate: Acetoacetate is the first ketone body to be formed. This can occur in two ways:(a) By deacylation: Acetoacetate can be formed from aceto-acetyl-CoA by simple deacylation catalysed by the enzyme aceto-acetyl-CoA deacylase. The above does not seem to be the major pathway when excessive amount of ketone bodies are formed, the deacylation reaction is not enough to cope up.(b) Second pathway: Formation of acetoacetate intermediate production of "b-OH-b-methyl glutaryl CoA" (HMG-CoA). Present opinion ours the HMG-CoA pathway as the major route of ketone body formation.StepsInvolves two steps:* Condensation of aceto-acetyl-CoA with another molecule of acetyl-CoA to form b-OH-b methyl glutaryl-CoA (HMG-CoA) catalysed by the enzyme HMG-CoA synthase (mitochondrial enzyme).* HMG-CoA is then acted upon by another enzyme, HMG-CoA Lyase, which is also mitochondrial enzyme, to produce one molecule "acetoacetate" and one molecule of acetyl-CoANote* Both the enzymes HMG-CoA synthase and HMG-CoA Lyase are mitochondrial and must be available in mitocondrion for ketogenesis to occur.* Both the enzymes are present in liver cells mitochondria only.* A marked increase in activity of HMG-CoA Lyase has been noted in fasting.* HMG-CoA is a committed step. Cholesterol also can be formed by "HMG-CoA reductase".3. Formation of Acetone: As stated earlier, acetone is formed from acetoacetate by spontaneous decarboxylation (Non-enzymatic). Fig. 25.9: Formation, utilisation, and excretion of ketone bodies4. Formation of b-OH Butyrate: Acetoacetate once formed is conveed to b-OH-butyric acid; the reaction is catalysed by the enzyme b-OH-butyrate dehydrogenase, which is present in liver and also found in many other tissues. b-OH-butyrate is quantitatively the predominant ketone body present in blood and urine in KetosisRef: Textbook of Medical Biochemistry 8th Edition Dr (Brig) MN Chatterjea, Rana Shinde page no 425,426


Question: Richest source of Vitamin D is

Sources of vitamin D: Fish, egg yolk, liver, butter, cheese. Sunlight is also a good source of Vitamin D but upto 50% of the world population is not exposed to sunlight i.e. due to lack of sunlight in some countries and even due to more work load indoors. So this cannot be considered as richest source of Vitamin D. EXTRA READING ON TOPIC (Vitamin D): Active moiety: Calcitriol Main biochemical role: Calcium and Phosphate absorption from intestine and their reabsorption from kidneys. Deficiency: Rickets in children, Osteomalacia in adults, Osteoporosis in elderly


Question: Not an example of substrate level phosphorylation


Question: The main function of mitochondria is

The ETC is localised in the mitochondria. The outer membrane of mitochondria is permeable to most of the small molecules. There is an intermediate space which presents no barrier to passage of intermediates. The inner membrane shows a highly selective permeability. It has transpo systems only for specific substances such as ATP, ADP, pyruvate, succinate, a-ketoglutarate, malate and citrate etc (Refer Fig. 10.1). The enzymes of the electron transpo chain are embedded in the inner membrane in association with the enzymes of oxidative phosphorylation. Extramitochondrial system: This is a radically different and highly active system responsible for de novo synthesis of palmitic acid from 2-carbon unit acetyl-CoA.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th edition, page no: 138 & 414


Question: Sources of the nitrogen in urea cycle are

Sources of Nitrogen in urea are ammonia and aspartate.


Question: Least impoant in final pathway of Electron Chain Reaction is

The electrons are passed through a series of redox reactions, with a small amount of free energy used at three points to transpo hydrogen ions across a membrane. This process contributes to the gradient used in chemiosmosis. ... The endproducts of the electron transpo chain are water and ATP.


Question: Vitamin E is

The E vitamins consist of eight naturally occurring tocopherols, of which a-tocopherol is the most active (Figure 28.28).The primary function of vitamin E is as an antioxidant in prevention of the nonenzymic oxidation of cell components, for example, polyunsaturated fatty acids, by molecular oxygen and free radicalsRef: Lippincott, 5th edition, page no: 391


Question: Thiamine level is best monitored by

The activation of apo-transketolase in erythrocyte lysate by thiamine diphosphate added in vitro has become the accepted index of thiamine nutritional status.


Question: Ion exchange chromatography is based on


Question: Maple syrup urine disease is due to deficiency of

METABOLIC DISORDERS OF BRANCHED-CHAIN AMINO ACID CATABOLISMAs the name implies, the odor of urine in maple syrup urine disease (branched-chain ketonuria, or MSUD) suggests maple syrup, or burnt sugar.The biochemical defect in MSUD involves the a-keto acid decarboxylase complex Plasma and urinary levels of leucine, isoleucine, valine, and their a-keto acids and a-hydroxy acids (reduced a-keto acids) are elevated, but the urinary keto acids derive principally from leucine.Signs and symptoms of MSUD include often fatal ketoacidosis, neurological derangements, mental retardation, and a maple syrup odor of urine.The mechanism of toxicity is unknown.Early diagnosis by enzymatic analysis is essential to avoid brain damage and early moality by replacing dietary protein by an amino acid mixture that lacks leucine, isoleucine, and valine.The molecular genetics of MSUD are heterogeneous. MSUD can result from mutations in the genes that encode E1a, E1b, E2, and E3. Based on the locus affected, genetic subtypesof MSUD are recognized.Type IA MSUD arises from mutations in the E1a gene, type IB in the E1b gene, type II in the E2 gene, and type III in the E3 geneReference: Harper biochemistry page no 309


Question: The pKa values of primary and secondary phosphoryl groups of nucleotides are

The primary and secondary phosphoryl groups of nucleotides have pKa values of about 1.0 and 6.2, respectively. The pKa values of the secondary phosphoryl groups are such that they can serve either as proton donors or as proton acceptors at pH values approximately two or more units above or below neutrality. Reference: Harpers illustrated biochemistry 30th edition


Question: The following is a Ketone body

Under ceain metabolic conditions associated with a high rate of fatty acid oxidation, liver produces considerable quantities of compounds like acetoacetate and b-OH butyric acid, which pass by diffusion into the blood. Acetoacetate continually undergoes spontaneous decarboxylation to produce acetone. These threesubstances are collectively known as "ketone bodies" (or "acetone bodies"). Sometimes also called as "ketones", which is rather a misnomer Ref: M.N. Chatterjea - Textbook of Biochemistry, 8th edition, page no: 425


Question: Common to acyl carrier protein and coenzyme A

Ans. c (Phosphopantotheine is the reactive group). (Ref. Harper's Biochemistry 26th/pg. 173, 495)Pantothenic acid has central role in acyl group metabolism when acting as a functional moiety of coenzyme A or acyl carrier protein (ACP).PANTOTHENIC ACID# The pantothene functional moiety is formed after combination of pantothenate with cysteine, which provides the -SH prosthetic group of CoA and ACP.# CoA takes part in reactions of the citric acid cycle, fatty acid synthesis and oxidation, acetylation, and cholesterol synthesis.# ACP participates in fatty acid synthesis.# Pantothenic acid is widely distributed in all foods, and deficiency has not been unequivocally reported.Educational point:# The fatty acid synthase system is a MULTIENZYME polypeptide complex that incorporates ACP, which takes over the role of CoA and it contains the pantothenic acid in the form of 4-phosphopantetheine.# Co-enzyme A (CoA) is a widely distributed mercaptan containing adenine, ribose, pantothenic acid, and thioethanolamine.

Located in mitochondria as well as cytoplasm


Question: A patient was diagnosed with an isolated increase in LDL. His father and brother had the same disease with increased cholesterol. The likely diagnosis is

LDL receptor mutation

Isolated increase in LDL with positive family history suggests the diagnosis of familial hypercholesterolemia.
Familial hypercholesterolemia (type IIa) is due to deficiency of functional LDL receptors as a result of different types of mutations.

Familial lipoprotein lipase deficiency (type 1)


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

Most reversible inhibitors follow the classic Michaelis-Menten scheme, where an enzyme (E) binds to its substrate(S) to form an enzyme-substrate complex (ES). km is the Michaelis constant that corresponds to the concentration of the substrate when the velocity is half the maximum. Vmax is the maximum velocity of the enzyme. Competitive inhibitors can only bind to E and not to ES. They increase Km by interfering with the binding of the substrate, but they do not affect Vmax because the inhibitor does not change the catalysis in ES because it cannot bind to ES.


Question: Components of 50S ribosomal subunit are

Prokaryotic 70S ribosome made up of 50S (large subunit) made up of 30S (small subunit) made up of 23S RNA 5S RNA 16S RNA


Question: Enzyme deficiency in Von Gierke disease is

Type Name Enzyme Deficiency Clinical Features Ia Von Gierke disease Glucose-6-phosphatase Glycogen accumulation in liver and renal tubule cells Hypoglycemia Lactic acidemia Ketosis Hyperlipidemia Reference: Harper; 30th edition; Table: 18-2; Page no: 179


Question: Nitric acid in synthesized from

Ref-Sathyanarayana 4/e p387 Dietary supplements containing L-arginine have been marketed with the purpose of increasing vasodilatation, and thus, blood and oxygen supply to the exercising muscle. The present study evaluated the acute effect of L-arginine supplementation on indicators of NO production, nitrite (NO2-) + nitrate (NO3-) (NOx), in healthy subjects.


Question: Anticoagulant used to estimate glucose from a sample sent from PHC is

Ans. is 'c' i.e. Potassium oxalate + NaF Repeat from Nov 06The standard anticoagulant used for collection of blood sample for glucose estimation is potassium oxalate.Sodium fluoride is used as a glycolytic inhibitor (At room temperature a loss of 1 to 2% of glucose per hour is expected in the collected blood sample as the RBCs in the sample are still alive and extracting glucose for glycolysis. This gives a false low value of blood glucose. Sodium fluoride is added to inhibit glycolysis)

Chemistry of Carbohydrates, Amino sugars, and Mucopolysaccharides


Question: Glucose may be synthesised from

Glycerol is release during the hydrolysis of triacylglycerols in adipose tissue and is delivered by the blood to the liver, where it is used in the synthesis of glucose by gluconeogenesis.


Question: Fructose intolerance is due to deficiency of

Fructose intolerance is due to deficiency of aldolase-B.Incidence out of 1 is 20,000.It is an autosomal recessive inborn error of metabolism.Fructose-1-phosphate cannot be metabolized.Accumulation of fructose -1-phosphate will inhibit glycogen phosphorylase.Ref: DM Vasudevan, 7th edition, page no: 144


Question: Vitamin causing Encephalomalacia


Question: Intracellular soing and packing done by

The Golgi apparatus plays two major roles in protein synthesis. First, it is involved in the processing of the oligosaccharide chains of membrane and other N-linked glycoproteins and also contains enzymes involved in O-glycosylation.Second, it is involved in the soing of various proteins prior to their delivery to their appropriate intracellular destinations.All pas of the Golgi apparatus paicipate in the first role, whereas the trans-Golgi network (TGN) is paicularly involved in the second and is very rich in vesicles.Ref: Harper 30th edition pg: 608


Question: Branded chain ketoacid decarboxylation is defective in

Maple Syrup Urine Disease (MSUD) i. It is also called branched-chain ketonuria. The incidence is 1 per 1 lakh bihs. The name originates from the characteristic smell of urine (similar to burnt sugar or maple sugar) due to excretion of branched-chain keto acids. ii. The basic biochemical defect is deficient decarboxylation of branched-chain keto acids (BKA). iii. Clinical findings: Disease stas in the first week of life. It is characterized by convulsions, severe mental retardation, vomiting, acidosis, coma and death within the first year of life. iv. Laboratory findings: Urine contains branched chain keto acids, valine, leucine, and isoleucine. Rothera&;s test is positive, but unlike in cases of ketoacidosis, even boiled and cooled urine will give the test. Diagnosis depends on enzyme analysis in cells. Diagnosis should be done prior to 1 week after bih. v. Treatment: Giving a diet low in branched chain amino acids. Mild variant is called intermittent branched-chain ketonuria. This will respond to high doses of thiamine. This is because the decarboxylation of the BKA requires thiamine. Liver transplantation has been successfully tried in some cases of MSUD.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 200


Question: Maple syrup urine disease is due accumulation of

Maple syrup urine disease is also called branched-chain ketonuria The basic defect is deficient decarboxylation of branched-chain ketoacids.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 230


Question: Arachidonic acid is synthesized from

Essential Fatty Acids (EFA) Normal dietary allowance of PUFA is 2-3% of total calories. Linoleic acid (o6, 18C, D 9,12) and linolenic acid (o3, 18C, D 9,12,15) are the only fatty acids which cannot be synthesized in the body. They have to be provided in the food; hence they are essential fatty acids. Arachidonic acid can be formed if the dietary supply of linoleic acid is sufficient PUFA may be formed from monounsaturated fatty acids by the introduction of double bonds only between an existing double bond and carboxyl end of the fatty acid (but not between the omega end and an existing double bond). Hence linoleic acid cannot be synthesized from oleic acid. However, linoleic acid can be conveed to arachidonic acidRef: DM Vasudevan - Textbook of Biochemistry, 6th Edition, page no: 162


Question: Type of collagen in Basement membrane

Ref: Harper&;s Biochemistry; 30th edition; Chapter 50; The Extracellular Matrix


Question: Phenylketonuria is caused by deficiency of

Deficiency of Phenylalanine hydroxylase is the cause of PKU. The genetic mutation may be in such a way that either the enzyme is not synthesized or a non-functional enzyme is synthesized.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 236


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

Maximal buffering capacity occurs at pH equal to pka of buffer. Therefore, to work as a best buffer at physiological pH amino acid should have pka value close to physiological pH (7.4). Amino acids can have buffering action due to three ionizable groups :- 1) a-carboxyl group- Different amino acids have pka value of c-carboxyl group between 3.5-4. So carboxyl group of amino acids has maximum buffering capacity between pH 3.5-4. 2) a-amino group :- Different amino acids have pka value of c-amino group between 8.0-9.0. Thus, a-amino group has maximum buffering capacity between pH 8.0-9.0. 3) Special ionizable group (in some amino acids) - Among special ionizable group of amino acids, imidazole group of histidine has pka value 6.5-7.4, which is closest to physiological pH. Hence, histidine (due to imidazole group) has maximum buffering capacity at physiologial pH.


Question: Enediols are formed by treating the sugars with

In carbohydrate chemistry, the Lobry de Bruyn-van Ekenstein transformation also known as the Lobry de Bruyn-Alberda-van Ekenstein transformation is the base or acid catalyzed the transformation of an aldose into the ketose isomer or vice versa, with a tautomeric enediol as a reaction intermediate. Ketoses may be transformed into 3-ketoses, etcetera. The enediol is also an intermediate for the epimerization of an aldose or ketose.Mild alkaline conditions, Aldehyde or keto groups will tautomerize to form enediols.Enediols are highly reactive. So sugars are powerful reducing agents in alkaline condition.Ref: Harper&;s Biochemistry; 30th edition


Question: In vivo control of citric cycle is affected by

Regulation of TCA Cycle 1. As the primary function of TCA cycle is to provide energy, respiratory control the ETC and oxidative phosphorylation exes the main control. SECTION FOUR 2. In addition to this overall and coarse control, several enzymes of TCA cycle are also impoant in the regulation. Three Key enzymes are: * Citrate synthase * Isocitrate dehydrogenase (ICD) *aaa-oxoglutarate dehydrogenase These enzymes are responsive to the energy status as expressed by the ATP/ADP ratio and NADH/NAD+ ratio * Citrate synthase enzyme is allosterically inhibited by ATP and long-chain acyl-CoA. * NAD+-dependent mitochondrial isocitrate dehydrogenase (ICD) is activated allosterically by ADP and is inhibited by ATP and NADH. * a-oxoglutarate dehydrogenase regulation is analogous to PDH complex. 3. In addition to above, succinate dehydrogenase enzyme is inhibited by OAA and the availability of OAA is controlled by malate dehydrogenase, which depends on NADH/NAD+ ratio. Most of ATP is formed as a result of oxidative phosphorylation resulting from re-oxidation of reduced coenzymes, viz., NADH and FADH2 by the respiratory chain. The remainder is generated by Phosphorylation at substrate level.Ref: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 342 & 343


Question: NADPH is required in

Generation of Reducing Equivalents The major metabolic role of the pathway is to provide cytoplasmic NADPH for reductive biosynthesis of fatty acids, Co-enzymes of Fatty Acid Synthesis An impoant point to remember is that the co-enzyme utilised for de novo synthesis is NADPH. The sources of NADPH for fatty acidsynthesis are:Pentose Phosphate Pathway This is the main source. Tissues having active lipogenesis (liver, adipose tissue, lactating mammary gland) have an active HMP shunt pathway also.Malic Enzyme Malate + NADP+- Pyruvate + CO2 + NADPH + H+ The reaction also helps to transfer cytoplasmic oxaloacetate to the mitochondria. For every molecule of acetyl CoA delivered to the cytoplasm, one molecule of NADPH is formed and reducing equivalents are generated in cytoplasmRef: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 116, 139


Question: Invert sugar, is

Hydrolysis of sucrose (optical rotation +66.5°) will produce one molecule of glucose (+52.5°) and one molecule of fructose (–92°).
Therefore, the products will change the dextrorotation to levorotation, or the plane of rotation is inverted. Equimolecular mixture of glucose and fructose thus formed is called invert sugar. The enzyme producing hydrolysis of sucrose is called sucrase or invertase.
Honey contains invert sugar. Invert sugar is sweeter than sucrose.
Reference: Vasudevan 7th  ed, pg 77

equimolar mixture of glucose and fructose

equimolar mixture of Sucrose and glucose

equimolar mixture of Glucose and lactose


Question: Heme in hemoglobin is in the

Hemoglobin is found exclusively in red blood cells (RBC), where its main function is to transpo oxygen (O2) from the lungs to the capillaries of the tissues. Hemoglobin A, the major hemoglobin in adults, is composed of four polypeptide chains (two a chains and two b chains) held together by noncovalent interactions. Each chain (subunit) has stretches of a-helical structure and a hydrophobic heme-binding pocket similar to that described for myoglobin. Ref: LIPPINCOTT's Biochemistry 6th Edition page no. 27


Question: Casal's necklace' is seen in the following disease

The Casal necklace is an erythematous pigmented skin rash in the distribution of a broad collar (dermatomes C3 and C4). It is seen in patients with pellagra. It occurs as a result of niacin (vitamin B-3) deficiency. Pellagra is a disease characterised by diarrhoea, dermatitis and dementia. Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 138-141


Question: Xanthoproteic reaction involves

Xanthoproteic reaction is method for determination of amount of protein soluble in solution, using concentrated nitric acid.


Question: Xeroderma pigmentosum is produced as a result of a defect in

It is derived from the Greek terms xeres = dry and derma = skin. It is an autosomal recessive condition. Defect lies in the NER (nucleotide excision repair) mechanism. There are seven XP genes (A to G) necessary for NER mechanism in humans. Mutation in any one of them may lead to the condition XP. UV light (sun light) causes formation of thymine dimers, where covalent bonds are formed between adjacent thymine residues. Since repair mechanism is not operating, these mutations are accumulated, leading to cancer. There is sensitivity to ultraviolet rays; sunlight causes blisters on the skin. Avoiding sunlight and using sunscreen ointment will be beneficial. Patients with XP have a 1000-fold greater chance of developing skin cancer than do normal persons. Death usually occurs in the second decade of life due to squamous cell carcinoma of skin. Prenatal diagnosis of XP is possible.Ref: DM Vasudevan, page no: 479


Question: Homocystein is not associated with

Ans. is 'c' i.e., Hearing lossElevated level of homocysteine (hyperhomocysteinemia) is associated with -i) Thrombosis, coronary aery disease & stroke.ii) Osteoporosis & fracture.iii) Neuropsychiatric manifestations.iv) Developmental delay.v) Visual disturbances.vi) Microalbuminuria.


Question: Pyruvate formation is associated with aminoacid

Phenylalanine, methionine, threonine, proline


Question: A protein to be secreted from the cell is most likely to have

A protein to be secreted from the cell usually has a hydrophobic region at its amino terminus, which causes the ribosome synthesizing that protein to become bound to the endoplasmic reticulum. The protein molecule enters the endoplasmic reticulum as it is being made. The signal sequence is cleaved off by the signal peptidase and carbohydrate residues are attached inside the endoplasmic reticulum. Additional carbohydrate residues are attached as the protein moves through the Golgi apparatus on its way to the outside of the cell. Proteins that are destined for the lysosomes are marked by the addition of mannose-6-phosphate. Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 553

A hydrophilic signal sequence at its carboxyl terminus

A hydrophobic signal sequence at its amino terminus

A binding site for the mitochondrial membrane


Question: The major fuel for the brain after several weeks of starvation

The major fuel for brain in prolonged starvation is ketone bodies (Beta hydroxybutyrate, acetoacetate).


Question: Krabbe’s disease caused by deficiency of


Question: Vitamin A toxicity causes


Question: Cardiolipin is associated with


Question: Fluid mosaic model was proposed by

Proposed by Singer and Nicolson. This model is likened to integral membrane protein 'icebergs' floating in a sea of predominantly fluid phospholipid molecules. At normal body temperature (37 0 C) the lipid bilayer is in a fluid state. The longer and more saturated fatty acid chains cause higher values of transition temperature.


Question: Glycine is used in the synthesis of

The whole of glycine is incorporated into the purine ring. (C4, C5, and N7)Ref: DM Vasudevan - Textbook of Biochemistry for Medical Students, 7th edition, page no: 212


Question: Enzymes in glycogen metabolism

The liver phosphorylase-b is the inactive form. It becomes active on phosphorylation. The active enzyme is denoted as phosphorylase-a.Ref: DM Vasudevan, page no: 127


Question: Desired ratio of total cholesterol/HDL should be

HDL-cholesterol level HDL level above 60 mg/dl protects against hea disease. Hence HDL is "good" cholesterol. A level below 40 mg/dl increases the risk of CAD. For every 1 mg/dl drop in HDL, the risk of hea disease rises 3%. If the ratio of total cholesterol / HDL is more than 3.5, it is dangerous. Similarly, LDL: HDL ratio more than 2.5 is also detrimental.Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 295


Question: One of the following groups of enzymes does not exhibit stereospecificity

All enzymes (except isomerases) exhibit stereospecificity, that reacts only with one set of stereoisomers.Whereas isomerases conve substrate from one isomerase to another. Harper 30th edition pg: 60


Question: Long chain fatty acid is transported into inner mitochondria membrane by

Acyl carnitine

Activated long chain fatty acid (acyl CoA) cannot penetrate the inner mitochondrial membrane.
Acyl group of acyl CoA is transferred to carnitine, resulting in the formation of acylcarnitine.

Acylcarnitine is then transported across the inner mitochondrial membrane into the mitochondrial matrix by translocase.

Once inside the mitochondrion, an acyl group of acylcarnitine is transferred back to CoA, resulting in the formation of acyl-CoA which undergoes β -oxidation.


Question: Compound that joints glycolysis with glycogenesis and glycogenolysis is


Question: Essential pentosuria occurs due to defect in the metabolic pathway of

Ans. a (Uronic acid) (Ref. Harper's, Biochemistry, 26th ed., 105, 163, 170; 27th/ 177; H-18th/Table 364-1)ESSENTIAL PENTOSURIA# In liver, the uronic acid pathway catalyzes the conversion of glucose to glucuronic acid, ascorbic acid, and 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.# Glucuronic acid is synthesized from glucose via the uronic acid pathway, which is of major significance for the excretion of metabolites and foreign chemicals (xenobiotics) such as glucuronides. A deficiency in this pathway leads to essential pentosuria.# In this rare hereditary disease, 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.# Various drugs markedly increase the rate at which glucose enters the uronic acid pathway.- For example, administration of barbital or of chlorobutanol to rats results in a significant increase in the conversion of glucose to glucuronate, L-gulonate, and ascorbate.ESSENTIAL FRUCTOSURIA# The lack of one enzyme of the pathway (gulonolactone oxidase) in primates and some other animals explains why ascorbic acid is a dietary requirement for humans but not most other mammals.# Deficiencies in the enzymes of fructose and galactose metabolism lead to essential fructosuria and the galactosemias.INHERITED DISORDERS OF AMINO ACID METABOLISMAmino acid(s)ConditionEnzyme DefectClinical FindingsInheritancePhenylalaninePhenylketonuriaPhenylalanine hydroxylaseMental retardation, microcephaly, hypopigmented skin and hairs, eczema, "mousy" odorAR DHPR deficiency hyperphenylalaninemiaDihydropteridine reductaseMental retardation, hypotonia, spasticity, myoclonusAR PTS deficiency hyperphenylalaninemia6-Pyruvoyl-tetrahydropterinsynthaseDystonia, neurologic deterioration, seizures, mental retardationAR GCH1 deficiency hyperphenylalaninemiaGTP cyclohydrolase 1Mental retardation, seizures, dystonia, temperature instabilityAR Carbinolamine dehydratase deficiencyPterin-4-carbinolaminedehydrataseTransient hyperphenylalaninemia (benign)ARTyrosineTyrosinemia type I (hepatorenal)Fumary -lacetoacetatehydrolaseLiver failure, cirrhosis, rickets, failure to thrive, peripheral neuropathy, "boiled cabbage" odorAR Tyrosinemia type II (oculocutaneous)Tyrosine transaminasePalmoplantar keratosis, painful corneal erosions with photophobia, mental retardation (?)AR Tyrosinemia type III4-HydrophenylpyruvateDioxygenaseHypertyrosinemia with normal liver function, occasional mental delayAR Hawkinsinuria4-Hydroxyphenylpyruvate DioxygenaseTransient failure to thrive, metabolic acidosis in infancyAD AlkaptonuriaHomogentisic acid oxidaseOchronosis, arthritis, cardiac valve involvement, coronary artery calcificationAR Albinism(oculocutaneous)TyrosinaseHypopigmentation of hair, skin, and optic fundus; visual loss; photophobiaAR Albinism (ocular)Different enzymes or transportersHypopigmentation of optic fundus, visual lossAR, XL DOPA-responsive DystoniaTyrosine hydroxylaseRigidity, truncal hypotonia, tremor, mental retardationARGABA4-Hydroxybutyric AciduriaSuccinic semialdehyde dehydrogenaseSeizures, mental retardation, ataxiaARTryptophanKynurenic aciduriaKynurenine-3-monooxygenaseNiacin deficiency, pellagra, colitisAR Hydroxykynureninuria(xanthurenic aciduria)KynureninaseNiacin deficiency, mental retardation, spasticityARHistidineHistidinemiaHistidine-ammonia lyaseBenignAR Urocanic aciduriaUrocanaseBenignAR Formiminoglutamic aciduriaFormi mi notransferaseOccasional mental retardationARGlycineGlycineencephaiopathyGlycine cleavage (4 enzymes)Infantile seizures, lethargy, apnea, profound mental retardationAR SarcosinemiaSarcosine dehydrogenaseBenignAR Hyperoxaluria type IAlanine:glyoxylateaminotransferaseCalcium oxalate nephrolithiasis, renal failureAR Hyperoxaluria type IId-Glyceric acid dehydroge- nase/ glyoxylate reductaseCalcium oxalate nephrolithiasis, renal failureARSerinePhosphoglycerate dehydrogenase deficiencyPhosphoglycerate dehydrogenaseSeizures, microcephaly, mental retardationARProlineHyperprolinemia type IProline oxidaseBenignAR Hyperprolinemia type IIl-Pyrroline-5-carboxylate dehydrogenaseFebrile seizures, mental retardationAR HyperhydroxyprolinemiaHydroxyproline oxidaseBenignAR Prolidase deficiencyProlidaseMild mental retardation, chronic dermatitisARMethionineHypermethioninemiaMethionine adenosyltransferaseUsually benignAR S-Adenosylhomocysteine hydrolase deficiencyS-Adenosylhomocysteine hydrolaseHypotonia, mental retardation, absent tendon reflexes, delayed myelinationAR Glycine N-methyltrans- ferase deficiencyGlycine N-methyltransferaseElevated liver transaminasesARHomocystineHomocystinuriaCystathionine -synthaseLens dislocation, thrombotic vascular disease, mental retardation, osteoporosisAR Homocystinuria5,10-Methylenetetrahydro- folate reductaseMental retardation, gait and psychiatric abnormalities, recurrent strokesAR HomocystinuriaMethionine synthase (cbIE, -G)Mental retardation, hypotonia, seizures, megaloblastic anemiaAR Homocystinuria and methylmalonic acidemiaVitamin B12 lysosomal efflux and metabolism (cbIC, -D, -F)Mental retardation, lethargy, failure to thrive, hypotonia, seizures, megaloblastic anemiaARCystathionineCystathioninuriaCystathionaseBenignARCystineCystinosisCystinosin CTNS (lysosomal efflux)Renal Fanconi syndrome, rickets, photophobia, hypotonia, renal failureARS-Sulfo-I- cysteineSulfocysteinuriaSulfate oxidase or molybdenum cofactor deficiencySeizures, mental retardation, dislocated lensesARLysineHyperlysinemia, saccharopinuriaAminoadipic semialdehyde synthaseBenignAR Pyridoxine-dependent seizuresL-l-Piperideine-6-carboxylate dehydrogenaseSeizuresARLysine, tryptophanKetoadipic acidemiaKetoadipic acid dehydrogenaseBenign? Glutaric acidemia type IGlutaryl-CoA dehydrogenaseSevere dystonia and athetosis, mild mental retardationAR Glutaric acidemia type IIElectron transfer flavoprotein (ETF) or ETF:ubiquinone oxidoreductaseHypoglycemia, metabolic acidosis, "sweaty feet" odor, hypotonia, cardiomyopathy, exercise-induced myopathyAROrnithineGyrate atrophy of the choroid and retinaOrnithine 5 aminotransferaseMyopia, night blindness, loss of peripheral vision, cataracts, chorioretinal degenerationARUrea cycleCarbamoylphosphate synthase-1 deficiencyCarbamoylphosphate synthase-1Lethargy progressing to coma, protein aversion, mental retardation, hyperammonemiaAR N-Acetylglutamate synthase deficiencyN-Acetylglutamate synthaseLethargy progressing to coma, protein aversion, mental retardation, hyperammonemiaAR Ornithine transcar- bamylase deficiencyOrnithine transcarbamylaseLethargy progressing to coma, protein aversion, mental retardation, hyperammonemiaXL Citrullinemia type 1Argininosuccinate synthaseLethargy progressing to coma, protein aversion, mental retardation, hyperammonemiaAR Argininosuccinic acidemiaArgininosuccinate lyaseLethargy progressing to coma, protein aversion, mental retardation, hyperammonemia, trichorrhexis nodosaAR Arginase deficiencyArginaseSpastic tetraparesis, mental retardation, mild hyperammonemiaAR Hyperornithinemia, hyperammonemia, homocitrullinuriaMitochondrial ornithine carrier ORNT1Vomiting, lethargy, failure to thrive, mental retardation, episodic confusion, hyperammonemia, protein intoleranceAR Citrullinemia type 2Mitochondrial aspartate/ glutamate carrier CTLN2Neonatal intrahepatic cholestasis, adult presentation with sudden behavioral changes and stupor, coma, hyperammonemiaARProline, ornithine, argininel-pyrroline-5-carboxylate synthase deficiencyl-pyrroline-5-carboxylate synthaseHypotonia, seizures, hyperammo- nemia, neurodegenerationARGlutamineGlutamine synthase deficiencyGlutamine synthaseBrain malformations, pachygyria, seizures, hypotonia, dysmorphic featuresARValineIsobutyryl-CoA dehydro- genase deficiencyIsobutyryl-CoA dehydrogenaseFailure to thrive, anemia, and dilated cardiomyopathy(?)ARValine, leucine, isoleucineMaple syrup urine diseaseBranched chain ketoacid dehydrogenaseLethargy, vomiting, encephalopathy, seizures, mental retardation, "maple syrup" odor, protein intoleranceARLeucineIsovaleric acidemiaIsovaleryl-CoA dehydrogenaseAcidosis, ketosis, vomiting, coma, hyperammonemia, "sweaty feet" odor, protein intoleranceAR 3-Methylcrotonyl glycinuria3-Methylcrotonyl-CoA carboxylaseStress-induced metabolic acidosis, hypotonia, hypoglycemia, "cat's urine" odorAR 3-Methyfglutaconic aciduria type 13-Methylglutaconyl-CoA hydratase deficiencyStress-induced acidosis, leukoencephalopathyAR 3-Hydroxy-3-methylglutaricaciduria3-Hydroxy-3-methylglutaryl- CoA lyaseStress-induced hypoketotic hypoglycemia and acidosis, encephalopathy, hyperammonemiaARIsoleucine2-Methylbutyryl-glycinuria2-Methylbutyryl-CoA dehydrogenaseFasting-induced metabolic acidosis/hypoglycemiaAR 2-Methyl-3-hydroxybutyryl- CoA dehydrogenase deficiency2-Methyl-3-hydroxybutyryl- CoA dehydrogenaseDevelopmental regression, seizures, and rigidity sometimes triggered by illnessesXL 3-Oxothiolase deficiency3-OxothiolaseFasting-induced acidosis and ketosis, vomiting, lethargyARValine, isoleucine, methionine, threoninePropionic academia (pccA,-B,-C)Propionyl-CoA carboxylaseMetabolic ketoacidosis, hyperammonemia, hypotonia, lethargy, coma, protein intolerance, mental retardation, hyperglycinemiaAR Multiple carboxylase/ biotinidase deficiencyHolocarboxylase synthase or biotinidaseMetabolic ketoacidosis, diffuse rash, alopecia, seizures, mental retardationAR Methylmalonic acidemia {mutase, racemase, CbIA, -B, -D)Methylmalonyl-CoA mutase/ racemase or cobalamin reductase/ adenosy (transferaseMetabolic ketoacidosis, hyperammonemia, hypertonia, lethargy, coma, protein intolerance, mental retardation, hyperglycinemia


Question: Collagen present in skin is

Collagen * Collagen is the most abundant protein in the human body, have a triple helical structure * At least 28 distinct types of collagen made up of over 30 distinct polypeptide chains have been identified in human tissues * The main fibril forming collagens in skin and bone and in cailage, respectively, are types I and II. Ref:- Harper 30/e; pg num:- 628 , Lippincott 7/e; Pg Num:- 44


Question: Examples of monounsaturated fatty acids are

Monounsaturated (Monoethenoid) fatty acids: They contain one double bond. Their general formula is Cn H2n-1 COOH Example: Oleic acid C17H33 COOH is found in nearly all fats (formula 18: 1; 9)Ref: M.N. Chatterjee - Textbook of Biochemistry, 8th edition, page no: 47


Question: The 3 dimensional shape of a protein is maintained mainly bya) Strong covalent interactionsb) Interactions with other proteinsc) Multiple weak interactionsd) Interactions with prosthetic groups

Both weak noncovalent interactions and strong covalent bonds stabilize the tertiary structure of the protein (which provides three-dimensional shape).
The major forces stabilizing tertiary structure (which provides three-dimensional shape) are multiple weak noncovalent interactions:- Hydrogen bonds, hydrophobic interactions, ionic bond, and Van der Waals forces.
Covalent (Disulfide) bonds also provide some stability.


Question: Cancer cells derive nutrition from

In fast-growing cancer cells, glycolysis proceeds at a high rate, forming large amounts of pyruvate, which is reduced to lactate and expoed. This produces a relatively acidic local environment in the tumor, which may have implications for cancer therapy. The lactate is used for gluconeogenesis in the liver, an energy-expensive process, which is responsible for much of the hypermetabolism seen in cancer cachexia. Reference: Harper; 30th edition; Page no: 168


Question: Fructose is transported by


Question: The following substance acts as a 'satiety signal' for lipids

Enterostatin, a peptide that selectively reduces fat intake. It is formed in the intestine by the cleavage of secreted pancreatic procolipase, the remaining colipase serving as an obligatory cofactor for pancreatic lipase during fat digestion. After feeding, enterostatin appears in the lymph and circulation. Enterostatin will selectively inhibit fat intake during normal feeding and in experimental paradigms that involve dietary choice. Both peripheral and central sites of action have been proposed. The peripheral mechanism involves an afferent vagal signaling pathway to hypothalamic centers. The central responses are mediated through a pathway that includes both serotonergic and opioidergic components. Chronically, enterostatin reduces fat intake, body weight, and body fat. This response may involve multiple metabolic effects of enterostatin, which include a reduction of insulin secretion, an increase in sympathetic drive to brown adipose tissue, and the stimulation of adrenal coicosteroid secretionReference: Enterostatin-a peptide regulating fat intake; Erlanson-Albesson C, York D; Obes Res.1997 Jul;5(4):360-72


Question: Detection of proteins by the following methods does not affect its function

Option analysis: * Sodium dodecyl sulfate is a protein denaturing agent - option a is excluded Heat coagulation result in loss of higher level of structures other than primary structure - option b is excluded 2-D electrophoresis is SDS-PAGE in one dimension and isoelectric focusing in other dimension - option c is excluded Hence the answer is UV light. In this, protein solution is exposed to UV light and amino acids in protein absorb UV light which can be measured using a spectrophotometer. This technique does not affect the structure of proteins hence does not affect its function.

Detecting with Coomassie blue dye after electrophoresis by SDS-PAGE


Question: The proteins present in Deoxyribonucleic acid is

Histones are proteins containing unusually higher concentration of basic amino acid. Albumins and globulins are plasma proteins Protamines are small, arginine-rich, nuclear proteins that replace histonesRef: DM Vasudevan, 7th edition, page no: 576, 578


Question: The apoprotein associated with LCAT is

Lecithin: cholesterol acyltransferase (LCAT) activity is associated with HDL containing apo A-I. As cholesterol in HDL becomes esterified, it creates a concentration gradient and draws in cholesterol from tissues and from other lipoproteins, thus enabling HDL to function in reverse cholesterol transpo. Reference: Harper; 30th edition; Page no: 272


Question: Vitamin neede for acetyl CoA carboxylase is

Biotin acts as co-enzyme for carboxylation reactions. Biotin captures a molecule of CO2 which is attached to nitrogen of the biotin molecule (Fig. 34.14). The energy required for this reaction is provided by ATP. Details of the reaction are given in Figure 34.15. Then the activated carboxyl group is transferred to the substrate.Biotin Requiring CO2 Fixation Reactions 1. Acetyl CoA carboxylase This enzyme adds CO2 to acetyl CoA to form malonyl CoA. This is the rate-limiting reaction in biosynthesis of fatty acids (Step 1, Fig. 11.15). Acetyl CoA +CO2+ATP- Malonyl CoA + ADP+PiRef: DM Vasudevan - Textbook of Biochemistry, page no: 399


Question: The major storage form of fatty acids in the body are

(A) Triacylglycerols [UNS: - 33; Harrison'7 - 2197; Harrison11 - 2878; Harrison16 - 2077


Question: The main apolipoprotein of LDL is

The major apolipoproteins of HDL (a-lipoprotein) are apoAs. The main apolipoprotein of LDL (b-lipoprotein) is apo B (B-100), which is found also in VLDL. Chylomicrons contain a truncated form of apo B (B-48) that is synthesized in the intestine, while B-100 is synthesized in the liver. Apo E, found in VLDL, HDL, chylomicrons, and chylomicron remnants, is also freely transferable. Reference: Harper; 30th edition; Page no: 255


Question: Fluoride ions act by inhibiting

Enolase is inhibited by fluoride, and when blood samples are taken for measurement of glucose, glycolysis is inhibited by taking the sample into tubes containing fluoride. Enolase is also dependent on the presence of either Mg2+ or Mn2+ ions. Reference: Harper; 30th edition; Page no: 171


Question: Nieman pick disease is due to deficiency of

Some examples of sphingolipidoses Disease :Niemann-Pick disease Enzyme deficiency: Sphingomyelinase Lipid accumulating Sphingomyelin Clinical symptoms: Enlarged liver and spleen, mental.Ref: Textbook of Medical Biochemistry, Eighth Edition, Dr (Brig) MN Chatterjea, page no: 63 Table 4.2:


Question: Vitamin D

Synthesis is regulated at the reaction catalyzed by 15-hydroxylase

Along with PTH, increases calcium resorption from bone


Question: Not a substrate for gluconeogenesis

Substrates for gluconeognesis Lactate All amino acids except leucine and lysine Pyruvate Propionate Glycerol Intermediates of citric acid cycle Alanine is the most impoant gluconeogenic amino acid. REF: Lippincott book of biochemistry 6th ed.


Question: Collagen in basement membrane


Question: Function of coenzyme is to

Enzymes may be simple proteins , or complex enzymes, containing a non -protein pa, called the prosthetic group. The prosthetic group is called the co-enzyme.It is heat stable. The protein pa is named as apoenzyme.It is heat labile.The two poions combined together are called the HOLOENZYME. First group of co-enzymes: In the first group , the change occuring in the substrate is counter balanced by the co-enzymes.Therefore,such co-enzymes may be called as co-substrates or secondary substrates. These takes pa in reactions catalyzed by oxido-reductases by donating or accepting hydrogen atoms or electrons. Second group of coenzymes : These coenzymes take pa in reactions transferring groups other than hydrogen. A paicular group or radical is transferred from the substrate to another substrate. REFERENCE :DM VASUDEVAN TEXTBOOK EIGHTH EDITION , Page no :54


Question: Von Geirke's disease occurs due to deficiency of

Ans. a (Glucose-6-Phosphatase) (Ref. Harper 28th/160; 298; Table 19-2)Von Gierke disease (type i) is a Autosomal recessive disease that occurs due to Glucose-6-phosphatase and characterized by Severe fasting hypoglycemia, glycogen in liver, blood lactate, hepatomegaly. Treatment: frequent oral giucose/cornstarch; avoidance of fructose and galactose.Glycogen storage disordersTypeNameEnzyme DeficiencyClinical Features0--Glycogen synthaseHypoglycemia; hyperketonemia; early deathIVon Gierke's diseaseGlucose 6-phosphataseGlycogen accumulation in liver and renal tubule cells; Hyperlipemia, Hyperuricemia Hypoglycemia; Lactic acidemia; ketosis;IIPompe's diseaseLysosomal-1-4 and 1-6 glucosidase (acid maltase)Accumulation of glycogen in lysosomes: juvenile onset variant, muscle hypotonia, death from heart failure by age 2;Q adult onset variant, muscle dystrophyIIILimit dextrinosis, Forbe's or Cori's diseaseDebranching enzyme QFasting hypoglycemia; hepatomegaly(infancy); accumulation of characteristic branched polysaccharideIVAmylopectinosis, Andersen's diseaseBranching enzymeHepatosplenomegaly;accumulation-of polysaccharide with few branch points; death from heart or liver failure in first year of lifeVMyophosphorylase defici McArdle's syndrome0Muscle phosphorylasePoor exercise tolerance; muscle glycogen abnormally high (2.5-4%) Q; blood lactate very low after exerciseVIHers' diseaseLiver phosphorylaseHepatomegaly; accumulation of glycogen in liver; mild hypoglycemia; generally good prognosisVIITarui's diseaseMuscle and erythrocyte phosphofructokinase 1Poor exercise tolerance; muscle glycogen abnormally high (2.5-4%); blood lactate very low after exercise; also hemolytic anemiaVIII Liver phosphorylase kinaseHepatomegaly; accumulation of glycogen in liver; mild hypoglycemia; good prognosisIX Liver and muscle phosphorylase kinaseHepatomegaly; accumulation of glycogen in liver and muscle; mild hypoglycemia; generally good prognosisX cAMP-dependent protein kinase AHepatomegaly; accumulation of glycogen in liver


Question: Inhibitor of F0F1 ATPase in electron transpo chain is

Oligomycin is a group of Streptomyces macrolides that bind to the Oligomycin sensitivity-conferring protein (OSCP) at the F(o) subunits 6 and 9 which are found in the stalk of the F1F0-ATPase complex. This binding blocks proton conductance across the synthase complex and inhibits the synthesis of mitochondrial ATP. As an additional result, the proton pumps of the electron transpo chain are unable to operate because the gradient becomes too strong for them to overcome. NADH is then no longer oxidized and the citric acid cycle ceases to operate because the NAD+ concentrationfalls below the concentration that these enzymes can use.1,2


Question: Okazaki fragments are

Okazaki fragments are short pieces of DNA that are synthesized on lagging strand and later these small pieces are joined together by DNA ligase.


Question: Glycogen storage diseases include the following


Question: Most basic amino acid out of the following is

Arginine is the most basic amino acid with pk value of side chain (R) 12.5
Aspartic acid is the most acidic amino acid with pk value of side chain (R) 3.9


Question: The term modified base refers to

A modified base is one that has been modified after nucleic acid chain has been formed. These bases are modified by methylation, reduction, acetylation or glycosylation.
In t-RNA there are many modified bases, e.g. dihydrouridine, ribothymidine, pseudouridine, and 7-methylguanosine.
In DNA, the most common modified base is 5-methylcytosine.
Other important modified bases are acetylcytosine and dimethyladenine.

Purine or pyrimidine attached to deoxyribose

A purine or pyrimidine that has been altered

A nitrogen containing ring other than a purine or pyrimidine that is part of a nucleotide

A purine or pyrimidine attached to a sugar by O-glycoside linkage


Question: Cori's cycle is concerned with transport of

Cori's cycle (Glucose-Lactate cycle) is concerned with transport of Lactate.


Question: In estimation of bilirubin, the solution is examined at

Ans: b (450nm) Ref: Vasudevan 4th ed/p.480The characteristic absorption maximums of some importantsubstances are:- Protein, peptide linkage- 220 nmProtein, tryptophan units- 280 nmNucleic acids- 260 nmDeoxy haemoglobin- 565 nmBilirubin- 450 nmNADH- 340 nmFAD- 450 nmFADH2- 570 nmPorphyrin- 400 nm


Question: After a fast of a few days, ketone bodies become an important fuel

The brain begins to use ketone bodies when levels start to rise after 3 to 5 days of fasting. Normally, the brain will use only glucose as a fuel (most fatty acids cannot cross the blood-brain barrier to be metabolized by the brain), but when ketone bodies are elevated in the blood, they can enter the brain and be used for energy.


Question: Normal plasma osmolality is

The normal value of plasma osmolality is 285-300 mosm/kg.Osmolality is measured with an osmometer based on the depression of the freezing point of the sample.Patients with deficiency of ADH (Central diabetes insipidus) or a decreased response to ADH (Nephrogenic diabetes insipidus) will excrete urine with osmolality less than 300 mosmols/kg.Ref: D M Vasudevan 7th edition Page no: 373


Question: During starvation , muscle uses


Question: Triglycerides are transpoed from the liver to the tissues by

Synthesis of VLDL, They are synthesised in the liver from glycerol and fatty acids and incorporated into VLDL along with hepatic cholesterol, Apo-B-100, C-II and E. Apo-B-100 is the major lipoprotein present in VLDL when it is secreted. Apo-E and C-II are obtained from HDL in plasma. Metabolism of VLDL The half-life of VLDL in serum is only 1 to 3 hours. When they reach the peripheral tissues, apo-C-II activates LpL which liberates fatty acids that are taken up by adipose tissue and muscle. The remnant is now designated as IDL (intermediate density lipoprotein) and contains less of TAG and more of cholesterol. The major fraction of IDL fuher loses triglyceride, so as to be conveed to LDL (low-density lipoprotein). This conversion of VLDL to IDL and then to LDL is referred to as lipoprotein cascade pathway. A fraction of IDL is taken up by the hepatic receptors.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 153


Question: At the time of starvation body utilizes


Question: Schilling test is used to test


Question: Maximum carbohydrate concentration in strict vegetarian diet present is

(Glycogen) (21- U.Satyanarayan 3rd)GLYCOGEN - is the carbohydrate reserve in animals, hence often referred to as animal starch*** It is present in high concentration in liver, followed by muscle, brain* The enzyme hyaluronidase of semen degrades the gel (contains hyaluronic acid) around the ovum. This allows effective penetration of sperm into the ovum* Streptomycin is a glycoside employed in the treatment of T, B


Question: The enzyme used to "flush" the sticky ends of DNA is

Flushing of sticky ends means to remove the sticky ends (3' overhangs) for producing blunt-ended DNA (no overhangs). The sticky ends has 3' overhangs which can be digested with Klenow fragment (has 3'-5' exonuclease activity) to produce blunt-end DNA. Tool Role Type II restriction enzymes Cleaves DNA at specific sites DNA ligase Phosphodiester bond formation between 2 fragments Klenow fragments (DNA polymerase I without 5' to 3' exonuclease activity) Used previously for polymerization in PCR reactions Polynucleotide kinase Catalyse the transfer of g phosphate from ATP Alkaline phosphatase Removes the phosphate group from 5' end to prevent self annealing of sticky ends of DNA Reverse transcriptase RNA dependent DNA polymerase for cDNA synthesis RNAase H Removes RNA from DNA-RNA hybrid Exonuclease III Removes nucleotide from 3' end Phage g exonuclease Removes nucleotide from 5' end Terminal nucleotidyl transferase In homopolymer tailing to conve blind end to sticky end


Question: RNA with Enzymatic activity is

Interestingly, some RNA molecules have intrinsic catalytic activity. The activity of these RNA enzymes, or ribozymes, often involves the cleavage of a nucleic acid. Two ribozymes are the peptidyl transferase that catalyzes peptide bond formation on the ribosome, and ribozymes involved in the RNA splicing.Ref: Harper&;s; 30th edition; Page no: 363


Question: Site of maximum absortion of Iron

Mnemonic
Iron - Roman number One
So maximum absorption in first part of small intestine. i.e: Duodenum.


Question: The term restriction map primarily refers to the mapping of sites of

Restriction map of DNA mapping of sites of cleavage of restriction enzymes on a DNA fragment. Identifies fragments of DNA that contain specific genes or sequences. Example of a restriction map of bacteriophage DNA


Question: In DNA, Adenine pairs with

Adenine is always paired with thymine by formation of two hydrogen bonds. Guanine is always paired with cytosine by formation of three hydrogen bonds.


Question: The main enzyme responsible for activation of xenobiotics is (detoxification)


Question: Human insulin gene receptor found on chromosome

The insulin gene is located in the sho arm of chromosome 11 in humans in the region p13-->pter


Question: Rate limiting enzyme in testosterone synthesis

Cholesterol is first acted upon by desmolase and a 6-carbon unit is cleaved off, forming 21 carbon steroid, pregnenolone It is the common precursor for all the steroid hormonesRef: DM Vasudevan, 7th edition, page no: 664


Question: Fluorescamine is used to detect

Fluorescence detectors are generally more sensitive than photometric ones. In addition, precolumn or postcolumn reactors have been used to chemically tag a compound with a fluorescent label for subsequent detection. For example, amino acids and other primary amines often are labeled with a dansyl or fluorescamine tag, followed by HPLC separation and fluorometric detection. Ref: Tietz Textbook of Clinical Chemistry and Molecular Diagnostics, 5E Page no. 319 Topic : Fluorometers.


Question: Jumping genes are also known as

Transposons are called as Jumping genes as they can jump from one chromosome locus to another.


Question: DNA supercoiling is done by

Enzymes that catalyze topologic changes of DNA are called topoisomerases. Topoisomerases can relax or inse supercoils, using ATP as an energy source. DNA gyrase is a type of topoisomerase Harper30e pg: 362


Question: Micro RNA transcribed by

RNA polymerase II (also called RNAP IIand Pol II) is an enzyme found in eukaryotic cells. It catalyzes the transcription of DNA to synthesize precursors of mRNA and most snRNA and microRNAIn eukaryote cells, RNA polymerase III(also called Pol III) transcribes DNA to synthesize ribosomal 5S rRNA, tRNA, and other small RNAs.RNA polymerase 1 (also known as Pol I) is, in higher eukaryotes, the polymerase that only transcribes ribosomal RNA (but not 5S rRNA, which is synthesized by RNA polymerase III), a type of RNA that accounts for over 50% of the total RNA synthesized in a cellThe DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule.


Question: Synthesis of secretory proteins takes place in

Secretory proteins are synthesized in EPR Reference: Harper; 30th edition

First in endoplasmic reticulum then in cytoplasm


Question: Ketone bodies utilized by conversion of

(C) Acetoacetate to ... # Ketone bodies (Acetoacetate and 3-Hydroxybutyrate) serve as a fuel for extrahepatic tissues> Liver forms ketone bodies but cannot utilize it.


Question: Hartnup's disease is associated with disturbed metabolism of

(C) Tryptophan # HARTNUP DISEASE:> This disorder is characterized by reduced intestinal absorption & renal reabsorption of neutral amino acids.> The defect involves an amino acid transporter on the brush border of the jejunum & the proximal tubule. Intestinal absorption of free amino acids is reduced, though the neutral amino acids can be absorbed when present in di- & tripeptides.> Degradation of unabsorbed tryptophan by intestinal bacteria produces indolic acids that are absorbed & subsequently excreled at high levels in the urine of these patients.> The disorder is inherited as an autosomal recessive trait with an estimated incidence of 1 in 24,000 live births. Linkage analysis suggests a locus on chromosome 5.


Question: Method of choice for protein identification

While the requisite amino acid sequence information can be obtained using the Edman technique, today mass spectrometry (MS) has emerged as the method of choice for protein identification.
Ref: Harper’s illustrated biochemistry. 30th edition page no: 30


Question: Iodine gives red colour with

Amylose: Gives blue with iodine testAmylopectin: Gives reddish violet with iodine testGlycogen: With iodine-: deep red colour


Question: Translocation is necessary for

tRNA fixed at the p site does not carry any amino acid and is therefore released from the ribosomeThen the whole ribosome moves over mRNA through the distance of one codon. The peptidyl tRNA is translocated to the P Site; this done with the help of elongation factor 2Translocation requires hydrolysis of GTP TO GDPRef: DM Vasudevan, 7th edition, page no: 601, 602


Question: Selenocysteine is similar to

Selenocysteine is similar to cysteine. Selenocysteine arises co-translationally during its incorporation into peptides. The UGA anticodon of the unusual tRNA designated tRNAsec normally signals to STOP. The ability of the protein synthesizing apparatus to identify a selenocysteine-specific UGA codon involves the selenocysteine inseion element, a stem-loop structure in the untranslated region of the m-RNA. Selenocysteine-tRNAsec is first charged with serine by the Ligase that charges tRNAsec. Subsequent replacement of the serine oxygen by selenium involves seleno- phosphate formed by Selenophosphate synthetase.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 80


Question: Ends of chromosomes replicated by

Telomerase is responsible for synthesis of and maintenance of telomere length (end of chromosome).


Question: Function of mitochondrial DNA

Mitochondria contains specific DNA .The integral inner membrane proteins ,are made by mitochondrial protein synthesizing machinery. However, the majority of proteins,especially of outer membrane are synthesized under the control of cellular DNA. The division of mitochondria is under the command of mitochondrial DNA. REF :DM VASUDEVAN TEXTBOOK ; 7thEDITION ;PAGE NO :13


Question: Type of collagen found in space of Disse in liver is

Type III is seen in skin, lung and vascular tissues Type IV is seen in the basement membranes. About 30 genes are resposible for the collagen synthesis, and the enzymes necessary for collagen synthesis REFERENCE : DM VASUDEVAN TEXTBOOK SEVENTH EDITION : PAGE NO :720


Question: First substrate of Kreb's cycle is

Ans. is 'a' i.e. Pyruvate The Kreb's cycle or citric acid cycle or tricarboxylic acid cycle is the final common pathway for the aerobic oxidation of carbohydrate, lipid and protein because glucose, fatty acids and most amino acids are metabolised to acetyl-CoA or intermediates of the cycle.The first reaction of the citric acid cycle is the condensation of acetyl-CoA with oxaloacetate to form citrate, catalyzed by citrate synthase. Oxalo-acetate is the first substrate of citrate synthase, it binds to the enzyme and induces a large conformational change in the flexible domain, creating a binding site for the second substrate, acetyl CoA.Thus the answer should be oxalo-acetate. Since it was not amongst the option, the best option is Pyruvate. Pyruvate formed at the end of glycolysis is taken up into mitochondria where it is converted to acetyl-CoA.


Question: Pasteur effect is

Inhibition of glycolysis due to absence of oxygen


Question: Dietary triglycerides are transported by

Ans. is 'a' i.e., Chylomicron : Chief carrier of exogenous TGs (dietary TGs) is -Chylomicrons*Chief carrier of endogenous TGs (i.e.,., synthesized in the liver) - VLDL*Circulation of lipids in the bodyLipid being insoluble (hydrophobic) cannot be transported in blood. So they are associated with 'polar' substances to form hydrophilic lipoprotein complexes 'Classification of lipoprotein on the basis of hydrated density: (As the proportion of lipids to protein decreases, the density of the lipoprotein complex increases)Chylomicrons lowest density*, highest content of lipids(TGs)*IDL (Intermediate density lipoproteins)LDL (low density lipoproteins)HDL (High density lipoproteins)After fat digestion, absorbed fatty acids are reesterified to form TGs and these TGs are converted to lipoprotein complex chylomicrons. These chylomicrons pass to blood circulation through the lymphatic ducts. In the capillaries, lipoprotein lipase (present on the surface of the endothelium) acts on the chylomicrons and removes most of the TGs from the chylomicrons Chylomicrons are thus converted into chylomicron remnants (CRs). There CRs are taken up by the liver.VLDLs are found in the liver and transport TGs formed in the liver to the extrahepatic tissues. In the blood capillaries, LPL acts on the YLDL and removes TGs from it. Thus VLDL is converted to IDL.Most of the IDL particles change into LDL (by losing their apoE and some of TGs). Some of IDL is taken up by liver and also the peripheral tissues.Most of LDL particles deliver the cholesterol to the extrahepatic tissues. Only some of the remaining LDL particles are taken up by the liver cells.HDL, is synthesized in the liver cells and removes cholesterol from the extrahepatic tissue and transfers it to the liver.So RememberMaximum exogenous TGs is seen in - Chylomicrons *Maximum endogenous TGs is seen in - VLDL* Maximum TGs is seen in - Chylomicrons*Maximum cholesterol is seen in - LDL*Cholesterol is transported from liver mainly as - VLDL*Carrier of cholesterol in plasma - LDL*Dietary cholesterol is transported to the extrahepatic tissues by - LDL*Cholesterol is transported from the extrahepatic tissues to the liver HDL*


Question: Thiamine deficiency causes decreased energy production because

thiamine deficiency causes a decrease in energy production because it acts as a coenzyme in many energy producing processes Thiamine generally function in the decarboxylation reaction of alpha-keto acids and branched chain amino acids Pyruvate Dehydrogenase which conves Pyruvate to Acetyl CoA aKetoGlutarate dehydrogenase in Citric Acid Cycle which conves a KetoGlutarate to Succinyl CoA Branched Chain Ketoacid dehydrogenase which catalyses the oxidative decarboxylation of Branched Chain Amino acids Trans Ketolase in the Pentose Phosphate Pathway. This is the biochemical basis of assay of Thiamine status of the body ref DM Vasudevan 8th ed page 467

It is required for the process of transamination

It is co-fact or for oxidative reduction

It is co-enzyme for transketolase in pentose phosphate pathway

It is co-enzyme for pyruvate dehydrogenase and a- ketoglutarate dehydrogenase in Tricarboxylic acid pathway


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

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


Question:
The assembly of secondary structural units into larger functional units such as the mature
polypeptide and its component domains is

The modular nature of protein synthesis and folding are embodied in the concept of orders of protein structure:

Primary structure—the sequence of amino acids in a polypeptide chain
Secondary structure—the folding of short (3-30 residue), contiguous segments of polypeptide into geometrically ordered units.
Tertiary structure—the assembly of secondary structural units into larger functional units such as the mature polypeptide and its component domains.
Quaternary structure—the number and types of polypeptide units of oligomeric proteins and their spatial arrangement.

Ref: Harper’s illustrated biochemistry. 30th edition page no: 37


Question: In the upright position, from apex to base of the lung

Ventilation, as well as perfusion in the upright position, declines in a linear fashion from the bases to the apices of the lungs.

Ventilation decreases, perfusion decreases

Ventilation decreases, perfusion increases

Ventilation increases, perfusion increases

Ventilation increases, perfusion decreases


Question: Proteins are stored by

Golgi-apparatus is involved in O-glycosylation and processing of oligosaccharide chains of membrane and other N-linked glycoproteins and trans-golgi apparatus is involved in sorting of various proteins prior to their delivery to appropriate intracellular destination.


Question: Alpha helix and beta pleated sheet is seen in

Secondary Structure: The peptide chain formed assumes a three-dimensional secondary structure by way of folding or coiling consisting of a helically-coiled, zigzag, linear or mixed form. It results from the steric relationship between amino acids located relatively near each other in the peptide chain. The linkages or bonds involved in the secondary structure formation are hydrogen bonds and disulfide bonds. Can be alpha helix or beta pleated structures.Ref: Textbook of medical biochemistry, MN Chatterji, 8th edition, page no: 89


Question: Codon does not have

Twenty different amino acids are required for the synthesis of the cellular complement of proteins; thus, there must be at least 20 distinct codons that make up the genetic code. Since there are only four different nucleotides in mRNA, each codon must consist of more than a single purine or pyrimidine nucleotide. Codons consisting of two nucleotides each could provide for only 16(42 )-distinct codons, whereas codons of three nucleotides could provide 64(43 )-specific codons. It is now known that each codon consists of a sequence of three nucleotides; that is, it is a triplet code. The terms first, second, and third nucleotide refer to the individual nucleotides of a triplet codon read 5'-3', left to right. A adenine nucleotide; C, cytosine nucleotide; G, guanine nucleotide; Term, chain terminator codon; U, uridine nucleotide. AUG, which codes for Met, serves as the initiator codon in mammalian cells and also encodes for internal methionines in a protein. Thus codon does not have thymine.Ref: Harpers Illustrated Biochemistry, 30th edition, page no: 414


Question: Glucose transporters present in the β cells of the Islets of Langherhans is


Question: In a seriously ill patient, addition of amino acids in the diet results in a positive nitrogen balance. The mechanism for this is

Glucose, mannose, aminoacids (such as leucine, arginine, others) and β ketoacids such as acetoacetate (derived from fat catabolism) stimulate insulin secretin and have protein sparing effect.
Insulin has anabolic effect on metabolism. It decreases protein catabolism and fat catabolism for energy production and increases aminoacid uptake and protein synthesis (positive nitrogen balance).

Increased absorption of amino acids from the intestine


Question: Aggrecan in

Aggrecan is the major proteoglycan component of cartilage. It is composed of several glycosaminoglycans (hyaluronic acid, chondroitin sulfate and keratin sulfate) and both link and core proteins.


Question: Biotechnology is/are used for

Biotechnology is the use of living systems and organisms to develop or make products, or "any technological application that uses biological systems, living organisms or derivatives thereof, to make or modify products or processes for specific use


Question: Mitochondrial membrance protein contain transpoer of

The electron transpo chain in the mitochondrial membrane has been separated in 4 (four) complexes or components as follows: Complex I: NADH-CoQ reductaseComplex II: Succinate-CoQ reductase Complex III: CoQ-cytochrome C reductase Complex IV: Cytochrome C oxidaseRef: MN Chatterjea Textbook of Medical Biochemistry, 8th Edition, Page no: 139


Question: Proper functioning of Kreb cycle does not occur with deficiency of

Biological active form is Thiamine pyrophosphate (TPP). Acts as a coenzyme in several metabolic reactions. * Acts as coenzyme to the enzyme pyruvate dehydrogenase complex (PDH) which conves pyruvic acid to acetyl-CoA (oxidative decarboxylation) Pyruvate PDH TPP Acetyl-CoA * Similarly acts as a coenzyme to a-oxoglutarate dehydrogenase complex and conves a-oxoglutarate to succinyl-CoA (oxidative decarboxylation). a-oxoglutarate dehydrogenase a-Oxoglutarate TPP Succinyl-CoARef: MN Chatterjea Textbook of Medical Biochemistry, 6th Edition, Page no: 178


Question: Aminoacid that enters the TCA cycle for gluconeogenesis & Ketogenic in nature

Phenylalanine is both glucogenic (gluconeogenic) and ketogenic.


Question: The two nitrogen atoms that are incorporated into the urea cycle. The source of the nitrogen is

Two nitrogen atoms of urea are derived from two different sources, one from ammonia and the other directly from alpha amino group of aspaic acid.Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 203


Question: The primary structure of a protein refers to

The linear sequence of amino acid residues and location of disulphide bridges, if any, in a polypeptide constitute its primary structure.

Linear structure and order of the amino acids present

Regular confirmational forms of a protein

Complete three-dimensional structure of the polypeptide units of a given protein


Question: Immediate precursor of creatine

Creatine constitutes about 0.5% of total muscle weight.It is synthesized from 3 aminoacids, glycine,arginine and methionine. STEP 1 :In the first reaction the amidino group of arginine is transferred to glycine to form guanidoacetic acid,catalysed by amido transferase. STEP 2 :Guanidoacetic acid is methylated by S-adenosyl methionine (SAM) bt methyl transferase to form creatine. STEP 3 :Creatine is phosphorlated to creatine phosphate.The reaction needs hydrolysis of ATP. STEP 4 :The creatine phophate may be conveed to its anhydride, creatinine.It is a non-enzymatic spontaneous reaction. REF :DM VASUDEVAN TEXTBOOK ;7th EDITION ; Page no :211


Question: Eicosanoids are derived from

EICOSANOIDSThey are 20 C compounds (Greek, eikosi = twenty), derived from arachidonic acid. Their names are:1. Prostanoids, containing1-a. Prostaglandins (PGs);1-b. Prostacyclins (PGIs);1-c. Thromboxanes (TXs)2. Leukotrienes (LTs)Ref: DM Vasudevan - Textbook of Biochemistry, 6th edition, page no: 163


Question: RNA with ENZYMATIC ACTIVITY

In addition to the catalytic action served by the snRNAs in the formation of mRNA, several other enzymatic functions have been attributed to RNA. Ribozymes are RNA molecules with catalytic activity. These generally involve transesterification reactions, and most are concerned with RNA metabolism (splicing and endoribonuclease). Recently, a rRNA component has been implicated in hydrolyzing an aminoacyl ester and thus to play a central role in peptide bond function (peptidyl transferases). These observations, made using RNA molecules derived from the organelles from plants, yeast, viruses, and higher eukaryotic cells, show that RNA can act as an enzyme, and have revolutionized thinking about enzyme action and the origin of life itself.


Question: Enzyme causing covalent bond cleavage without hydrolysis

These enzymes can remove groups from substrates or break bonds by mechanisms other than hydrolysis. For example, Fructose-1,6-bisphosphate -------- Glyceraldehyde-3-phosphate +dihydroxy acetone phosphateRef: DM Vasudevan, Page no: 41


Question: An example of scleroprotein is

Scleroproteins: They are insoluble in water, salt solutions and organic solvents and soluble only in hot strong acids. They form supporting tissues, e.g. collagen of bone, cartilage and tendon; keratin of hair, horn, nail and hoof. Keratin is one of the examples.
Reference: Vasudevan 7th  ed, pg 43


Question: Inulin is a polymer of


Question: Precursor of norepinephrine

Catecholamines are derived from tyrosine.They are so named because of the presence of catechol nucleus.They include epinephrine, norepinephrine and dopamine.They are produced by the adrenal medulla and sympathetic ganglia. Tyrosine is first hydroxylated to DOPA by tyrosine hydroxylase. Dopamine is fuher hydroxylated to norepinephrine or noradrenaline.The term "nor" denotes that the molecule does not contain the "R" or methyl group. REFERENCE : DM.VASUDEVAN.TEXTBOOK SEVENTH EDITION;page the : 234 and 235.


Question: The power house of the cell is

Aerobic organisms are able to capture a far greater propoion of the available free energy of respiratory substrates than anaerobic organisms. Most of this takes place inside mitochondria, which have been termed the "powerhouses" of the cell. Respiration is coupled to the generation of the high-energy intermediate, ATP, by oxidative phosphorylation.Ref: Harper&;s Biochemistry; 30th edition; Chapter 13; The Respiratory Chain & Oxidative Phosphorylation


Question: Von Gierke's occurs due to deficiency of

Glucose - 6- phosphatase is deficient in Von Gierke's disease.


Question: Bovine milk contains


Question: DNA fragments formed by restriction enzymes are separated by

Agarose is the supp medium for the gel electrophoresis it is viscous liquid when hot but solidify to a gel on cooling.The gel is prepared in the buffer and spread over microscopic slides and allowed to cool.A small sample of serum or the biological fluid is applid by cutting into the gel with a sharp edge.The electrophoretic run takes about 90 minutes.This technique is modified for immunoelectrophoresis.Agarose gel is used as suppo to seperate different types of protein mixtures as well as nucleic acids. REFERENCE: DM VASUDEVAN TEXTBOOK SEVENTH EDITION Page no:447


Question: Selenocysteine is synthesized from

Selenocysteine is the 21st amino acid. Biosynthesis of Selenocysteine is by replacing the oxygen by selenium in Serine which in turn formed from Cysteine.Ref: DM Vasudevan - Textbook of Biochemistry, 7th edition, page no: 214


Question: Role of somatomedin in fat metabolism

Antilipolytic

Like insulin, somatomedin (also called insulin-like growth factor) has antilipolytic effect.


Question: Diagnosis of vitamin B1 deficiency is made by

Diagnosis of Vit B1 deficiency is made by Transketolase activity.Biochemical Parameters In thiamine deficiency, blood thiamine is reduced, but pyruvate, alpha-ketoglutarate and lactate are increased. Erythrocyte transketolase activity is reduced; this is the earliest manifestation seen even before clinical disturbances.Reference: Textbook of Biochemistry by D M Vasudevan, sixth edition pg no. 392


Question: Following clinical manifestation is a feature of

Image showing Trichorrhexis nodosa. Argininosuccinic aciduria, accompanied by elevated levels of argininosuccinate in blood, cerebrospinal fluid, and urine, is associated with friable, tufted hair (trichorrhexis nodosa). It is due to the deficiency of the enzyme argininosuccinate lyase. Reference: Harpers illustrated biochemistry 30th edition


Question: Following Vitamin Prevents Peroxidation of lipids of cellular level

Vitamin E is the most powerful natural antioxidant. Free radicals are continuously being generated in living systems. Their prompt inactivation is of great impoance. Vitamin E is a known biological antioxidant able to quench the lipid peroxidation chain and to protect the plasma membranes from the attack of free radicals. Vitamin E protects RBC from hemolysis. By preventing the peroxidation, it keeps the structural and functional integrity of all cells. It protects the polyunsaturated fatty acids (PUFA) from peroxidation reactions. Vitamin E acts as a scavenger and gets itself oxidized (to quinone form) by free radicals (R) and spares PUFA Gradual deterioration of the ageing process is due to the cumulative effects of free radicals. Vitamin E also boosts the immune response Ref: DM Vasudevan - Textbook of Biochemistry, 8th edition, page no: 461


Question: Compound that joins glycolysis with glycogenesis and glycogenolysis is

Glucose-6-phosphate is an important compound that joins several metabolic pathways viz. glycolysis, glycogenolysis, glycogenesis, gluconeogenesis and pentose phosphate pathway.