英文习题总汇

Structure and Function of Protein

Multiple choice questions:

1.An amion acid having no asymmetric carbin atom is A. Alanine B.Leucine C.Glycine D.Arginine 2.An amino having two asymmetric carbon atoms is A.Glycine B.Cysyeine C.Valine D.Threonine

3.Glutathione is a

A.Decapeptide B.Octapeptide C.Pentapeptide D.Tripeptide 4.At isoeletric pH, an amino acid exists as

A.Anion B.Cation C.Zwitterion D.None of the above 5.Primary structure of a protein is broken by

A.Heat B.Ammonium C.Pepsin D.All of the above 6.Quaternary structure is present in

A.Coagulated protein B.Denatured protein C.Haemoglobin D.Myoglobin

7.α-Helix is formed by

A.Hydrogen bonds B.Hydrophobic bonds C.Disulphide bonds D.All of the above Essay Questions:

1. How is a peptide bond formed? What are the characterdistic of a peptide bond?

2. Describe the primary,secondary and tertiary structures of proteind. What are the forces, which stabilise them?

3. Explain the structural organisation of haemoglobin molecule. How dose the alteration in amino acid sequence affect the properties of haemoglobin?

Enzyme

Multiple Choice Questions 1.Coenzymes combine with:

A.Proenzyme B.Apoenzyme C.Holoenzymes D.Antienzymes 2.Coenzymes are required in the following reactions: A.Oxidation-reduction B.Transamination C.Phosphorylation D.All of the above

3.The following coenzyme takes part in hydrogen transfer reactions: A.Tetrahydrofolate B.Coenzyme A C.Coenzyme Q D.Biotin 4.A coenzyme required in transamination reactions is:

A.Coenzyme A B.Coenzyme Q C.Biotin D.Pyridoxal phosphate 5.Coenzyme A contains a vitamin which is:

A.Thiamin B.Ascorbic acid C.Pantothenic acid D.Niacinamide 6.A coenzyme required in carboxylation reaction is:

A.Lipoic acid B.Coenzyme A C.Biotin D.All of the above 7.When the substrate concentration equals Km in an enzyme-catalysed reaction:

A.Afew of the enzyme molecules are present as ES complex B.Majority of the enzyme molecules are present as ES complex C.Half of the enzyme molecules are present as ES complex D.All the enzyme molecules are present as ES complex 8.In Lineweaver-Burk plot, the y-intercept represents: A.Vmax B.1/Vmax C.Km D.1/Km

9. 8.In Lineweaver-Burk plot, the x-intercept represents:

A.Vmax B.Km C.Reciprocal of Vmax D.Reciprocal of Km 10.In competitive inhibition, the inhibitor:

A.Competes with the enzyme B.Irreversibly binds with the enzyme C.Binds with the substrate D.Competes with the substrate 11.Competitive inhibitors:

A.Decrease the Km B.Decrease the Vmax C.Increase the Km D.Increase the Vmax

12.Competitive inhibition can be relieved by raising the: A.Enzyme concentration B.Substrate concentration C.Inhibitor concentration D.None of the above 13.Allopurinol is a competitive inhibitor of:

A.Dihydrofolate reductase B.Xanthine oxidase C.Carbonic anhydrase D.Acetylcholinesterase 14.Non-competitive inhibitors:

A.Increase the Km B.Increase the Vmax C.Decrease the Km D.Decrease the Vmax

15.Inactive precursors of enzymes are known as:

A.Apoenzyme B.Coenzyme C.Proenzyme D.Holeenzyme 16.In case of enzymes regulated by covalent modification, addition of phosphate to the enzyme coverts: A.Inactive enzyme into active enzyme B.Active enzyme into inactive enzyme C.Either A or B D.Neither A nor B

17.Lactate dehydrogenase is a:

A.Monomer B.Dimer C.Tetramer D.Hexmaer Essay Questions:

1.What are the salient feature of the active site of the enzyme?

2.Explain in detail the factors affecting the velocity of an enzyme reaction.

3.What is the competitive inhibition? Explain with an example of its therapeutic significance.

4.What is meant by Km value, and what is its significance?

Structure and Function of Nucleic Acid

Multiple choice questions:

1.A nitrogenous base that does not occur in mRNA is

A.Cytosine B.Thymine C.Uracil D.All of the above 2.In nucleotides, phosphste is attached to sugar by

A.Salt bond B.Hydrogen bond C.Ester bond D.Glycosidic bond 3.In DNA, the complementary base of adenine is A.Guanine B.Cytosine C.Uracil D.Thymine 4.In DNA, three hydrogen bonds are formed between A.Adenine and guanine B.Adenine and thymine C.Guanine and cytosine D.Thymine and cytosine 5.The pyrimidine base in RNA are

A.Cytosine and uracil B.Cytosine and thymine C.Thymine and uracil D.Any of these pairs

6.7-Methylguanosine triphosphate cap is present at the A.5＇-End of tRNA B.3＇-End of tRNA C.5＇-End of mRNA D.3＇-End of mRNA

7.Heterogeneous nuclear RNA is the precursor of

A.mRNA B.tRNA C.rRNA D.All of the above 8.A purine base si present in all the following coenzymes except A.NAD B.NADP C.FMN D.FAD

9.The number of hydrogen bonds between adenine and thymine in DNA is A.1 B.2 C.3 D.4 Essay Questions:

1.Dsecribe the structure of DNA. What are the differences between DNA and RNA?

2.Wha are the salient feature of Watson-Creak model of DNA? 3.Describe different types of RNA.

Metabolism of Carbohydrates

Multiple choice questions:

1.Glycolytic pathway is located in:

A.Mitochondria B.Cytosol C.Microsome D.Nucleus 2.Glucokinase is found in:

A.Muscles B.Brain C.Liver D.All of the above

3.The reaction catalysed by the following enzyme is freely reversible: A.Hexokinase B.Phosphohexose isomerase C.Pyruvate kinase D.Phosphofructokinase 4.The following is an allosteric enzyme:

A.Phosphohexose isomerase B.Phosphotriose isomerase C.:Lactate dehydrogenase D.Phosphofructokinase 5.Glycolysis is not an allosteric in:

A.Liver B.Brain C.Kidneys D.Erythrocytes 6.ATP is a co-substrate as well as an allosteric inhibitor of: A.Phosphofructokinase B.Hexokinase C.Glucokinase D. None of the above

7.Pyruate kinase is inhibited by:

A.Enol pyruate B.Lactete C.Citrate D. Alanine

8.Complete oxidation of one molecule of glucose into CO2 and H2O yields:

A.8 ATP equivalents B. 15 ATP equivalents

C. 30 ATP equivalents D. 38 ATP equivalents

9.The number of NADP molecules reduced per molecule of glucose-6-phosphate converted into ribulose-5-phosphate is: A.One B.Two C.Six D.Twelve 10.Glycogenesis requires:

A.GTP B.CTP C.UTP D.None of the above 11.Substrate for glycogen synthetase are glycogen primer and: A.Glucose B.UDP-Glucose

C.Glucose-phosphate D.Glucose-6-phosphate 12.Glycogen synthetase catalyses the formation of: A.α-1,4-Glycosidic bonds B.α-1,6-Glycosidic bonds

C.Both of the above D.Neither of the above

13.The energy spent for addition of each glucose unit to the glycogen primer is:

A.One ATP equibalent B.Two ATP equibalents C.Three ATP equibalents D.Four ATP equibalents 14.Glycogenesis is increased by:

A.Glucagon B.Insulin C.Epinephrine D.cAMP 15.Glycogen phosphorylase hydrolyses:

A.α-1,6-Glycosidic bonds B.α-1,4-Glycosidic bonds

C.β-1,4-Glycosidic bonds D.All of the above

16.Glucose-1-phosphate liberated from glycogen cannot be converted into free glucose in:

A.Liver B.Kidney C.Muscles D.Brain

17.Generally glycogenolysis in muscles immediately followed by:

A.Glycolysis B.Gluconeogenesis C.HMP shunt D.Lipogenesis 18.If glucose-1-phosphate formed by glycogenolysis in muscles is catabolised to lactate, the energy yield will be: A.2 ATP equivalents B. 3 ATP equivalents C. 4 ATP equivalents D. 8 ATP equivalents 19.Cyclic AMP is binds to:

A.Catalytic subunits of protein kinase A B.Regulatory subunits of protein kinase A C. Catalytic subunits of phosphorylase kinase D. Regulatory subunits of phosphorylase kinase 20.Glucose is the only source of energy for:

A.Myocardium B.Kidneys C.Erythrocytes D.Thrombocytes

21.Glycerol-3-phosphate for the synthesis of triglycerides in adipose tissue is derived from:

A.Phosphatidic acid B.Diacylglycerol C.Glycerol D.Glucose 22.Gluconeogenesis occurs in:

A.Adipose tissue B.Muscles C.Kidneys D.Brain 23.Reactions of gluconeogenesis occur in:

A.Cytosol only B.Mitochondria only

C.Cytosol and mitochondria D. Cytosol and microsomes 24.A gluconeogenic enzyme among the following is: A.Phosphofructokinase B.Pyruvate kinase

C.Phosphoenol pyruvate carboxykinase D.Glucokinase 25.Gluconeogenesis is decreased by:

A.Glucagon B.Epinephrine C.Glucocorticoids D.Insulin 26.Glucose-6-phosphatase is not present in: A.Liver and kidneys B.Kidneys and muscles

C.Kidneys and adipose tissue D.Muscles and adipose tissue

27.Fructose-1,6-biphosphatase is regulated by:

A.Induction B.Repeession C.Allosteric regulation D.All of the above 28.Fructose-2,6- biphosphatase is an allosteric regulator of: A.Phosphofructokinase B. Fructose-1,6- biphosphatase C.Both of the above D.Neither of the above 29.Glycogenesis requires:

A.Uridine diphosphate glucose B.Glycogen synthetase C.Branching Enzyme D.All of the above 30.GTP is required in the reation catalysed by: A.Pyruvate carboxylase B.PEP carboxykinase

C.Fructose-1,6-biphosphatase D.Glucose-6-phosphatase

31.Cori cycle transfers:

A.Glucose from muscles to liver B.Lactate from muscles to liver C.Lactate from liver to muscles D.Pyruvate from liver to muscles 32.Glucogenin is:

A.Uncoupler of oxidative phosphorylation B.Polymer of glycogen molecules

C.Protein primer for glycogen synthesis D.Intermediate in glycogen breakdown 33.ATP is converted into ADP in reactions catalysed by: A.Hexokinase and pyrubate kinase

B.Phosphofructokinase and phosphoglycerate kinase C.Hexokinase and phosphofructokinase

D.Phosphoglycerate kinase and pyruvate kinase 34.ADP is converted into ATP in reactions catalysed by: A.Hexokinase and pyrubate kinase

B.Phosphofructokinase and phosphoglycerate kinase C.Hexokinase and phosphofructokinase

D.Phosphoglycerate kinase and pyruvate kinase

35.Energy is capturede in the following phase of glycolysis: A.Glucose→→Fructose-1,6-biphosphate

B.Fructose-1,6-biphosphate→Glyceraldehyde-3-phosphate Dihydroxyacetone phosphate

C.Glyceraldehyde-3-phosphate→→Pyrubate

D.All of the above

36.The correct sequence of intermediates in glycolysis is:

A.1,3-Biphosphoglycerate→3-Phosphoglycerate→2-Phosphoglycerate→Phos phoenolpyrubate

B.1,3-Biphosphoglycerate→2-Phosphoglycerate→3-Phosphoglycerate→Phos phoenolpyruvate

C.1,3-Biophosphoglycerate→Phosphoenolpyruvate→2-Phosphoglycerate→3- Phosphoglycerate

D.Phosphoenolpyruvate→1,3-Biphosphoglycerate→3-Phosphoglycerate→2- Phosphoglycerate

37.The regulatory enzyme in glycogenesis is:

A.UDP-Glucose pyrophosphorylase B.Glycogen synthetase C.Branching enzyme

D.All of the above

38.The regulatory enzyme in glycogenolysis is:

A.Phosphorylase B.Glucan transferase C.Debranching enzyme D.Glucose-6-phosphatase 39.Gluconeogenic enzymes:

A.Circumbent the energy barriers in glycolysis B.Are present in mitochondria C.Catalyse endergonic

D.Are regulated by covalent modification

40.In human beings, phosphoenolpyruvate carboxykinase is present in:

A.Cytosol B.Mitochondria C.Both of the above D.Neither of the above 41.All the following statements about intestinal glucose absorption are correct except:

A.It is absorbed against its concentration gradient

B.Rate of its absorption is proportional to sodium gradient C.Its active absorption is enhanced by insulin

D.Energy is speng during active uptake of glucose to expel sodium ions 42.A coenzyme required by transketolase as well as pyrubate dehydrogenase complex is:

A.Thiamin pyrophosphate B.Lipoic acid C.FAD D.NAD 43.All the following statements about fructokinase are correct except: A.It is present in liver B.It has a low Km for fructose

C.It converts fructose into fructose-6-phosphate D.Its activity is not affected by insulin

Answers:

1.B 2.C 3.B 4.D 5.D 6.A 7.D 8.C 9.B 10.C 11.B 12. A 13.B 14.B 15.B 16.C 17.A 18.B 19.B 20.C 21.D 22.C 23.C 24.C 25.D 26.D 27.D 28.A 29.D 30.B 31.B 32.C 33.C 34.D 35.C 36.A 37.B 38.A 39.A 40.C 41.C 42.A 43.C Questions:

1.What is the major catabolic pathway of glucose under anaerobic conditions? Mention the steps in the pathway and indicate the key enzymes. 2.What are the irreversible glycolysis?

3.”Gluconeogenesis is not a simple reversal of glycolysis”; justify your answer by giving the reations.

Biological Oxidation

Multiple choices questions:

1.A high-energy phosphate amongst the following is: A.Glucose-6-phosphate B. Glucose-1-phosphate C.1,3-Biphosphoglycerate D.All of the above

2.ADP can receive a phosphate group from:

A.Fructose-6-phosphate B.Glycerol-3-phosphate C.Creatine phosphate D.None of the above

3.The compound having the highest redox potential amongst the following is: A.Coenzyme Q B.NAD C.Cytochrome c D.Cytochrome b 4.Cytochrome oxidase is poisoned by all the following expect:

A.Carbon monoxide B.Hydrogen sulphide C.Oligonycin D.Cyanide 5.Iron-porphyrin is present as prosthetic group in:

A.Cytochromes B.Catalase C.Peroxidase D.All of the above

6.A copper-containing cytochrome is: A.Cytochrome a B.Cytochrome b

C.Cytochrome a3 D.None of the above

7.When reducing equivalents enter the respiratory chain through NAD, the P:O is:

A.1:2 B.2:1 C.1:2.5 D.2.5:1

8.Rate of tissue respiration is raised when the intracellular concentration of: A.ADP increases B.ATP increases C.ADP decreased D.None of the above

9.In some reactions, energy is captured in the form of: A.GTP B.UTP C.CTP D.None of the above

10.Substrate-linked phosphorylation occurs in:

A.Glycolytic pathway B.Citric acid cycle C.Both of the above D.Neither of the above

11.Reducing equivalents move in the respiratory chain from: A.Relatively electronegative to electropositive components B.Lower redox potential to higher redox potential C.Reduced substrate to oxygen D.All of the above

12.Hydrogen peroxide may be detoxified in the absence of an oxygen acceptor by:

A.Peroxidase B.Catalase C.Both of the above D.Neither of the above 13.All the following statements about hepatic microsomal hydroxylase system

are correct except:

A.It metabolises several drugs B.It contains cytochrome P-450 C.It contains a flavoprotein D.It contains iron-sulphur protein 14.Superoxide radicals can be detoxified by:

A.Cytochrome C B.Superoxide dismutase C.Both of the above D.Neither of the above Answers:

1.C 2.C 3.C 4.C 5.D 6.C 7.D 8.A 9.A 10.C 11.D 12.B 13.D 14.C Questions:

1.Write the member of the Electron transport chain, in the order of redox potentials, and show the steps where ATP is synthesized. 2.Define oxidative phosphorylation.

Metabolism of Lipid

Multiple choices questions:

1.Acyl carrier protein contains the vitamin:

A.Biotin B.Lipoic C.Pantothenic acid D.Folic acid

2.The following is required as a reductant in in fatty acid synthesis: A.NADH B.NADPH C.FADH2 D.FMNH2

3.De nove synthesis of fatty acid requires all of the following except: A.Biotin B.NADH C.Pantothenic acid D.ATP

4.β-Oxidation of fatty acids requires all the following coenzymes except: A.CoA B.FAD C.NAD D.NADP 5.Propionyl CoA is formed on oxidation of:

A.Monounsaturated fatty acid B.Polyunsatrated fatty acid

C.Fatty acids with odd number of carbon atoms D.None of the above 6.An enzyme required for the synthesis of ketone bodies as well as choleseterol is:

A.Acetyl CoA carboxylase B.HMG CoA synthetase

C.HMG CoA reductase D.HMG CoA lyase

7.All the following statements about ketone bodies are true except: A.Their sythesis increases in diabetes mellitus B.They are synthesised in mitochondria C.They can deplete the alkali reserve D.They can be oxidized in the liver

8.All the following statements about carnitine are ture except: A.It can be synthesized in the human body

B.It can be synthesised from methionine and lysine

C.It is required for transport of short chain fatty acids into mitochondria D.Its deficiency can occur due to haemodialysis

9.Diets having a high ratio of polyunsaturated: saturated fatty acids can cause: A.Increase in serum triglycerides B.Decrease in serum cholesterol C.Decrease in sreun HDL D.Skin lesions

10.In glycerolphospholipids, a polyunsaturated fatty acid is commonly attached to the following carbon atom of glycerol: A.Carbon 1 B.Carbon 2

C.Both of the above D.Neither of the above 11.Lysolecithin is formed from:

A.Palmitoyl CoA and choline B.Palmitoyl CoA and ethanolamine C.Palmitoyl CoA and serine D.Acetyl CoA and choline 12.The largest apolipoprotein is:

A.ApoE B.Apo B-48 C.Apo B-100 D.Apo A-Ⅰ 13.Apolipoprotein B-100 is synthesized in:

A.Adipose tissue B.Liver C.Intestine D.Liver and intestine 14.Apoliporprotein B-48is synthesized in:

A.Adipose tissue B.Liver C.Intestine D.Liver and intestine 15.Apolipoprotein C-Ⅱ is an activator of:

A.Lecithin cholesterol acyl transferase B.Phospholipase C C.Extrahepatic lipoprotein lipase D.Hepatic lipoprotein lipase 16.Nascent chylomicron receives apolipoprotein C and E from: A.VLDL remnant B.VLDL C.LDL D.HDL 17.VLDL remnant may be converted into:

A.VLDL B.LDL C.HDL D.Chylomicrons 18.Receptors for chymicron remnants are:

A.Apo A specific B. Apo B-48 specific C. Apo C specific D. Apo E specific

19.Activated lecithin cholesterol acyl transferase is essential for the conversion of:

A.VLDL remnants into LDL B.Nascent HDL into HDL C.HDL2 to HDL3 D.HDL3 to HDL2

20.Fatty liver may be caused by:

A.Deficiency of methionine B.Puromycin C.Chronic alcoholism D.All of the above

21.Alcohol dehydrogenase converts ethanol into:

A.Acetyl CoA B.Acetaldehyde C.Acetate D.CO2 and H2O 22.Lipids are stored in the body mainly in the form of:

A.Phospholipids B.Glycolipids C.Triglycerides D.Fatty acid 23.In adipose tissue, glycerol-3-phosphate required for the synthesis of triglycerides comes mainly from: A.Hydrolysis of pre-existing triglycerides

B.Hydrolysis of phospholipids

C.Dihydroxyacetone phosphate fromed in glycolysis D.Free glycerol

24.Free glycerol cannot be used for triglyceride synthesis in: A.Liver B.Kidney C.Intestine D.Adipose tissue 25.Oxidation of fatty acids occurs:

A.In the cytosol B.In the matrix of mitochondria

C.On inner mitochondrial membrane D.On the microsomes 26.Activation of fatty acids requires all the following except: A.ATP B.Coenzyme A C.Thiokinase D.Carnitine 27.Carnitine acylcatnitine translocase is present: A.In the inner mitochondrial membrane B.In the mitochondrial matrix

C.On the outer surface of inner mitochondrial membrane

D.On the inner surface of inner mitochondrial membrane

28.De novo synthesis of fatty acids is catalysed by a multipenzyme complex which contains:

A.One-SH group B.Two-SH group C.Three-SH group D.Four-SH group

29.Acetyl CoA required for the novo synthesis of fatty acids is obtained from: A.Breakdown of existing fatty acids B.Ketone bodies C.Acetate D.Pyruvate

30.β-Oxidation of fatty acids inhibited by:

A.NADPH B.Acetyl CoA C.Malonyl CoA D.None of the above 31.The enzyme regulating extramitochondrial fatty acids synthesis is: A.Thioesterase B.Acetyl CoA carboxylase C.Acyl transferase D.Multi-enzyme complex 32.Acetyl CoA carboxylase is activated by:

A.Citrate B.Insulin C.Both of the above D.None of the above 33.Lipogenesis is decreased in all the following except:

A. Restricted caloric intake B. High fat intake C. Deficiency of insulin D. High carbohydrate intake

34.During each cycle of β-oxidation:

A.One carbon atom is removed from the carboxyl end of the fatty acid B.One carbon atom is removed from the methyl end of the fatty acid C.Two carbon atoms are removed from the carboxyl end of the fatty acid D.Two carbon atoms are removed from the methyl end of the fatty acid 35.NADPH required for fatty can come from:

A.Hexose monophosphate shunt B.Oxidative decarboxylation of malate C.Extramitochondrial oxidation of isocitrate D.All of the above

36.For extramitochondrial fatty acid sythesis, acetyl CoA may be obtained from:

A. Citrate B. Isocitrate C.Oxaloacetate D.Succinate 37.Fluidity of membranes is increased by the following consitituent:

A.Polyunsaturated fatty acids B.Saturated fatty acids C.Integral proteins D.Cholesterol

38.Acetyl CoA formed from pyruvate can be used for the synthesis of all the following except:

A.Glucose B.Fatty acids C.Cholesterol D.Steroid hormones

39.The following can be used as a source of energy in extrahepatic tissues:

A.Acetoacetate B.Acetone C.Both of the above D.Neither of the above

40.De novo synthesis and oxidation of fatty acids differ in the following respect: A.Synthesis occurs in cytosol and oxidation in mitochondria B.Synthesis si decreased and oxidation increased by insulin C.NADH is required in synthesis and FAD in oxidation

D.Malonyl CoA is formed during oxidation but not during synthesis

41.De novo synthesis of fatty acids requires all the following vitamins(or their coenzymes) except:

A.Niacin B.Pantothenic acid C.Folic acid D.Biotin 42.Acetyl CoA carboxylase:

A.Is a multienzyme protein B.Contains biotin

C.Can exist in a dimeric or a polymeric form D.All of the above 43.The initial event in carboxylation of acetyl CoA is:

A.Formation of enzyme-biotin-ATP complex B.Carboxylation of biotin C.Transfer of carboxyl group to ATP D. Transfer of carboxyl group to acetyl CoA

44.All the following statements about acetyl CoA carboxylase are correct except:

A.It is allosteric enzyme B.Its allosteric activator is citrate C.Its allosteric inhibitor is long chain acyl CoA

D.Allosteric activation involves conversion of polymeric form of the enzyme into dimeric form

45.The following are present in outer mitochondrial membrane:

A.Thiokinase (acyl CoA synthetase) and carnitine palmitoyl transferaseⅠ B. Thiokinase and carnitine palmitoyl transferase Ⅱ

C. Carnitine palmitoyl transferaseⅠand carnitine palmitoyl transferase Ⅱ D. Carnitine palmitoyl transferase Ⅱ and carnitine acylcarnitine translocase 46. The following are present in inner mitochondrial membrane: A.Thiokinase and carnitine palmitoyl transferaseⅠ B. Thiokinase and carnitine palmitoyl transferase Ⅱ

C. Carnitine palmitoyl transferaseⅠand carnitine palmitoyl transferase Ⅱ D. Carnitine palmitoyl transferase Ⅱ and carnitine acylcarnitine translocase 47.Esterification of cholesterol in plasma is catalysed by: A.Lecithin: cholesterol acyltransferase B.Acyl CoA: cholerterol acyltransterase

C.Succinyl CoA: cholesterol acyltransterase D.Malonyl CoA: cholesterol acyltransferase Answers:

1.C 2.B 3.B 4.D 5.C 6.B 7.D 8. C 9.B 10.B

11.C 12.C 13.B 14.C 15.C 16.D 17.B 18.D 19.D 20.D 21.B 22.C 23.C 24.D 25.B 26.D 27.A 28.D 29.D 30.C 31.B 32.C 33.D 34.C 35.D 36.A 37.A 38.A 39.B 40.A 41.C 42.D 43.B 44.D 45.A 46.D 47.A Questions:

1.Classify lipids, giving examples.

2.Explain the steps of beta oxidation of Palnitic acid,giving energetics. 3.What are ketone bodies? Explain the reactions lesding to the formation of them. How are they utilized in the body.

4.What are the important compounds synthesised from cholwsterol? Explain the regulation of body cholesterol pool.

5.Classify the lipoproteins. Explain their biolodical significance.

Metabolism of Amino Acids

Multiple choices questions:

1.Positive nitrogen balance is seen in:

A.Starvation B.Wasting diseases C.Growing age D.Intestinal malabsporption

2.Alanine can be synthesised from:

A.Glutamate B.Pyrubate and glutamate C.Pyruvate and α-ketoglutarate D.Aspartate andα-ketoglutarate

3.All the following statements about aspartate are true except:

A.It is a non-essential amino acid B.It is a dicarboxylic amino acid

C.It can be sythesised from pyruvate and glutamate D.It can be converted into asparagine

4.All the following statement about proline are true except: A.It is an imino acid B.It can be synthesised from glutamate

C.It can be catabolised to glutamate D.Free proline can be hydroxylated to hydroxyproline

5.A protein rich in hydroxyproline is:

A.Prolamin B.Procollagen C.Collagen D.Proinsulin

6.Hydroxylation of phenylalanine requires all of the following except: A.Phenlyalanine hydroxlase B.Tetrahydrobiopterin C.NADH D.Molecular oxygen

7.During catabolism of amino acids, their groups are transferred mainly to: A.Pyruvate B.Oxaloacetate C. α-ketoglutarate D.Ornithine 8.The amino acid that undergoes oxidative deamination at a significant rate is: A.Alanine B.Aspartate C.Glutamate D.Glutamine 9.Free ammonia is released during:

A.Oxidative deamination of glutamate B.Catabolism of purines C.Catabolism of pyrimidines D.All of the above

10.An organ which is extremely sensitive to ammonia toxicity is: A.Liver B.Brain C.Kindey D.Heart

11.Ammonia is transported from muscles to liver mainly in the form of: A.Free ammonia B.Glutamine C.Asparagine D.Alanine

12.Immediate detoxification of ammonia is done in brain by fixing it in the form of:

A.Glutamine B.Alanine C.Aspartate D.Asparagine 13.All the following statements about glutamine are true except: A.Glutamien is formed solely to detoxify ammonia

B.Synthesis of glutamine from glutamate and ammonia requires energy C.Renal tubular cells are a major site for breakdown of glutamine D.Glutamine can be incorporated in proteins 14.The major site of urea synthesis is:

A.Brain B. Kidneys C. Liver D. Muscles

15.Congenital absence of ornithine transcarbamoylase cause: A. Hyperammonaemia typeⅠ B. Hyperammonaemia type Ⅱ C. Hyperornithinaemia D.Citrullinaemia

16.All of the following are glycogenic amino acids except: A. Glycine B. Alanine C. Leucine D. Valine 17.A ketogenic amino acid among the following is: A. Leucine B. Serine C. Threonine D. Proline

18.A donor of labile methyl group is:

A.Methionine B. S-Adenosylmethionine C. Methylmalonyl CoA D.All of the above

19.Homogentisic acid is formed from:

A. Homoserine B. Homocysteine C.Tyrosine D. Tryptophan 20.All the following statements about albinism are correct except:

A.Tytosine hydroxylase(tyrosinase) is absent or deficient in melanocytes B.Skin is hypopigmented C.It results in mental retardation D.Eyes are hypopigmented

21.All the following feature are present in alkaptonuria except:

A.Absent of homogentisate oxidase B.Urine darkens on exposure to air

C.Pigmentation of connective tissue D.Increased conversion of tyrosine into melanin

22.All the following are required for the formation of creatin except:

A.Creatine kinase B.Arginine C.S-Adenosylmethionine D.Glycine 23.Histamine is formed histidine by:

A.Deamination B.Dehydrogenation C.Decarboxylation D.Carobxylation

24.DOPA is an intermediate in the synthesis of:

A.Thyroid hormones B.Catecholamines C.Melanin D.Catecholamines and melanin

25.All the following can be formed from tryptonphan except: A.Niacin B.Serotonin C.Melatonin D.Melanin 26.All the following statements about trysin are true except: A. Its precursor is secreted by exocrine portion of pancreas

B. It is formed by the action of enterokinase on trypsinogen

C.Active trypsin can also act on tis own precursor to form more trypsin D.It acts preferentially on peptide bonds involving aromatic amino acids 27.A low-phenylalanine diet is recommended in:

A.Phenylketonuria B.Alkaptonuria C.Maple syrup urine disease D.Hartnup’s disease

28.All the following statements about transamination are correct except:

A.The reaction is reverible B.It requires pyridoxal phosphate as a coenzyme C.All amino acids can undergo transamination

D.A Schiff base is formed as an intermediate during the reaction 29. All the following statements about ornithine are correct except: A.It is formed during creatine synthesis

B.It is formed during synthesis of nitric oxide from arginine

C.It is formed as an intermediate in urea cycle D.It can form polyamines 30.Cysteine is required to synthesise:

A.Taurine B.CoA C.Glutathione D.All of the above

31.The only fate of amino acids liberated from hydrolysis of body proteins is: A.Synthesis of glucose and /or fatty acids

B.Reutilisation for synthesis of protein C.catabolism D.None of the above

32.One-carbon unit is liberated during catabolism of: A.Histidine B.Serine C.Glycine D.All of the above Answers:

1.C 2.B 3.C 4.D 5.C 6.C 7.C 8.C 9.D 10.B

11.D 12.A 13.A 14.C 15.B 16.C 17.A 18.B 19.C 20.C 21.D 22.A 23.C 24.D 25.D 26.D 27.A 28.C 29.B 30.D 31.D 32.D Questions:

1.How will you classify amino acids based on their nutritional importance? 2.Give an account of the transamination reactions. Give two suitable examples.

3.Describe the steps of catabolism of phenylalanine and tyrosine. Indicate the inborn errors of metabolism associated with this pathway.

Metabolism of Nucleotides

Multiple choices questions:

1.Nucleotides required for the synthesis of nucleic acids can be obtained from: A.Dietary nucleic acids and nucleotides B.De novo synthesis

C.Salvage of pre-existing bases and nucleosides D.De novo synthesis salvage

2.In mammals, the major site foe de novo synthesis of purine nucleotides is: A.Bone marrow B.Liver C.Brain D.Muscles

3.The nitrogen atoms for de novo synthesis of purine nucleotides are provided by:

A.Aspartate and glutamate B.Aspartate and glycine

C.Aspartate, glutamine and glycine D. Aspartate, glutamate and glycine 4.For de novo synthesis of purine nucleotides, aspartate provides: A.Nitrogen 1 B.Nitrogen 3 C.Nitrogen 7 D.Nitrogen 9

5.In the pathway of de novo synthesis of purine nucleotides, all the following are allosteric enzymes except:

A.PRPP glutamyl amido tranferase B.Adenylosuccinate C.IMP

dehydrogenase

D.Adenylosuccinase

6.An aloosteric inhibitor of PRPP gluramyl amido transferase is: A.AMP B.ADP C.GMP D.All of the above

7.An allosteric inhibitor of adenylosuccinate synthtase is: A.AMP B.ADP C.GMP D.GDP

8.The first reaction unique to purine nucleotide synthesis is catalysed by: A.PRPP synthetase B.PRPP glutamyl amido transferase

C.Phosphoribosyl glycinamide synthetase D.Formhl transterase 9.Free purine bases which can be salvaged are:

A.Adenine and guanine B.Adenine and hypoxanthine C.Guanine and hypoxanthine

D.Adenine, guanine and hypoxanthine

10.The enzyme required for salbage of free purine bases is: A. Adenine phosphoribosyl transferase

B. Hypoxanthine guanine phosphoribosyl transferase

C. Both of the above D. Neither of the above 11.Deoxycytidine kinase can salvage:

A.Deoxycytidine B.Deoxyadenosine C.Deoxyguanosine D.All of the above

12.Adenosine kinase can salvage:

A.Adenosine B.Adenosine and deoxyadenosine C.Adenosine and guanosine

D.Adenine and adenosine

13.Salvage of purine bases is regulated by:

A.Adenosine phosphoribosyl transferase B.Hypoxanthine guanine phosphoribosyl transferase

C.Availability of PRPP D.None of the above 14.PRPP is used for all the following except:

A.De novo synthesis of purine nucleotides B.De novo synthesis of pyrimidine nucleotides

C.Salvage of purine based C.Salvage pyrimidine bases

15.The enzyme common to catabolism of all the purines is:

A.Adenosine deaminase B.Purine nucleoside phosphorylase C.Guanase D.None of the above

16.For synthesis of CTP from UTP, the amino group comes from: A.Amide group of asparagine B.Amide group of glutamine

C.α-Amino group of glutamine D.α-Amino group of glutamate

17.For the synthesis of TMP from dUMP, a coenzyme is required which is: A.N 10 -Formyl tetrathdrofolate B.N 5 -Methyl tetrahydrofolat

C.N 5 ,N 10 -Methylene tetrahydrofolate D.N 5 -Formimino tetrahydrofolate 18.Tetrahydrofolate is required as a coenzyme for the synthesis of: A.NMP B.CMP C.TMP D.All of the above

19.All the following statements about thioredoxin reductase are true except:

A.It requirese NADH as a coenzyme B.Its substrates are ADP, GDP, CDP and UDP

C.It is activated by ATP D.It is inhibited by Dadp

20.De novo synthesis of pyramiding nucleotides is regulated by:

A.Carbamoyl phosphate synthetase B.Aspartate transcarbamoylase C.Both of the above D.Neither of the above 21.Aspartate tranacarbamoylase is inhibited by: A.CTP B.PRPP C.ATP D.TMP 22.β-Alanine is formed from catabolism of:

A.Thymine B.Thymine and cytosine C.Thymine and uracil D.Cytosine and uracil

23.The following coenzyme is required for catabolism of pyrimidine bases: A.NADH B.NADPH C.FADH2 D.None of the above

24.All of the following statements about uric acid are ture except:

A.It can be formed from allantoin

B.Formation of uric acid stone in kidneys can bu decreased by alkalinisation of urine

C.Uric acid begins to dissociate at PH about 5.8

D.It is present in plasma mainly as monosodium urate

25. All of the following statements about primary gout are ture except: A.Uric acid stones may be formed in kidneys

B.Arthritis of small joints occurs commonly C.Urinary excretion of uric acid is decreased D.It occurs predominantly in males

26.All the following statements about allopurinol are ture except: A.It is a structural analogue of uric acid

B.It can prevent uric acid stone in the kidneys

C.It increases the urinary excretion of xanthine and hypoxanthine D.It is a competitive inhibitor of xanthine oxidase

27.Increased urinary excretion of orotic acid can occur in deficiency of: A.Orotate phosphoribosyl transferase B.OMP decarboxylase

C.Mitochondrial ornithine transcarbamoylsase D.Any of the above 28.Deoxyribonucleotides are formed by the reduction of:

A.Ribonucleosis B. Ribonucleoside monophosphates C.Ribonucleoside diphosphates

D.Ribonucleoside triphosphates

29.5-Phosphoribosyl-1-pyrophosphate is required for all of the following except:

A.De novo synthesis of purine nucleotides B. De novo synthesis of pyrimidine nucleotides

C.Salvage of adenine D.Salvage of cytosine

30.An anti-cancer drug that acts b inhibiting nucleotide synthesis is: A.Allopurinol B.Methotrexate C.α-Amanitin D.Azathioprine 31.dUMP is converted into TMP by:

A.Methylation B.Carboxylation C.Deamination D.Decarboxylation 32.Uric acid is:

A.Formed from xanthine by a metalloflavoprotein enzyme B.An allosteric inhibitor of xanthien oxidase

C.Excreted in bile D.A metabolite of purines and pyrimidines 33.Glutamine is required for de novo synthesis of:

A.Purine nucleotides B.Pyrimidine nucleotides C.Both of the above D.Neither of the above

34.All the following statements about adenine and guanine nucleotides are correct except:

A.Their de novo synthesis occurs from a common intermediate B.They are salvaged from free bases by a common enzyme

C.They are catabolised to a common end product D.They occur in DNA as well as RNA

Answers:

1. D 2.B 3.C 4.A 5.D 6.C 7.A 8.B 9.D 10.C

11.D 12.B 13.C 14.D 15.B 16.B 17.C 18.C 19.A 20. C 21.A 22.D 23.B 24.A 25.C 26.A 27.D 28.C 29.D 30. B 31.A 32.A 33.C 34.B Questions:

1.Give the sources of carbon and nitrogen atom of purine and pyrimidine rings. 2.How are the purine nucleotides degraded? Add a note on abnormalities due to excessive purine catabolism.

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