Biochem-mcq-GATE

8/7/2019 Biochem-mcq-GATE

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Biochemistry question bank v 1.0eMultiplechoicequestions.Contains 225unsolvedquestionsforbiochemistry,forchaptersaminoacids,proteins,metabolism.DifficultyLevelismoderate.

2009

EduGATErKnoxville8/1/2009

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[email protected],

c=IN

Date: . . : : + ' '


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1. On the scale of the CPK models, i.e. magnificationof 108, anaverage amino acid would be about the size of a

A. a house

D. an appleB. a truckE. a marbleC. a large pillow

2. DNA base pairs are connected by hydrogen bonds.What force causes them to "stack" against eachother in the double helix?

A. more hydrogen bondsD. ionic forcesB. van der Waals forcesE. none of the aboveC. hydrophobic attraction

3. Which amino acid has an R group which can NOT

form hydrogen bonds?A. SD. YB. LE. EC. T

4. The planar structure of a peptide bond includes

how many atoms?A. 2D. 10B. 4E. 24C. 6

5. Secondary structures are generally stabilized byA. salt bridgesD. hydrophobic forcesB. magnetism

E. peptide H bondsC. van der Waals forces

8. Some proteins can fold up rapidly and

spontaneously. Proteins which needchaperones (heat shock proteins, Gro-EL) are likelyto be

A. alpha helicalD. beta sheetsB. large, hydrophobicE. from yeast or fungus

C. small, globular

9. Specific cleavage at F, Y, and W residues iscatalyzed by

A. chymotrypsinD. acetylcholinesteraseB. trypsin

E. none of the aboveC. cyanogen bromide

10. Home pregnancy tests detect low levels of hCGby means of

A. Western BlottingD. Edman Degradation

B. Equilibrium sedimentationE. ELISAC. Amino Acid Analysis

11. Now that several genomes have been sequenced,plans are in the works to collect massive amountsof data about 3-D protein structures. Whattechnique yields thisinformation?

A. ion-exchange


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D. rate sedimentationB. affinity chromatographyE. Edman degradationC. X-ray crystallography

12. SDS PAGE separates proteins by

A. native charge onlyC. size onlyB. size and native chargeD. none of the above

13. If one strand of a short stretch of DNA reads

AGGTTC, the other strand will read

A. AGGTTCD. AGCTGCB. TCCAAGE. CTTGGAC. GAACCT

14. Bacterial transformation was first discoveredin the 1920's by

A. Fred GriffithD. Oswald AveryB. Fred SangerE. Hershey and BarrC. Fred Flintstone

15. The size of the genome of E. coli is roughly

A. 4,600 base pairsD. 4,600,000 base pairsB. 46,000 base pairsE. 46,000,000 base pairsC. 460,000 base pairs

16. When you heat a solution of double-strandedDNA you can tell when the strands

separate into single stranded DNA because

A. solution turns blueD. vial gets coldB. UV absorption increases

E. DNA precipitates outC. UV absorption decreases

17. The F6 His is tightly bound to the heme iron, andis called the:

A. distal HisD. vestigial His

B. proximal HisE. retro-HisC. medial His

18. If a solution of Hemoglobin is oxygenated to1/2 of its capacity, what would you expect to find inthe solution?

A. The solution would contain only Hb(O2)2B. The solution would contain roughly equal partsof Hb, Hb(O2)2, and Hb(O2)4C. The solution would have mostly Hb(O2)2 withsome Hb and Hb(O2)4D. The solution would be 1/2 Hb(O2)4 and 1/2 Hb.E. None of the above

19. What is the heme group?A. a lipidD. a tetrapyrroleB. a proteinE. a steroidC. a carbohydrate

20. 2,3 BPG binds to Hemoglobin in its "Tense" deoxyform but not to the "Relaxed"form. Why can't it bind to "Relaxed" Hb?


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A. the oxygen gets in the wayD. it does bindB. the heme iron is too bulkyE. no negative chargesC. central cavity of tetramer too small

21. Consider the simple chemical reaction, A -> B.Suppose that at the start of the reaction, A is 11 Mand B is 1 M. At the end of the reaction, A is 6 M andB is 6 M. To calculate the Gibbs Free Energy at thestart of the reaction, we would have to solve:

A. G = 1 + RTln(1)

D. G = 0 + RTln(1/11)B. G = 0 + RTln(11)E. none of the aboveC. G = 11 + RTln(12)

22. Is it possible for a reaction with a positive GibbsFree Energy change to go forward? Note, this is notthe Standard Free Energy change.

A. yes, they always go forwardC. sometimes forwardB. no, they can never go forwardD. none of above

23. One difference between Competitive and Non-competitive Inhibitors is that Competitive Inhibitors

A. bind at a distance from the active siteB. trap S in the active siteC. prevent S from binding at the active siteD. always change the VmaxE. none of the above

24. If a given substrate has a high Km with an enzymewe usually assume

A. weak binding

C. reaction is very fastB. strong binding

D. "substrate" is an inhibitor

25. The difference between a Cerebroside and a

Ganglioside is that

A. one is a sphingolipid, the other a phosphatidyllipidB. one contains a fatty acid amide, the other a fattyesterC. one contains a sugar head group, the other anoligosaccharide

D. one has sugar phosphate, the other simply a sugar

26. Eucaryotic cell membranes are strengthened by

A. the cell wallD. polyunsaturated fatsB. glycolipidsE. all of the above

C. proteins like Spectrin

27. Cardiolipin is found in

A. the mitochondrial inner membraneb. the lysosomec. the nuclear membraned. the endoplasmic reticulum

e. the eucaryotic cell membrane

28. Primary Active Transport fueled by (what) totransport (what)?

A. sugars, sugarsD. GDP, proteinsB. ATP, ionsC. cAMP, amino acidsE. none of the above


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29. The Acetylcholine Receptor is composed of howmany subunits?A. 1D. 6B. 4

E. 8C. 5

30. Potassium can not pass through the voltagegated Sodium Channel because

A. inactivation prevents itD. K+ is too large

B. too much Sodium gets in wayE. none of the aboveC. K+ is too positive

31. Protein Kinase C transfers a phosphate toSerine in substrate proteins containing thesequence RKGSLRQ. Like Protein Kinase A, PKC has aregulatory domain with a pseudosubstrate

sequence. Which of the following would be a goodcandidate for this sequence?

A. RAGSLRQD. RKGSARQB RKASLRQE. RKGSLAQC. RKGALRQ

32. An inhibitor of the enzyme Acetylcholinesterasecould be used as

A. a sleeping pillD. antibioticB. inhibitor of gastric acidityE. nerve gasC. anti-inflammatory

33. The standard free energy change for transportof Glucose across a membrane would be

A. positiveB. negative

C. zero

34. In a handout, research was described thatprovided the "Fountain of Youth" for fruit flies, by:

A. cosmetic surgeryD. transfecting SOD and CatalaseB. getting plenty of sleep

E. sit-ups and aerobaticsC. antioxidant vitamins

35. We share our antibody-diversity generatingsystem with

A. all plants and animalsD. all jawed vertebrates

B. all higher animalsE. mammals onlyC. all deuterostomes including starfish etc.

36. The human genome holds some 30,000 genes.Roughly what percentage of these genes aredevoted to producing antibody diversity?

A. 0.001%D. 1.0 %B. 0.01%E. 10 %C. 0.1%F. 100%

37. The antigen binding site of IgG is composed of

A. VH and VLD. 2 VL


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B. VH and CHE. none of the aboveC. 2 VH

38. The heavy chain of IgG is made up of beta

sandwich segments which are clearly visible in thestructure. How many beta sandwiches are there inone heavy chain?

A. 12D. 3B. 6E. 2

C. 4F. 1

39. If concentrations in a cell are [ATP] = 2 mM,[ADP] = 0.2 mM, and [AMP] = 0.02 mM what is theenergy charge?A. 2.22D. 0.946

B. 1.0E. 0.803C. 0.992

40. What would be a good example of a "Stage III"process, in Krebs' analysis of catabolism?

A. Amylose hydrolysisD. protein hydrolysisB. GlycolysisE. none of the aboveC. Citric Acid Cycle

41. You drink a glass of milk. An hour later you haveintestinal cramps and other gut symptoms. Chancesare you have

A. galactosemiaC. lactose intolerance

B. diabetesD. malaria

42. Glucose which has been oxidized to have acarboxyl group at C-6 is called:

A. GluconateD. FructoseB. GlucuronateE. SedoheptuloseC. Glucarate

43. D-Xylulose forms a glycoside when a substituent

is added to which position?

A. 1D. 4B. 2E. 5C. 3

44. Interpret the "chair" structure shown below.What is the name of the sugar represented?

A. alpha-D-MannoseD. beta-D-AlloseB. alpha-D-GlucoseE. beta-D-RiboseC. alpha-D-Galactose

45. When insulin signals ingestion of food, GLUT-4receptors are

A. rapidly synthesizedD. translocated to outer membraneB. rapidly destroyedE. blocked by binding insulinC. put into inactive mode


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46. Aldolase forms a covalent connection betweensubstrate and a residue of

A. lysineD. glutamate

B. serineE. alanineC. cysteine

47. The normal mechanism of G3PDH is directlydisrupted byA. cyanideD. citrate

B. 2, 4 DNPE. arsenateC. Fru-2,6 BP

48. The graph below represents the kinetics of PFK-Iwhen F6P is held constant and ATP is varied. Thelines marked "+" show the kinetics in the presenceof what?

A. cyclic AMPD. Glucose 6 PB. Calcium ionE. Fru-2,6-BPC. 2,3 BPG

49. Which compound allosterically decreases the

activity of Isocitrate DH?

A. ATPD. F2,6 BPB. ADPE. CitrateC. cAMP

50. Succinate DH occurs where?

A. mito matrix

D. outer membraneB. mito inner membraneE. lumen of endoplasmic reticulumC. cytoplasm

51. How many "~P" or "ATP" are produced by theoxidation of one mole of Pyruvate in respiringmitochondria?

A. 2D. 12.5B. 6E. 30

C. 10

52. In the mechanism for the Pyruvate DH Complex,what re-oxidizes Dihydrolipoamide to Lipoamide?

A. NADPHD. FAD and NAD+B. NAD+ only

E. none of the aboveC. FAD only

53. Acetyl CoA labeled at C-1 is introduced into theCitric Acid Cycle. Where does the carbon show up inalpha-Ketoglutarate during the first turn of thecycle?

A. C-1D. C-4B. C-2E. C-5C. C-3

54. The Fe4S4 Iron Sulfur Cluster is shaped like a

A. sphereD. baseball diamondB. doughnut


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E. cubeC. triangle

55. Compared with cytochromes, iron sulfurclusters are

A. higher in energy, evolutionarily olderB. higher in energy, evolutionarily youngerC. lower in energy, evolutionarily olderD. lower in energy, evolutionarily youngerE. none of the above

56. A "Racker's Knob" consists of the F1 "knob" and

the transmembrane For. Themovement of protonsinward through the Racker's Knobs causes rotationof

A. F1 onlyD. neitherB. Fo onlyE. alpha and beta subunits of F1

C. F1 and Fo

57. The existence of the ATP-ADP shuttle wasproven when a specific inhibitor was discovered the inhibitor is

A. BungarotoxinD. CyanideB. AtractylosideE. Antimycin AC. Amytal

58. During the Q-cycle in mitochondria, "inwardfacing" Q is reduced to QH2 by interacting directlywith what?

A. cytochrome c

D. bHB. Rieske FeS

E. bLC. cytochrome c1F. none of the above

59. The genetic disease Wernicke-Korsakoff

Syndrome was described in a handout and in class. Itcan cause brain damage, and results from weakbinding between

A. Transketolase and TPPD. Glycogen and Phosphorylase aB. Transaldolase and TPPE. none of the above

C. G6PDH and NADP+

60. If we run five molecules of hexose (Fru-6-P orGlu-6-P) through the oxidative branch of thePentose Phosphate Pathway, we will get

A. 5 Rib-5-P and 5 NADPHD. 6 Rib-5-P and 5 NADH

B. 5 Rib-5-P and 10 NADPHE. 6 Rib-5-P, 5 NADPH, 5 NADHC. 6 Rib-5-P

61. The mechanism of Transketolase depends on acovalent connection between substrate and

A. lysineD. trans-fatty acidsB. cysteineE. TPPC. glucose

62. A deficiency of G6PDH can lead to

A. Pamaquine induced hemolytic anemiaD. a Selenium deficiency

B. Wernicke-Korsakoff SyndromeE. all of the above


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C. Diabetes

63. Why is G6Pase a "dangerous" enzyme?

A. it forms peroxides

D. makes holes in membranesB. uses up NADPHE. it's radioactiveC. wastes energy, lets glucose leave the cell

64. Glycogen Synthase lengthens the chain ofglycogen by reacting with

A. Glucose-1-PD. UDP-GlucoseB. Glucose-2-PE. UDP-GalactoseC. Glucose-6-P

65. You can exhaust your supply of muscle glycogenby

A. smoking a cigarD. taking a final examB. walking to classE. running a marathonC. weight training one hour

66. A glycogen molecule has hundreds orthousands of non reducing ends, and

A. hundreds of non-reducing endsB. one non-reducing end, free to reactC. one non-reducing end, attached to UDPD. one non-reducing end, attached to Glycogenin

67. A patient with cirrhosis of the liver who statesthat he never drinks alcohol is biopsied. When the

glycogen biopsy is analyzed in the lab, breakdownwith the normal enzymes yields 95% Glucose-1-P and

only 5% Glucose. Which Glycogen Storage Diseasedoes the patient have?

A. I lack of G6PaseD. V phosphorylase defic.

B. III lack of Debranching Enz.E. none of the aboveC. IV lack of Branching Enz.

68. During glycogen synthesis, the "Branching"enzyme moves how many glucose residues from themain chain to form a branch?

A. 1D. 11B. 3E. 25C. 7

69. The complete oxidation of a molecule ofPalmitate (16:0) in respiring mitochondria would

cause a net gain of how many ATP?

A. 131D. 106B. 129E. 38C. 108

70. The Reductase used during catabolism of -evenfatty acids adds hydrogens at positions:

A. 1 and 2D. 4 and 5B. 2 and 3E. 2 and 5C. 3 and 4

71. The fatty acid 20:3 cis 11, 14, 17, was derivedfrom a common dietary fatty acid. By comparing


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numbers we can deduce that the metabolic sourcefor this fatty acid is probably:

A. palmiticD. linolenic

B. oleicE. none of the aboveC. linoleic

72. During fatty acid synthesis, a _____ double bondis reduced by the cofactor _____

A. cis, FADH2

D. trans, NADPHB. trans, FADH2E. cis, NADHC. cis, NADPH F. trans, NADH

73. If the R group of an amino acid is -CH3 , then the

name of this compound is

a. Methyl amino acid

b. 2-aminopropanoic acid

c. Alanine

d. All of the above

e. b and c

74. Amino acids are zwitterions when they are

a. In any solution

b. At physiological pH, pH = 7.4

c. In acidic solutions only

d. In alkaline solutions only

e. All of the above

75. An amino acid with two chiral carbon atoms

a. Is unstable

b. Can exist in 4 forms all of which are

superimposable

c. Can form three possible stereoisomers

d. Can form four possible stereoisomers

e. Can form five possible stereoisomers

76. The R group of an amino acid determines if it is

a. Hyrophilic or hydrophobic

b. Polar or nonpolarc. Charged or uncharged

d. An acid or a base

e. All of the above

77. Proline is distinct among the 20 commonly

found amino acids because

a. It is a ring compound

b. It is hydrophilic and ionic

c. The nitrogen of the amino group is in a ring

d. The carbon of the carboxyl group is in a ringe. It has little effect on protein structure


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78. Tyrosine and tryptophan are less hydrophobic

than phenylalanine because

a. Phenylalanine has an indole group

b. Phenylalanine has no polar group in the side chain

c. Phenylalanine is a phenol

d. Tyrosine and tryptophan have smaller R groups

e. All of the above

79. The amino acids in polypeptide chains which

contain sulfur (S) are

a. Cysteine, cystine, and methionine

b. Cystinec. Methionine only

d. Cysteine only

e. Cysteine and methionine

80. Although the hydroxyl groups in serine and

threonine are uncharges, they can react within

active sites of some enzymes because

a. The hydroxyl group is uncharged

b. The hydroxyl group can be polar

c. The hydroxyl group can fit into the sited. All of the above

81. Basic amino acids are ______ (positive, negative) at

pH 7 and acidic R group amino

acids are ______ (positive, negative) at pH 7.

a. Negative; positive

b. Negative; negative

c. Positive; negative

d. Positive; positive

82. Arginine is the most basic of the 20 amino acids

because its side chain is _________ under most cell

conditions.

a. Very highly chargedb. Hydrophobic

c. Titrated

d. Protonated

e. Negatively charged

83. At the isoelectric pH of an amino acid which has

two pKa values the net charge is

a. 0.5

b. 1

c. 0d. -1


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84. The pH inside cells is normally near pH 7. At pH 7

which statement is true about the charges

(ionization state) of the -Carboxyl and -Amino

groups of an amino acid?

a. The -Carboxyl group is 1- and the -Amino group is

1+.

b. The -Carboxyl group is 1+ and the -Amino group

is 1-.

c. The -Carboxyl group is 1- and the -Amino group is

uncharged.

d. Both groups are uncharged (not ionized) at pH 7.

85. Which structure below is appropriate for

glycine at neutral pH?

a. H2 NCH2 COOH

b. H2 NCH2 COO+

c. H3 NCH2 COO+

d. H3 NCH2 COOH

86. What is the net charge on the tripeptide Gly-Arg-

Lys at pH 7? The table below gives the pKa 's of the

ionizable groups on the free amino acids.

a. -1b. 0

c. +1

d. +2

87. The ionic charges associated with a protein

molecule are ____________________.

a. mostly contributed by the side chains of

constituent amino acids

b. determined by the contribution from the -

carboxyl group, -amino group and sidechain of every amino acid in the protein

c. contributed by only the N-terminal and C-terminal

residues

d. independent of the amino acid composition and

depend only on pH

88. A mixture of four proteins (A, B, C and D) is

applied to a gel-filtration column. Given the

information supplied, which will elute first?


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a. C

b. B and D elute together

c. A

d. cannot answer without information about the

isoelectric point

89. An octapeptide was determined to have the

following amino acid composition:

Lys (2), Phe (2), Gly (1), His (1), Leu (1), Met (1).

The native peptide was run through one cycle of the

Edman degradation and the PTH-leucine derivative

was identified by HPLC. When the native peptide was

exposed to cyanogen bromide (CNBr), a heptapeptide

and free glycine were recovered. Incubation of the

native protein with trypsin gave a tetrapeptide, a

tripeptide, and free lysine. The peptides were

separated and each run through one cycle of the

Edman degradation. The tetrapeptide

yielded the PTH-leucine derivative, and the tripeptide

yielded the PTH-phenylalanine derivative. Incubation

of the native protein with pepsin produced a

dipeptide and two tripeptides. The amino acid

composition of the tripeptides (not the order) were

determined to be (Phe, Gly, Met) and (Phe, Lys, Lys).

What is the sequence of the octapeptide?Specificities of Proteases

CNBr Met (C)

Trypsin Lys, Arg (C)

Pepsin Phe, Trp, Tyr (N)

a. Leu-His-Phe-Lys-Lys-Phe-Met-Gly

b. Gly-Met-Phe-Lys-Lys-Phe-His-Leu

c. Met-Leu-Phe-Lys-Phe-Gly-Lys-His

d. Leu-His-Lys-Lys-Phe-Phe-Gly-Met

e. His-Phe-Leu-Lys-Lys-Phe-Met-Gly

90. Which of the following statements is FALSE?

a. Enzymes make reactions 103 to 101 7 times faster.

b. Enzymes lower the amount of energy needed for a

reaction.

c. Enzymes are unchanged during a reaction.

d. Enzymes speed up the attainment of a reaction

equilibrium.

e. Enzymes are proteins.

91. An enzyme that catalyzes conversions of L-

sugars to D-sugars is called an

a. Lyase

b. Hydrolase

c. Synthetase

d. Synthasee. Isomerase


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92. In a first order chemical reaction, the velocity

of the reaction is proportionate to the _____, while

in a zero order reaction, the velocity of the

reaction is proportionate to _____.

a. Amount of enzyme; concentration of substrate

b. Concentration of substrate; amount of enzyme

c. Concentration of substrate; the speed of the

reaction

d. The speed of the reaction; concentration of

substrate

93. The Michaelis constant, Km , is

a. The maximum velocity that any given enzyme

reaction can achieve

b. The substrate concentration which gives the best

enzyme assay for an enzyme

reaction

c. The substrate concentration when the reaction is

half the way toward the maximal

velocity

d. The maximal velocity divided in half

94. In the Lineweaver-Burk plot of an enzymereaction, the Km is determined by

a. The x intercept

b. The y intercept

c. The reciprocal of the x intercept

d. The reciprocal of the y intercept

e. Both a and c

95. Increasing the concentration of a classic

competitive inhibitor has no effect on the maximum

velocity of an enzyme-substrate reaction.

7. A nucleophile is an electron poor species.

96. In the reaction below Y- is _________________.

Y- + CH2X CH2 Y + Xa.

the leaving group

b. the attacking electrophile

c. the reaction intermediate

d. a nucleophile

97. The substrate specificity of serine proteases is

primarily due to

a. A specificity pocket in the protein.

b. The positions of specific side chains of serine,

histidine, and aspartate


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c. Distinct backbone conformations of the

individual proteins

d. a and b

e. a, b and c

98. Acyl-group-transfer reactions often involve

which coenzyme?

a. Coenzyme A

b. NAD+

c. cytochrome c

d. all of the above

99. The simplest aldose is the chiral molecule

glyceraldehyde.

12. All D-enantiomers of carbohydrates are

dextrorotatory.

100. The structure of D-arabinose is shown below.

How many stereoisomers are possible for

this molecule (including the one shown)?

a. one

b. four

c. sixd. eight

101. Below is the structure for a cyclic D-

monosaccharide. Which is the anomeric carbon

atom?

a. 1

b. 2

c. 3

d. 4

e. 5

15. In solution -D-glucose and -D-glucose

_____________.

a. rapidly polymerize to form a heteropolymer


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b. can never exist together

c. form a racemic mixture

d. form an equilibrium mixture

102. Hemoglobin is a tetramer which can be thought

of as two dimers. The change from deoxyhemoglobin

to (tetra) oxyhemoglobin causes the relative

positions of the 2 dimers to rotate about how many

degrees?

A. 4 D. 90

B. 9 E. 120

C. 15

103. The allosteric modulator 2,3 BPG is unstable.

If blood is stored badly, what can go wrong?

A. Hemoglobin precipitates out causing sickling of

RBC

B. Hemoglobin "soaks up" oxygen, binds too avidly

C. Hemoglobin separates into monomers

D. BPG decomposes to carbon monoxide, patient

suffocates

104. What is the trigger for conformational change

when oxygen binds to hemoglobin?

A. Iron moves into plane of ring, brings along

proximal Histidine

B. Iron moves out of plane of ring, pushing on distal

Histidine

C. EF helix closes up trapping oxygen inside heme

pocket

D. There is more space for 2,3 BPG, so more binds

105. When certain muscles are exercising, and

metabolizing lots of glucose, what local effect

does this have on hemoglobin?

A. blood moves faster through this tissue, less

oxygen released

B. carbon dioxide produces high local pH, less

oxygen released

C. lactic acid lowers local pH, more oxygen is

released

D. there is no particular effect

106. Fructose-6-phosphate forms a five membered

ring in solution. The ring is connected by what sort

of structure?

A. acetal

D. hemiketalB. ketal


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E. xylan

C. hemiacetal

107. D-Galactose and D-Glucose are

A. 2 epimers

D. 5 epimers

B. 3 epimers

E. anomers

C. 4 epimers

F. isomers

108. The disaccharide drawn at right is

A. Sucrose

D. Cellobiose

B. Maltose

E. Stachyose

C. Lactose

109. Sephadex is a brand named Dextran, used in gel

filtration columns. Chemically, Sephadex is poly

(what?) linked (how?).

A. Galactose, a 1,4

D. Glucose a 1,6B. Glucose, a 1,4

E. Galactose b 1,4

C. Mannose a 1,6

110. A cerebroside is made up of Sphingosine plus

what?

A. 2 fatty acids, glucose, phosphate

D. fatty acid, glucose

B. fatty acid, glucose, phosphate

E. fatty acid, choline, phosphate

C. ceramide, glucose

111. Which lipid is represented here?

A. Lecithin

C. Phosphatidyl Serine

B. Cardiolipin

D. Phosphatidyl Ethanolamine

112. A common fatty acid is Linoleic Acid, which has

the structure

A. 18:0

D. 18:2, 6, 9

B. 18:1 7

E. 18:2, 9, 12

C. 18:3 9, 12, 15

F. 16:1, 8


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113. One enzyme found in cobra venom is

Phospholipase A2, which cleaves membrane

phosphatidyl lipids producing

A. Diacylglycerol

D. Triglycerides

B. Phosphatidate

E. Saponification

C. Lysolecithin

114. What is Anabolism?

A. DNA repair

D. All "energy reactions" in cell

B. building molecules

E. none of the above

C. breaking down foods

115. Glycolysis is part of which of "stage" of

catabolism?

A. I

C. III

B. II

D. not part of catabolism

116. Several cofactors including Coenzyme A, FAD,

and NAD have what in common?

A. Nicotinamide

D. ADP moiety

B. Pantothenate

E. A selenium atom

C. Flavine

117. Which cofactor forms a Schiff Base with

substrate?

A. Biotin

D. Thiamine

B. Lipoic Acid

E. Coenzyme A

C. Pyridoxal Phosphate

118. The mechanism of G3PDH involves covalent

attachment of substrate to which amino acid at the

enzyme's active site?

A. Ser

D. His

B. Cys

E. GluC. Lys


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119. What is the significance of Fru-2,6-

bisphosphate in the cell?

A. "I'm hungry"

D. "Too much Calcium"

B. "not enough Glucose"

E. "Too much AMP"

C. "there's a lot of Glucose"

120. The greatest difference between Aerobic and

Anaerobic fates of Pyruvate comes in the way

(what?) is utilized.

A. ATP

D. NADH

B. Coenzyme A

E. Glyceraldehyde

C. Thiamine

121. Which Glycolysis enzyme has an unusually high

positive standard free energy change (in the

"forward" direction of Glycolysis)?

A. Aldolase

D. UDP Gal EpimeraseB. Hexokinase

E. PG Kinase

C. Fructonase

122. The Citric Acid Cycle occurs where in

eukaryotic cells?

A. the cytoplasm

D. the nucleus

B. the mitochondrial matrix

E. the mito. intermembrane space

C. the lumen of the E.R.

123. Unlike other species, organisms that have the

Glyoxylate Cycle can

A. make fatty acids from glucose

C. make glucose from fatty acids

B. run the Citric Acid Cycle backward

D. make Acetyl CoA from fatty

acids

124. Citrate Synthase is allosterically inactivated

by what 2 compounds?

A. F 2,6 BP and CoA

D. ATP and NADHB. NADPH and Citrate


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E. ADP and Pyruvate

C. Vitamin C and Glucose

125. In the mechanism of the Pyruvate DH Complex,

Pyruvate is decarboxylated in the first step by

reacting with TPP. The cofactor responsible for

the second step is

A. ADP

D. FAD

B. NADPH

E. Ubiquinone

C. Lipoamide

126. A mixture of proteins is put through a Sephadex

column, for gel filtration. The protein which elutes

last will be

A. the most spherical

D. the most positive

B. the largest

E. the most negative

C. the smallest

127. Suppose you have a biological preparation and

you know it contains Avidin, with many otherproteins, and that Avidin binds tightly to Biotin.

What technique should you start with to purify the

Avidin?

A. affinity chromatography

D. SDS PAGE

B. dialysis

E. gel filtration

C. ultracentrifugation F. ELISA

128. Home pregnancy tests detect small traces of

the protein hCG, human chorionic gonadotropin in

the urine. What technique is this based on?

A. gel filtration

D. dialysis

B. affinity chromatography

E. SDS PAGE

C. ultracentrifugation F. ELISA

129. Which of the following would be a negative

allosteric modulator of Myoglobin?

A. 2,3 BPG

D. all of the above

B. carbon dioxide

E. Mb has no allosteric modulatorsC. H+


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130. If a solution of Hemoglobin is oxygenated to

half its capacity, what would you expect to find in

the solution?

A. only Hb(O2)2

D. mono, di, and trioxy Hb

B. half Hb, half Hb(O2)4


C. equal amounts of Hb, Hb(O2)2, and Hb(O2)4

131. Where does 2,3 Bisphosphoglycerate bind to

the Hemoglobin molecule?

A. it binds to the heme iron

D. at the opening of heme pocket

B. to the COOH end of alpha chain

E. at the center of the tetramer

C. The E helices

132. If the standard free energy change for Gal-6-P -

> Gal + Pi is 19 kJ/mol, and that for 1,3 BPG -> 3 PG

+ Pi is 49 kJ/mol, then what is the DGo' for

1,3BPG + Glu -> Glu-6-P + 3PG?

A. 68 kJ/molD. + 30 kJ/mol

B. 49 kJ/mol

E. + 68 kJ/mol

C. 30 kJ/mol

F. none of the above

133. ATP hydrolysis is a high energy process

compared to other phosphate hydrolyses because

of (choose two correct answers):

A. charge repulsion

D. quantum tunneling

B. steric hindrance

E. resonance stabilization

C. breaking a phosphate ester

134. The Second Law of Thermodynamics states that

for a spontaneous change in a system and its

surroundings, what must increase?

A. entropy

C. empathy

B. enthalpy

D. free energy

135. In the discussion of Michaelis Menten kinetics

in class, we learned that k2 (or sometimes kcat) isreferred to as


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A. the Michaelis constant

C. the turnover number

B. the gas constant

D. the catalysis constant

136. When we watch an enzyme consume substrate

over a period of time, and it produces product at a

constant rate over that entire time, we say the

reaction is

A. zero order

C. stalled

B. first order

D. steatopygeous

137. The 2-epimer of D-glucose would be

A. D-allose

D. D-ribulose

B. D-galactose

E. D-fructose

C. D-mannose

138. The structure below represents

A. stachyose

D. cellobiose

B. sucrose

E. maltose

C. lactose

139. The linkage (for example beta 1-6) of cellulose

is the same as that of

A. sucrose

D. glycogen

B. lactose

E. amylose

C. maltose

140. A glycoside of Fructose would have to be

A. a hemiacetal

D. a ketal

B. a hemiketal

E. an alpha anomer

C. an acetal

141. A camel's hump contains mostly

A. sphingolipids

D. glycogen

B. water

E. triglycerides

C. hydrophilic proteins


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142. A common fatty acid is Linoleic Acid, which has

the structure

A. 18:0

D. 18:2, D6, 9

B. 18:1 D7

E. 18:2, D9, 12

C. 18:3 D9, 12, 15

F. 16:1, D8

143. Addition of a fatty acid to sphingosine

produces a

A. ceramide

D. sphingomyelin

B. ganglioside

E. phosphatidate

C. cerebroside

144. The "fluid mosaic model" of membrane

structure concerns the fact that the lipid bilayer

membranes found in cells contain various

A. polysaccharides

D. transmembrane proteins

B. steroid dimers


C. redox cofactors

145. Integral membrane proteins have an external

"waistband" of amino acid residues which are

A. hydrophilic

D. basic

B. acidic

E. very small

C. hydrophobic

146. Stage II of Catabolism (in the Krebs scheme)

gives how much ATP?

A. none

C. a lot

B. a little

D. can't tell

147. The ratio of NADPH to NADP+ in cells is

generally kept

A. greater than one

C. less than one

B. about one

D. can't tell


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148. What is Anabolism?

A. DNA repair

D. All "energy reactions" in cell

B. building molecules


C. breaking down foods

149. Fructose 1,6 bisphosphatase is

A. inhibited by AMP, stimulated by F2,6BP

B. stimulated by AMP, inhibited by F2,6BP

C. inhibited by both AMP and F2,6BP

D. stimulated by both AMP and F2,6BP


150. Which enzyme of Gluconeogenesis is found in

the mito. matrix?

A. G6Pase

D. Pyruvate Carboxylase

B. FBPase

E. PEPCK

C. Aldolase

151. The operation of the Cori Cycle is responsible

for the appearance of what in blood?

A. Glucose-6-P, Alanine

D. Gluconolactone

B. Glucose and Lactose

E. Alanine and pyrimidines

C. Lactic Acid and Glucose

152. The reducing end of Glycogen is attached to

A. glycogenin

D. a ribosome

B. the endoplasmic reticulum

E. Fructose

C. Phosphorylase a

153. When normal glycogen is broken down by the

usual enzymes, what percentage of glucose is

released as "free" glucose?

A. 25%

D. 5%

B. 17%

E. 1%

C. 10%

F. none at all


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154. Branching enzyme produces branches by

moving how many residues of glucose?

A. 4

D. 23

B. 6 or 7

E. 42

C. 9 or 10

155. In the laboratory, Ribose-5-P and Fructose-6-P

can be reacted with the enzyme Transketolase and

the appropriate cofactor. The products observed

are:

A. Sedoheptulose-7-P and Erythrose-4-P

B. Sedoheptulose-7-P and Ribose-5-P

C. Octulose-8-P and Glyoxylate-2-P

D. Octulose-8-P and Glyceraldehyde-3-P


156. If we run five molecules of hexose (Fru-6-P or

Glu-6-P) through the nonoxidative branch of the

Pentose Phosphate Pathway, we will eventually get

A. 5 Rib-5-P and 5 NADPH

D. 6 Rib-5-P and 5 NADH

B. 5 Rib-5-P and 10 NADPH

E. 6 Rib-5-P, 5 NADPH, 5 NADH

C. 6 Rib-5-P

157. The mechanism of Transaldolase involves

covalent attachment of the substrate to the enzyme

via a residue of

A. cys

D. trp

B. lys

E. ser

C. his

158. Glutamine Synthetase is cumulatively inhibited

by several compounds including all of the

following except which one?

A. Tryptophan

D. CTP

B. Serine

E. Carbamoyl Phosphate

C. Oxaloacetate

159. Which of the following is not a cofactor

found in the pathway Phe -> Epinephrine?

A. Vitamin C


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D. B-12, cobalamin

B. SAM

E. NADPH

C. THB

160. Which amino acid is not"essential" in humans?

A. Tyrosine

D. Lysine

B. Valine

E. Methionine

C. Threonine

161. Cystathionine has how many carbons, total?

A. 3

D. 9

B. 5

E. 11

C. 7

162. If a doctor asks for an "SGOT" test, which

shows transamination of Aspartate by enzymes in

the serum, he probably suspects

A. PKU

D. gout

B. glycogen storage disease

E. sickle cell anemia

C. heart or liver damage

163. The compound shown below represents

A. N5 Formyl THF

D. N5 N10 Methenyl THF

B. N10 Formyl THF

E. N5 Methyl THF

C. N5 N10 Methylene THF

164. Phenylalanine can't be made by human cells but

is easily made by certain other species. The starting

materials for Phe synthesis are

A. R5P and S7P

D. OAA and Pyruvate

B. E4P and PEP

E. Glu and PLP

C. Alanine and Benzene

165. Lack of Phenylalanine Mono-oxygenase ("Phe

Hydroxylase") can cause

A. Gout

D. Lesch-Nyhan Syndrome

B L E C P


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B. Leukemia


C. Phenylketonuria

166. The synthesis of Urea requires how many ~P,

high energy P-bonds?

A. 2

C. 6

B. 4D. 8

167. Drugs like Methotrexate prevent synthesis of

DNA by binding to

A. DNA Pol I

D. Thymidylate Synthase

B. DNA Pol III

E. Reverse Transcriptase

C. Dihydrofolate Reductase

168. Conversion of Xanthylate (XMP) to Guanylate

(GMP) is blocked by

A. azaserine

D. low Aspartate

B. methotrexate

E. low Carbamoyl Phosphate

C. high NADPH levels

169. Ribonucleotide Reductase makes use of an

unusual cofactor:

A. biotin

D. Thioredoxin

B. FMNH2 E. Thiamine

C. B-12

170. The pyrimidine ring is built from carbamoyl

aspartate and which amino acid?

A. asparagine

D. threonine

B. alanine

E. aspartate

C. glutamate

171. During Pyrimidine biosynthesis, first the ring is

built and then it undergoes a "salvage" reaction

with PRPP. Which intermediate reacts with PRPP?

A. Uridine

D. Thymine

B. Dihydroorotate

E Guanine E Ca++ regulates the contraction process by


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E. Guanine

C. Orotate

172. If [ATP]= 10 mM, [ADP]= 6 mM, and [AMP] = 4 mM,

what is the energy charge in the cell?

A. 26

D. 0.80

B. 1.0

E. 0.65C . 0.88

F. 0.50

173. All of the following are true of skeletal

muscle contraction EXCEPT

A. ATP binds to myosin and causes myosin to detach

from actin

B. Myosin catalyzes the reversible hydrolysis of

ATP at the catalytic site but the products remain

tightly bound to the enzyme until actin binds and

displaces phosphate

C. The myosin-ADP-actin complex undergoes a

conformation change with release of ADP

D. The power stroke in muscle contraction occurs

when the myosin headpiece re-attaches to actin

E. Ca++ regulates the contraction process by

allowing the myosin-ADP-Pi complex to interact with

actin filaments

174. Malignant hyperthermia occurs in 1:20,000

surgical procedures where muscle relaxants and

general inhalation anesthetics are used. Malignant

hyperthermia is caused by:

A. an uncoupling of oxidative phosphorylation inmuscle mitochondria by the anesthetics

B. stimulation of Na+-K+ ATPase activity

C. the formation of stable myosin-actin

crossbridges that cannot be broken by ATP

D. an elevated level of intracellular Ca++ that

promotes continuous muscle contraction with

associated increased ATP hydrolysis and oxidative

phosphorylation

E. the depolymerization of F-actin to produce G-

actin

175. Microtubules are involved in

A. cell division

B. ciliar and flagellar movement

C. movement of secretory vesicles along axons

D. movement of organelles within cells

E all of the above E muscle waste hypertension and a beard


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E. all of the above

176. Muscle proteolysis is accompanied by the

release of ala and gln from muscle. What is the

carbon source of these amino acids?

A. muscle protein, because it has a high content of

ala and gln

B. glucose

C. creatinineD. glycerol

E. acetoacetate

177. A female patient with Cushings disease is

distinguishable by

A. low plasma ACTH, urinary 17a-

hydroxycorticosteroids > 100 mg/day and urinary

17-ketosteroids < 12 mg/day

B. high plasma ACTH, urinary 17a-

hydroxycorticosteroids >

100 mg/day and urinary 17-ketosteroids > 12

mg/day

C. high plasma angiotensin II, low urinary Na+ and

low urinary tetrahydroaldosterone

D. high plasma ACTH, urinary 17-ketosteroids > 17

mg/day and urinary estrogen > 60 mg/day

E. muscle waste, hypertension and a beard

178. A patient with secondary aldosteronism will

display

A. high serum Na+, high serum aldosterone and no

serum renin

B. high serum Na+, high serum renin, low serum

aldosterone

C. hypertension and elevated serum reninD. no serum ACTH, no serum aldosterone and high

serum Na+

E. masculinization and hypertension

179. A patient with Familial Hypercholesterolemia

has a defect in the clustering of LDL receptors in

coated pits. Incubation of this patient's fibroblasts

with 125ILDL for 1 hour will result in

A. most of the 125I-LDL being internalized in the

cells

B. most of the 125I-LDL being degraded

C. most of the 125I-LDL being bound to the surface

of the cells

D. most of the 125I-LDL being converted to 125I-

VLDL

E most of the 125I-LDL undergoing lysosomal E a decreased ability to convert VLDL to IDL


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E. most of the 125I-LDL undergoing lysosomal

digestion

180. In relation to hepatic cells from a normal

person on a low animal fat diet, hepatic cells from a

normal person on a prolonged high animal fat diet

will

A. contain higher amounts of cholesterol

B. contain a lower number of LDL receptorsC. contain a less active HMG-reductase

D. contain fewer mRNAs for the LDL receptor

E. all of the above are correct

181. A person with type IIA hyperlipoproteinemia

(Familial Hypercholesterolemia) had a blood

cholesterol level of 360 mg/dl (recommended

level below 200 mg/dl) and a blood triglyceride

(triacylglycerol) level of 140 mg/dl (recommended

level below 160 mg/dl). This person most likely has

A. a decreased ability for receptor-mediated

endocytosis of LDL

B. a decreased ability to degrade the

triacylglycerols of chylomicrons

C. an increased ability to produce VLDL

D. an elevation of HDL in the blood

E. a decreased ability to convert VLDL to IDL

182. A person with an LDL-receptor deficiency was

treated with lovastatin. As a consequence of the

action of this drug, the person should have

A. fewer LDL receptors in cell membranes

B. increased de novo cholesterol synthesis

C. increased LCAT activity

D. lower blood cholesterol levelsE. higher blood triacylglycerol levels

183. A patient with hyperlipoproteinemia would be

most likely to benefit from a low-carbohydrate diet

if the lipoproteins that are elevated in the blood

are

A. chylomicrons

B. VLDL

C. LDL

D. HDL2

E. HDL3

184. The liver does not accumulate excessive

amounts of cholic and chenodeoxycholic acids

because

A these bile acids are totally excreted from the E the effects of excess DHEA and hypertension as


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A. these bile acids are totally excreted from the

intestine

B. high levels of cholic acid will block directly

HMGreductase

C. high levels of these bile acids will block 7a-

hydroxylase

D. these bile acids will be incorporated into VLDL

and passed into the plasma

E. excess levels of the precursors of cholesterol

will be converted instead into steroid hormones

185. A young female patient suffering from an

adrenogenital syndrome characterized by an

inactive 11b-hydroxylase will display

A. the effects of excess glucocorticoids and

hypertension as well as high levels of

tetrahydrocortisol in the urine

B. the effects of excess androgens and

hypertension as well as high levels of pregnanediol

and pregnanetriol in the urine

C. the effects of excess androgens and

hypertension as well as high levels of

tetrahydroaldosterone in the urine

D. the effects of excess androgens and high levels

of salt in the urine

E. the effects of excess DHEA and hypertension as

well as high salt in the urine

Choose the single best answer for the following

questions. 6

186. In a fasting person, glucagon will affect the

de novo synthesis of cholesterol in liver

A. by bringing about the phosphorylation ofHMGreductase which deactivates this enzyme

B. by bringing about the phosphorylation of HMG-

reductase which activates this enzyme

C. by increasing the level of acetyl CoA

D. by increasing gluconeogenesis

E. by bringing about the dephosphorylation of

HMGreductase which deactivates this enzyme

187. A new drug "zaragozic acid" is now available

which blocks the squalene synthetase system and

therefore dramatically lowers the plasma

cholesterol levels in hypercholesterolemia

patients. Lovastatin, which completely blocks

HMG-reductase, lowered cholesterol plasma levels

in these patients to a similar degree. Would you

prefer to prescribe

A. lovastatin because it will cause an increase in


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A. lovastatin because it will cause an increase in

HMG-CoA which can be metabolized to ketone bodies

B. lovastatin because it will permit the synthesis of

isoprene units

C. lovastatin because it will increase the synthesis

of squalene

D. zaragozic acid because it will not block the

synthesis of isoprene units and farnesyl

pyrophosphate

E. zaragozic acid because it will not prevent thesynthesis of 7-dehydrocholesterol, a vitamin D3

precursor

188. Lymphocytic leukemia can become resistant to

treatment by glucocorticoids or glucocorticoid

drugs because

A. these cells can metabolize certain

glucocorticoids to inactive metabolites

B. these cells can lose the expression of the

glucocorticoid receptor

C. the glucocorticoid receptor may become mutated

so that the receptor complex no longer interacts

properly with its responsive element

D. these cells may more actively convert cortisol

to cortisone


189. In a normal person, hypertension is prevented

because the kidney tubule cell contains

A. only an aldosterone specific receptor

B. an inactive 21-hydroxylase

C. a high affinity 11b-hydroxysteroid dehydrogenase

D. 17b-hydroxysteroid dehydrogenase

E. peripheral aromatase

190. A postmenopausal patient presents with a

breast tumor. Proteins in the cytosol from a

homogenate of a biopsy of this tumor display high

affinity, specific binding of tritriated estradiol and

tritriated progesterone. Treatment of this patient

with an antihormone such as tamoxifen is warranted

because

A. the tumor is hormone dependent (responsive)

B. the tumor contains active estrogen receptor

C. an estrogen regulated gene is turned on

D. the patient is postmenopausal


191. It is also reasonable to treat this patient with

A. diethylstilbesterol (DES)

B. CGP-47,645 E. all of the above are correct


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,

C. spironolactone

D. finasteride

E. MER-25

192. A patient with prostate cancer responded best

when he was treated with a combination of

flutamide and finasteride. An analysis of this tumor

before treatment would be expected to show the

presence of

A. aromatase and lutenizing hormone (LH) receptor

B. desmolase and 17,20-lyase

C. androgen receptor and 5a-reductase

D. only the androgen testosterone

E. both the androgen and glucocorticoid receptors


questions. 9

193. The nuclear DNA from this prostate tumor

would be expected to contain

A. mutated Zn-fingers

B. NF-kB

C. Ras-GTP

D. the appropriate hormone response element (HRE)

upstream of responsive genes

194. Ovarian follicular growth in a patient is best

measured by

A. the level of plasma ACTH

B. the level of plasma LH

C. the urinary level of 17-ketosteroids

D. the urinary level of progesterone (pregnanediol)

E. the urinary level of estriol

195. A patient is having difficulty conceiving. An

analysis of her plasma shows that the level of FSH

is low and the level of estrogen is constantly high.

Her pituitary function is normal and, other than

hypersecretion of androstenes, her ovary is

normal. Ovulation can be induced in this patient by

administering for a short period (5 days)

A. lutenizing hormone

B. an antiestrogen

C. progesterone

D. RU-486

E. prolactin


questions. 10

196. Important to the control of steroid hormone E. increased lipogenesis and increased glycogen


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synthesis by ACTH, LH or FSH is the fact that

A. high levels of cholesterol will downregulate

the LDL receptor

B. phospholipase A2 hydrolyzes arachidonate from

membrane phospholipids

C. desmolase resides in the mitochondria

D. all three of these polypeptides are bound by the

same membrane receptorE. the steroid hormone secreted by the endocrine

tissue cannot down regulate the secretion of

ACTH, LH or FSH

196. Hyperglycemia in patients with diabetes

mellitus results from which of the following?

A. increased lipolysis in adipose tissue and skeletal

muscle

B. increased hepatic gluconeogenesis and

decreased

glycolysis in adipose tissue and skeletal muscle

C. decreased proteolysis and increased lipolysis in

adipose tissue

D. increased glycogen synthesis and decreased

glycogenolysis in adipose tissue and skeletal

muscle

synthesis in adipose tissue and skeletal muscle

197. The acidosis of diabetic ketoacidosis results

from which of the following?

A. increased lipolysis in adipose tissue resulting

from increased lipoprotein lipase activity

B. increased lipolysis in adipose tissue resulting

from increased hormone sensitive triglyceridelipase activity

C. increased lipolysis in adipose tissue resulting

from increased monoglyceride lipase activity in

hepatocytes

D. increased glycolysis due to increased glycogen

phosphorylase a activity in adipose tissue and

skeletal muscle

E. increased glycolysis resulting from increased

phosphofructokinase activity in liver and skeletal

muscle

198. Elevated levels in blood following severe

crushing injury can lead to renal

damage

199. Urinary levels are used as a marker for muscle

proteolysis

203. An agonist binding to its membrane receptor


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A. succinyl CoA

B. succinyl choline

C. creatinine

D. 3-methyl histidine

E. dystrophin

F. myoglobin

200. Low serum Ca++ (< 10 mg %) and normal serum

phosphate will normally be accompanied by

201. Low serum phosphate and normal serum Ca++

will be normally accompanied by

202. Analysis of serum from a patient with x-linked

hypophosphatemia will display

A. elevated serum levels of PTH, elevated serum

levels of 1a,25(OH)2 Vit D3

B. elevated serum levels of PTH, low serum levels

of 1a,25(OH)2 Vit D3

C. low serum levels of PTH, high serum levels of

1a,25(OH)2 Vit D3

D. low serum levels of PTH, low serum levels of

1a,25(OH)2 Vit D3


brings about GDP.Ga,bg , + GTP -> Gb,g + GDP +

GTP.Ga which initiates


brings about the activation of phospholipase A2

which initiates


brings about the activation of tyrosine kinase whichinitiates

A. the metabolic formation of diacylglycerol which

activates protein kinase A

B. the activation of Ras and the hydrolysis of

arachidonate from position 2 of a phospholipid

C. the activation of Ras which ultimately brings

about the phosphorylation of nuclear regulatory

proteins

D. the binding of Ca++ to calmodulin which

activates cyclooxygenase

E. the metabolic formation of cAMP which activates

protein kinase C

F. the formation of and binding of cAMP to an

enzyme protein

G. the hydrolytic production of a substrate for

Cyclooxygenase.

E) It indicates that binding affinity increases as more


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206. Which of the following statements about fetal

hemoglobin is not correct?

A) Fetal hemoglobin has higher affinity for O2 than

maternal hemoglobin A

B) Fetal hemoglobin has fewer positive charged

amino acids at g-globin C-terminal

C) Fetal hemoglobin binds 2,3-bisphosphoglycerate

more stronglyD) The sigmoidal O2 binding curve of fetal

hemoglobin is shifted to the left

E) Fetal hemoglobin remains in R-state at lower pO2

207. Which of the following statements about the

sigmoidal O2 binding curve of hemoglobin is not

correct?

A) Transition from almost empty to almost full

occurs over a narrower range of pressures

B) It allows for more efficient release of O2 at pO2

found in peripheral tissues

C) Hemoglobin has higher P50 than myoglobin, but

still reaches saturation at the same pO2 as

myoglobin

D) It allows more O2 to bind to hemoglobin than to

myoglobin at any given pO2

sites are occupied

208. Which of the following correctly describes

how CO2 interacts with hemoglobin?

A) CO2 binds to heme Fe2+

B) CO2 binds to heme Fe3+

C) CO2 binds to His F8

D) CO2 binds to His E7E) CO2 binds to the N-terminal of a-globin

209. Which of the following does not play a role in

the blood clotting cascade?

A) Fibrinogen

B) Prothrombin

C) Protein kinase A

D) Factor Xa

E) Factor VIII

210. Which of the following enzymes is directly

involved in production of NADPH?

A) Lactate dehydrogenase

B) Glyceraldehyde-3-phosphate dehydrogenase

C) Pyruvate dehydrogenase

D) Glucose-6-phosphate dehydrogenase A) Phosphorylase a preferentially goes to the


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E) Phosphofructokinase

211. Which of the following is responsible for

activating Protein kinase A?

A) Cyclic AMP binds to R subunits of protein kinase A

B) Cyclic AMP binds to C subunits of protein kinase

A

C) Cyclic AMP becomes available as phosphatedonor

D) Cyclic AMP is hydrolyzed to 5'-AMP

E) The proenzyme form is cut by proteolysis

212. If Cyclin E-Cdk2 activates DNA replication

proteins , at what phase of the cell cycle does its

activity come to a peak?

A) Progression through G1

B) Entry to S phase

C) Entry to G2 phaseD) Progression through G2 phase

E) Entry and progress through M phase

213. Which of the following statements about

phosphorylase ais not correct?

active R state

B) Phosphorylase a phosphorylates enzymes

involved in glycogen

metabolism

C) Phosphorylase ais converted to phosphorylase b

by phosphoprotein phosphatase 1

D) Phosphorylase a is negatively regulated by

glucose.

E) Serine 14 of phosphorylase ais phosphorylated

214. Which hemoglobin form is expressed during

months 2-9 of pregnancy?

A) zzbb

B) eebb

C) aagg

D) aadd

E) eegg

215. Which of the following correctly describesthe role of tissue plasminogen activator?

A) promotes clotting by activating fibrinogen

B) promotes clotting by activating prothrombin

C) prevents clotting by binding to fibrinogen

D) prevents clotting by binding to prothrombin

E) promotes the dissolution of clots C) Fructose-1,6-bisphosphatase


38/39

216. Which of the processes for activation of

pancreatic proenzymes is not correct?

A) Enteropeptidase can activate trypsinogen

B) Trypsin can activate trypsinogen

C) Chymotrypsin can activate trypsinogen

D) Trypsin can activate

chymotrypsinogenE) Trypsin can activate Procarboxypeptidase

217. What is the mechanism by which caffeine

stimulates glycogen breakdown?

A) Caffeine inhibits breakdown of cyclic AMP

B) Caffeine is an allosteric activator of glycogen

phosphorylase

C) Caffeine inhibits phosphoprotein phosphatase

D) Caffeine binds to protein kinase A

E) Caffeine stimulates production of cyclic AMP

218. Which of the following enzymes is not required

for gluconeogenesis in liver?

A) PEP carboxykinase

B) Pyruvate carboxylase

D) Pyruvate kinase

E) Glucose-6-phosphatase

219. Which of the following is the initiator

procaspase activated by external signals such as

tumour necrosis factor?

A) Procaspase 1

B) Procaspase 3C) Procaspase 7

D) Procaspase

8 E) Procaspase 9

220. How many steps in the gluconeogenesis

pathway yield ATP as a product?

A) 0

B) 1

C) 2

D) 4E) 6

221. If transketolase accepts xylulose-5-phosphate

and erythrose-4-phosphate as substrate, what

products are released?

A) Sedoheptulose-7-phosphate and glyceraldehyde- D) 5'-AMP level is controlled by


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3-phosphate

B) Fructose-6-phosphate and glyceraldehyde-3-

phosphate

C) Ribulose-5-phosphate and glyceraldehyde-3-

phosphate

D) Dihydroxyacetone-3-phosphate and glucose-6-

phosphate

E) Dihydroxyacetone-3-phosphate and ribose-5-

phosphate

222. What are the characteristics of hemoglobin

variant bbbb produced in a-thalassemia?

A) It binds O2 like normal hemoglobin B) It binds O2

like fetal hemoglobin

C) It is unable to bind O2 D) It binds O2 like

myoglobin

E) It polymerizes into fibres in red blood cells

223. Which of the following properties is directlyrelated to the concentration of 5'-AMP as an

indicator of energy status ?

A) 5'-AMP level is correlated with high [ATP]

B) 5'-AMP level is correlated with [ADP]

C) 5'-AMP level is controlled by external hormones

phosphofructokinase 2

E) 5'-AMP level is correlated with the square of

[ADP]

224. Which of the following is used as substrate by

glycogen synthase?

A) UTP-Glucose

B) UDP-GlucoseC) Glucose-1-phosphate

D) Glucose-6-phosphate

E) Glucose + ATP

225. What compound is exported from mitochondria

to provide substrate gluconeogenesis in the

cytoplasm when lactate is the starting point?

A) Pyruvate

B) Malate

C) OxaloacetateD) PEP E) Acetyl CoA

Biochem-mcq-GATE

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