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Biochemisty Main > 2nd Biochemistry Lecture Exam (Batch 2026) > Flashcards

2nd Biochemistry Lecture Exam (Batch 2026) Flashcards

1
Q

1.ELISA was developed from modification of RIA. This method was first employed to determine?
A. Thyroid levels in blood
B. HCG in urine
C. FSH in breast milk
D. Influenza in saliva

A

B. HCG in urine

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2
Q

2.This type of ELISA utilizes two specific antibodies; an enzyme conjugated antibody and an antibody in the serum?
A. Direct
B. Indirect
C. Sandwich
D. Competitive

A

D. Competitive

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3
Q

3.This type of ELISA utilizes an antigen coated-plate and a screening antigen or antibody?
A. Direct
B. Indirect
C. Sandwich
D. Competitive

A

B. Indirect

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4
Q

4.Which of the following factors may interfere with the antibody capture and detection resulting to inappropriate ELISA testing?
A. Material of the plate
B. Cross reactivity
C. Titer and affinity
D. Conformation, stability

A

C. Titer and affinity

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5
Q

5.The result and reporting that will deny or confirm the presence of a particular antigen/ antibody in a sample?
A. Quantitative
B. Qualitative
C. Semiqualitative
D. Semiquantitative

A

B. Qualitative

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6
Q

6.The use of Aspariginase in patients with ALL may be limited due to its toxicity that may be severe?
A. Hypersensitivity reaction
B. Anaphylaxis
C. Pancreatitis
D. Coagulation abnormalities

A

B. Anaphylaxis

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7
Q

7.During the treatment with Aspariginase, malignant cells are unable to produce asparagine due to?
A. High number of destroyed cells
B. Increase amount of substrate
C. Lack of synthase
D. Inhibition from normal cells

A

C. Lack of synthase

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8
Q

8.Newer asparaginase of which the toxicity is reduced are derived from?
A. E. coli
B. E. chrysantemi
C. E. elspar
D. E. histolytica

A

B. E. chrysantemi

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9
Q

9.Tripsinogen are members of the pancreatic enzymes whos function are?
A. Proteolytic
B. Amylolitic
C. Lipolitic
D. Hydrolitic

A

A. Proteolytic

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10
Q

10.Efficacy of endogenous pancreatic enzymes are reduced by?
A. Low pH
B. Bicarbonates
C. Small intestinal secretion
D. Esophageal actions

A

A. Low pH

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11
Q

11.In determining the absolute quantity of enzyme, which of the following factors will increase the amount of enzyme?
A. ↑ rate of synthesis, ↓ rate of degradation
B. ↑ rate of synthesis, ↑ rate of degradation
C. ↓ rate of synthesis, ↓ rate of degradation
D. ↓ rate of synthesis, ↑ rate of degradation

A

A. ↑ rate of synthesis, ↓ rate of degradation

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12
Q
  1. Kinases require binding to Magnesium (Mg+) ion. Magnesium is an example of:
    A. Co-factor
    B. Co-enzyme
    C. Co-substrate
    D. Co-repressor
A

A. Co-factor

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13
Q

13.Which of the following correctly represents the mechanism of enzyme function:
A. S+P → S-P → E-P → E+P
B. E+P → E-P → E-S → E+S
C. E+P→ E-S → E-P → E+P
D. E+S→ E-S → E-P → E+P

A

D. E+S→ E-S → E-P → E+P

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14
Q

14.Some enzymes are catalytic RNA molecules. These are called:
A. Apoenzymes
B. Holoenzymes
C. Ribozymes
D. Abzymes

A

C. Ribozymes

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15
Q

15.Antibodies that possess catalytic properties are called:
A. Apoenzymes
B. Holoenzymes
C. Ribozymes
D. Abzymes

A

D. Abzymes

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16
Q

16.The following enzymes are of diagnostic use for Myocardial infarction EXCEPT:
A. Acid phosphatase
B. Aminotransferase
C. Creatine Kinase
D. Lactate dehydrogenase

A

A. Acid phosphatase

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17
Q

17.Amylase and lipase are enzymes that can used to diagnose:
A. Viral hepatitis
B. Acute pancreatitis
C. Myocardial infarction
D. Wilson’s disease

A

B. Acute pancreatitis

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18
Q

18.Which of the following statements regarding enzymes is TRUE:
A. Enzymes are consumed during chemical reactions.
B. Without enzymes, metabolic reactions will not occur.
C. Enzymes catalyze only one type of chemical reaction
D. Enzymes selectively channel products into useful pathways

A

C. Enzymes catalyze only one type of chemical reaction

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19
Q

19.These enzymes are also known as dehydrogenases
A. Hydrolase
B. Lyase
C. Ligase
D. Oxido-reductase

A

D. Oxido-reductase

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20
Q

20.Digestive enzymes such as Amylase, Cellulase and Sucrase belong to this class of enzymes.
A. Hydrolase
B. Lyase
C. Ligase
D. Oxido-reductase

A

A. Hydrolase

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21
Q

21.This class of enzyme follows this typical reaction: AB + H2O → AOH +BH
A. Hydrolase
B. Lyase
C. Ligase
D. Oxido-reductase

A

A. Hydrolase

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22
Q

22.What class of enzymes catalyzes removal of a functional group from a substrate and cleavage of covalent bonds without the addition of water
A. Hydrolase
B. Lyase
C. Ligase
D. Oxido-reductase

A

B. Lyase

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23
Q

23.Glucose 6-phosphate is converted to Fructose 6-phosphate with an enzyme that belongs to which class of enzymes?
A. Transferase
B. Isomerase
C. Ligase
D. Oxido-reductase

A

B. Isomerase

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24
Q

24.Pyruvate carboxylase converts Pyruvate and CO2 to Oxaloacetate in the presence of ATP. Pyruvate carboxylase is classified as a/an:
A. Transferase
B. Isomerase
C. Ligase
D. Oxido-reductase

A

C. Ligase

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25
Q

25.Glucose + ATP is converted to Glucose-6-phospate + ADP. The enzyme responsible for this belongs to this class of enzymes
A. Transferase
B. Isomerase
C. Ligase
D. Oxido-reductase

A

A. Transferase

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26
Q

26.The functional groups of an active site are:
A. Binding site and catalytic site
B. Binding site and substrate site
C. Catalytic site and substrate site
D. Binding site, catalytic site and substrate site

A

A. Binding site and catalytic site

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27
Q

27.Which of the following represents the mechanism in catalysis by proximity:
A. ↑ concentration , ↑ interaction, ↑ rate of reaction
B. ↑ concentration , ↑ interaction, ↓ rate of reaction
C. ↑ concentration , ↓ interaction, ↓ rate of reaction
D. ↓ concentration , ↓ interaction, ↑ rate of reaction

A

A. ↑ concentration , ↑ interaction, ↑ rate of reaction

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28
Q

28.Ping-pong mechanism is an example of which type of catalysis
A. Catalysis by proximity
B. Acid-base catalysis
C. Catalysis by strain
D. Covalent catalysis

A

D. Covalent catalysis

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29
Q

29.What is the most significant property of an enzyme?
A. Specificity
B. Active Site
C. Catalytic efficiency
D. Enzyme Regulation

A

A. Specificity

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30
Q

30.Which enzyme exemplifies absolute specificity?
A. Glucosidase
B. Esterase
C. Pepsin
D. Urease

A

D. Urease

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31
Q

31.An enzyme activity can be increased or decrease through these general mechanisms EXCEPT:
A. Change the absolute quantity of the enzyme present
B. Change the number of product converted to a substrate
C. Alter the pool size of the reactants
D. Alter the catalytic effect of the enzyme

A

B. Change the number of product converted to a substrate

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32
Q

32._____________ is an active enzyme complete with its non-protein component
A. Apoenzyme
B. Holoenzyme
C. Ribozyme
D. Abzyme

A

B. Holoenzyme

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33
Q

33.Co-enzymes include the following EXCEPT:
A. Fe
B. FAD
C. FMN
D. NADP

A

A. Fe

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34
Q

34.The number of molecules of substrate converted to product per enzyme molecule per second is called:
A. Turnover number
B. Enzyme turnover
C. Kcat
D. Both A and C

A

D. Both A and C

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35
Q

35.The following enzyme activities are found in the mitochondria:
A. Fatty acid oxidation and tricyclic acid cycle
B. Glycolysis and HMP pathway
C. DNA and RNA synthesis
D. Degradation of complex macromolecules

A

A. Fatty acid oxidation and tricyclic acid cycle

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36
Q

36.Which of the following statements about the active site of an enzyme is correct?
a. The active site of an enzyme binds the substrate of the reaction it catalyses more tightly than it does the transition state intermediate
b. The active site of an enzyme binds the substrate of the reaction it catalyses less tightly than it does the transition state intermediate
c. The active site of an enzyme binds the product of the reaction it catalyses more tightly than it does the transition state intermediate.
d. The active site of an enzyme is complementary to the substrate of the reaction it catalyses

A

b. The active site of an enzyme binds the substrate of the reaction it catalyses less tightly than it does the transition state intermediate

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37
Q

37.Which of the following statements about the nature of enzyme catalysis is correct?
a. An enzyme can change the equilibrium position of the reaction it catalyses by lowering the energy of activation of that reaction.
b. An enzyme can lower the energy of activation of the reaction it catalyses by increasing the molecular collisions between the molecules.
c. An enzyme lowers the free energy difference between substrate(s) and product(s) but it cannot change the equilibrium position of the reaction it catalyses.
d. An enzyme cannot change the equilibrium position of the reaction it catalyses but it lowers the energy of activation of that reaction.

A

d. An enzyme cannot change the equilibrium position of the reaction it catalyses but it lowers the energy of activation of that reaction

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38
Q

38.Which of the following statements about Michaelis-Menten kinetics is correct?
a. Km, the Michaelis constant, is defined as the concentration of substrate required for the reaction to reach maximum velocity
b. Km, the Michaelis constant, is defined as the dissociation constant of the enzyme-substrate complex
c. Km, the Michaelis constant, is expressed in terms of the reaction velocity
d. Km, the Michaelis constant, is a measure of the affinity the enzyme has for its substrate

A

d. Km, the Michaelis constant, is a measure of the affinity the enzyme has for its substrate

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39
Q

39.Which of the following statements about competitive inhibition of an enzyme-catalyzed reaction is correct?
A. A competitive inhibitor and substrate can bind simultaneously to the enzyme
B. The Vmax and Km (Michaelis constant) for a reaction are unchanged in the presence of a competitive inhibitor.
C. The Vmax for a reaction remains unchanged in the presence of a competitive inhibitor.
D. The Km for a reaction remains unchanged in the presence of a competitive inhibitor.

A

B The Vmax and Km (Michaelis constant) for a reaction are unchanged in the presence of a competitive inhibitor.

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40
Q

40.Which of the following statements about the mechanism of allosteric control of enzyme activity is correct?
a. Allosteric enzymes are typically single-subunit enzymes.
b. Allosteric enzymes show greater sensitivity to changes in substrate concentration compared to classical type enzymes with hyperbolic kinetics.
c. Allosteric enzymes show Michaelis-Menten kinetics.
d. Allosteric enzymes show reduced sensitivity to changes in substrate concentration compared to classical type enzymes with hyperbolic kinetics.

A

b. Allosteric enzymes show greater sensitivity to changes in substrate concentration compared to classical type enzymes with hyperbolic kinetics.

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41
Q

41.Which of the following statements about the nature of enzyme catalysis is correct?
a. The rate of formation of the transition state intermediate determines the overall free energy change of the reaction.
b. The active site of an enzyme is perfectly complementary to the substrate in its ground state.
c. The rate of formation of the transition state intermediate determines the overall reaction rate.
d. Natural substrates bind to enzymes more tightly than transition state analogues.

A

c. The rate of formation of the transition state intermediate determines the overall reaction rate.

42
Q

42.Which of the following statements about non-competitive inhibition of an enzyme-catalyzed reaction is correct?
a. The addition of large amounts of substrate to a reaction cannot overcome the effect of a non-competitive inhibitor.
b. A non-competitive inhibitor can bind to the enzyme-substrate complex.
c. Non-Competitive inhibition can be overcome by the addition of large amounts of substrate to a reaction.
d. The Vmax of a reaction is unchanged in the presence of a non-competitive inhibitor.

A

a. The addition of large amounts of substrate to a reaction cannot overcome the effect of a non-competitive inhibitor.

43
Q

43.Which of the following statements about Lineweaver-Burk plots are correct?
a. All enzyme-catalysed reactions give a linear Lineweaver-Burk plot.
b. A Lineweaver-Burk plot provides estimates of Vmax and Km for allosteric enzymes.
c. it is the reciprocal of the Michaelis Menten equation
d. A Lineweaver-Burk plot for a classical enzyme can provide estimates of Vmax and Kd by linear extrapolation.

A

c. it is the reciprocal of the Michaelis Menten equation

44
Q

44.Which of the following statements about Michaelis-Menten kinetics are correct?
a. A high Michaelis constant (Km) indicates a high affinity of an enzyme for its substrate.
b. A low Michaelis constant (Km) indicates a high affinity of an enzyme for its substrate.
c. The Michaelis constant (Km) of an enzyme increases when the enzyme concentration is increased.
d. The Michaelis constant (Km) of an enzyme is decreases when the enzyme concentration is increased.

A

b. A low Michaelis constant (Km) indicates a high affinity of an enzyme for its substrate.

45
Q

45.Which of the following statements about Michaelis-Menten kinetics are correct?
a. Michaelis-Menten kinetics assume covalent binding occurs between enzyme and substrate.
b. Michaelis-Menten kinetics assume the enzyme and substrate first bind to form an enzyme-substrate complex.
c. Michaelis-Menten kinetics describe multiple substrate enzymes.
d. Michaelis-Menten kinetics apply only to reaction rates before the product is formed.

A

b. Michaelis-Menten kinetics assume the enzyme and substrate first bind to form an enzyme-substrate complex.

46
Q

46.Which of the statements regarding enzymes is false?
a. enzymes are specific
b. enzymes may be used many times for a specific reaction
c. Enzymes are proteins that function as catalysts.
d. Enzymes provide activation energy for reactions.

A

d. Enzymes provide activation energy for reactions.

47
Q

47.The catalytic activity of two different enzymes can be compared by the:
a. Km value
b. pH of optimum value
c. molecular size of the enzyme
d. formation of the product.

A

a. Km value

48
Q

48.The active site of an enzyme differs from an antibody-antigen binding site in that the enzyme active site
a. is complementary to a specific ligand.
b. contains amino acids without sidechains.
c. catalyzes a chemical reaction.
d. contains modified amino acids.

A

c. catalyzes a chemical reaction.

49
Q

49.The transition state of a catalyzed reaction is:
a. lowering energy than that of an uncatalyzed reaction
b. lower in energy than the reaction substrate
c. bound very weakly to the catalyst.
d. a highly-populated intermediate on the reaction pathway

A

a. lowering energy than that of an uncatalyzed reaction

50
Q

50.The substrate Km in an enzyme-catalyzed reaction:
a. is usually less than Kd, the dissociation constant.
b. be equal to Kd
c. never less than Kd
d. estimated from the Y-intercept of a Lineweaver-Burk plot.

A

c. never less than Kd

51
Q

51.Enzymes that have NAD+ or NADH as a substrate follows
A, Michealis Menten Kinetics
B. Sequential Ordered
C. Sequential Random
D. Pingpong

A

B. Sequential Ordered

52
Q

52.Free energy of activation:
a. Energy difference between that of the reactant and transition state a high energy intermediate that occurs during the formation of product
b. Energy difference between that of the reactant and transition state a low energy intermediate that occurs during the formation of product
c. Energy difference between that of the reactant and transition state a high energy intermediate that occurs before the formation of product
d. Energy difference between that of the reactant and transition state a high energy intermediate that occurs after the formation of product

A

a. Energy difference between that of the reactant and transition state a high energy intermediate that occurs during the formation of product

53
Q

53.The Substrate velocity curve illustrates that:
a. Rate or velocity of a reaction is the number of substrate molecules converted to product per unit time.
b. decreases with substrate concentration until a maximal velocity is reached
c. Maximal Velocity occurs because the enzymes are consumed in the reaction process
d. increases with substrate concentration with no maximal velocity.

A

a. Rate or velocity of a reaction is the number of substrate molecules converted to product per unit time.

54
Q

54.An example of a sequential random reaction:
A. Formation of phosphocreatine and ADP from ATP and creatine
B. Lactate Dehydrogenase reduces pyruvate to lactate
C. enzyme aspartate aminotransferase catalyzes the transfer of an amino group from aspartate to alpha-ketoglutarate
D. All of the above

A

A. Formation of phosphocreatine and ADP from ATP and creatine

55
Q

55.The Bell shape of the activity-ph profile results from:
A. amino acid residues with ionizable groups in the side chain are essential for catalysis
b. enzymes being denatured at different temperatures
c. enzymes act optimally at different ph levels
d. All of the above

A

A. amino acid residues with ionizable groups in the side chain are essential for catalysis

56
Q

56.Why is the alpha carbon of most amino acids chiral?
A. has no net charge.
B. is a carboxylic acid.
C. is bonded to four different chemical groups.
D. is in the L absolute configuration in naturally occurring proteins.

A

D. is in the L absolute configuration in naturally occurring proteins

57
Q

57.Which of the amino acids is not an optically active, and why?
A. alanine; is a simple methyl group
B. glycine; hydrogen atom as a functional group
C. glycine; is unbranched
D. lysine; contains only nitrogen

A

B. glycine; hydrogen atom as a functional group

58
Q

58.Which of the 20 common amino acids has its sulfur atom bonded to carbons thru a thio ether link?
A. cysteine
B. cystine
C. methionine
D. S-adenosylmethionine

A

C. methionine

59
Q

59.Which of the common a amino acids usually forms part of the active site of enzyme?
A. arginine
B. lysine
C. tyrosine
D. histidine

A

D. histidine

60
Q

60.Which of the aromatic amino acids is responsible for the proteins’ absorbance at 280nm?
A. phenylalanine
B. tyrosine
C. tryptophan
D. proline

A

C. tryptophan

61
Q

61.Which functional group is always present in the N-terminus of proteins?
A. amino group
B. carbonyl group
C. carboxyl group
D. ester group

A

C. carboxyl group

62
Q

62.What is the name of the R group of glutamate?
A. α amino
B. β carboxylic
C. ε amino
D. γ carboxylic

A

D. γ carboxylic

63
Q

63.Which is a CORRECT statement of aromatic amino acids?
A. All are strongly hydrophilic
B. Histidine’s ring structure results in its being categorized as aromatic or basic, dependingon pH
C. On a molar basis, tryptophan absorbs more ultraviolet light than tyrosine.
D. The major contribution to the characteristic absorption of light at 280 nm by proteins is the phenylalanine R group.

A

C. On a molar basis, tryptophan absorbs more ultraviolet light than tyrosine.

64
Q

64.Which is TRUE of cystine?
A. Cystine forms when the —CH2—SH R group is oxidized to form a —CH2—S—S—CH2— disulfide bridge between two cysteines.
B. Cystine is an example of a nonstandard amino acid, derived by linking two standardamino acids.
C. Cystine is formed by the oxidation of the carboxylic acid group on cysteine.
D. Cystine is formed through a peptide linkage between two cysteines.

A

A. Cystine forms when the —CH2—SH R group is oxidized to form a —CH2—S—S—CH2— disulfide bridge between two cysteines.

65
Q

65.Why are amino acids considered as ampholytes?
A. may behave as an acid or a base depending on the pH of the milieu
B. exist as neutral molecule or an ion.
C. may be polar or a nonpolar molecule.
D. they are either standard or a nonstandard monomer in proteins.

A

A. may behave as an acid or a base depending on the pH of the milieu

66
Q

66.Titration of valine by a strong base, for example NaOH, reveals two pK ’s. Which reaction is seen at pK 2(pK 2= 9.62)?
A. —COOH + OH− → —COO− + H2O
B. —COOH + —NH2 → —COO− + —NH2+
C. —COO− + —NH2+ → —COOH + —NH2
D. —NH3+ + OH− → —NH2 + H2O

A

B. —COOH + —NH2 → —COO− + —NH2+

67
Q

67.Which is the predominant ionic form of glycine in a highly basic solution, pH = 13?
A. NH2 —CH2 —COOH
B. NH2 —CH2 —COO−
C. NH2 —CH3+ —COO−
D. NH3+ —CH2 —COOH

A

C. NH2 —CH3+ —COO−

68
Q

68.Which is the pI value of any amino acid having two functions groups, one alpha amino group and one carboxylic group?
A. is neutral near pH 4
B. computed as the sum of the two pKas of the two functional groups
C. zero at physiologic pH
D. equal to the value of either the functional groups

A

C. zero at physiologic pH

69
Q

69.What is the charge of amino acids with neutral R groups, at any pH below the pI?
A. a net negative
B. a net positive
C. no charged groups.
D. no net charge.

A

B. a net positive

70
Q

70.Which is reaction is involved in the formation of a peptide bond between two amino acids?
A. cleavage associated with removal of water
B. condensation associated with removal of water
C. group transfer
D. isomerization

A

B. condensation associated with removal of water

71
Q

71.How many peptide bonds does an oligopeptide made up of five amino acids have?
A. a disulfide bridge.
B. five peptide bonds.
C. four peptide bonds.
D. no free carboxyl group.

A

C. four peptide bonds.

72
Q

72.Which functional groups of an octapeptide composed of four repeating glycylalanyl units has charge?
A. one free amino group on an alanyl residue.
B. one free amino group on an alanyl residue and one free carboxyl group on a glycyl residue.
C. free amino group on a glycyl residue and free carboxyl group on an alanyl residue.
D. two free amino and two free carboxyl groups.

A

C. free amino group on a glycyl residue and free carboxyl group on an alanyl residue.

73
Q

73.What is the ionic specie of a tetrapeptide at the isoelectric pH?
A. only the amino and carboxyl termini contribute charge.
B. the amino and carboxyl termini are not charged.
C. it’s in its zwitterionic form.
D. there are four ionic charges.

A

C. it’s in its zwitterionic form.

74
Q

74.Which of the following is correct with respect to the amino acid composition of proteins?
A. Larger proteins have a more uniform distribution of amino acids than smaller proteins.
B. Proteins contain at least one each of the 20 different standard amino acids.
C. Proteins’ function usually follows its structure
D. Proteins with the same molecular weight have the same amino acid composition.

A

C. Proteins’ function usually follows its structure

75
Q

75.Which of the following refers to regions of regularly repeating conformations of the peptide chain?
A. Primary structure
B. Secondary structure
C. Tertiary structure
D. Quaternary structure

A

B. Secondary structure

76
Q

76.Which bond stabilizes an anti parallel beta sheets of a protein molecule?
A. peptide bond
B. glycosidic bond
C. peptidyl bond
D. hydrogen bond

A

A. peptide bond

77
Q

77.Positive nitrogen balance is present in:
A. Pregnant women
B. Post-surgical patients
C. Children with protein energy malnutrition
D. All of the above

A

A. Pregnant women

78
Q

78.True of transamination reactions:
A. They are reversible reactions
B. It does not involve the amino acid lysine
C. Pyridoxal phosphate serves as a cofactor for transamination reactions
D. All of the above

A

D. All of the above

79
Q

79.Glutamate dehydrogenase catalyzes what type of reaction?
A. Reductive biosynthesis
B. Transketolation
C. Oxidative deamination
D. Methyl group transfer

A

C. Oxidative deamination

80
Q

80.Which amino acid is not part of the PEST sequence?
A. Tyrosine
B. Proline
C. Glutamine
D. Serine

A

A. Tyrosine

81
Q

81.The function of ubiquitin is:
A. To act as a cofactor in transamination reactions
B. To allosterically activate the synthesis of urea
C. To facilitate the degradation of intracellular proteins
D. To help stabilize peptide bonds between amino acids

A

C. To facilitate the degradation of intracellular proteins

82
Q

82.Which of the following is a correct a-keto acid:amino acid transamination pair?
A. Pyruvate : Alanine
B. Glutamate : Glutamine
C. Fumarate : Arginine
D. Asparagine : Aspartic acid

A

A. Pyruvate : Alanine

83
Q

83.In amino acid catabolism, the α amino nitrogen is:
A. used as a substrate for glycogenesis
B. used as a substrate for fatty acid synthesis
C. excreted in the form of uric acid in humans
D. converted to a less toxic substance in the liver

A

D. converted to a less toxic substance in the liver

84
Q

84.Amino acid oxidases remove nitrogen from amino acids in the form of:
A. Urea
B. Ammonia
C. Uric acid
D. Glutamate

A

B. Ammonia

85
Q

85.Liver glutamate dehydrogenase activity is allosterically inhibited by all of the following EXCEPT:
A. ADP
B. ATP
C. NADH
D. GTP

A

A. ADP

86
Q

86.Which amino acid is capable of removing ammonia from the circulation?
A. Glycine
B. Arginine
C. Glutamate
D. Aspartate

A

C. Glutamate

87
Q

87.All of the following substances contribute to the synthesis of carbamoyl phosphate EXCEPT:
A. Ammonium ion
B. Carbon Dioxide
C. Ornithine
D. ATP

A

C. Ornithine

88
Q

88.A defect in the enzyme carbamoyl phosphate synthase I results in:
A. Ammonia intoxication
B. Increased urinary excretion of urea
C. Citrullinemia
D. All of the above

A

A. Ammonia intoxication

89
Q

89.This substance increases the affinity of the rate-limiting enzyme in urea biosynthesis for ATP:
A. Magnesium
B. N-acetylglutamate
C. Ammonia
D. Carbamoyl phosphate

A

B. N-acetylglutamate

90
Q

90.Fumarate from the cleavage of argininosuccinate re-forms this amino acid:
A. Arginine
B. Glutamate
C. Aspartate
D. Citrulline

A

C. Aspartate

91
Q

91.How many nitrogen atoms does urea have?
A. One
B. Two
C. Three
D. Four

A

B. Two

92
Q

92.Arginine produces ornithine by:
A. Condensation of arginine with urea
B. Hydrolytic cleavage of arginine
C. Cleavage through the action of argininosuccinase
D. ATP-mediated hydrolysis

A

B. Hydrolytic cleavage of arginine

93
Q

93.How many moles of ATP are needed for the urea cycle to occur?
A. One
B. Two
C. Three
D. Four

A

C. Three

94
Q

94.Toxic effects are more apparent when this enzyme is impaired in the urea cycle:
A. Ornithine transcarbamoylase
B. Arginase
C. Argininosuccinase
D. Argininosuccinic acid synthase

A

A. Ornithine transcarbamoylase

95
Q

95.Which of the following enzymes will cleave peptide bonds at the carboxyl terminal end of a basic amino acid?
A. Chymotrypsin
B. Carboxypeptidase A
C. Elastase
D. Chymotrypsin

A

D. Chymotrypsin

96
Q

96.What is the metabolic fate of the carbon skeleton of amino acids upon degradation?
A. Used for ATP synthesis
B. Used for fatty acid synthesis
C. Used for glucose synthesis
D. All of the above
E. None of the above – it is converted to urea

A

D. All of the above

97
Q

97.Fumarate is cleaved off:
A. Carbamoyl Phosphate Synthase I
B. Ornithine Transcarbamoylase
C. Argininosuccinate synthase
D. Argininosuccinase

A

D. Argininosuccinase

98
Q

98.Condensation with carbamoyl phosphate in the mitochondria:
A. Carbamoyl Phosphate Synthase I
B. Ornithine Transcarbamoylase
C. Argininosuccinate synthase
D. Argininosuccinase

A

B. Ornithine Transcarbamoylase

99
Q

99.N-acetylglutamate is a cofactor:
A. Carbamoyl Phosphate Synthase I
B. Ornithine Transcarbamoylase
C. Argininosuccinate synthase
D. Argininosuccinase

A

A. Carbamoyl Phosphate Synthase I

100
Q

100.ATP is hydrolyzed to AMP:
A. Carbamoyl Phosphate Synthase I
B. Ornithine Transcarbamoylase
C. Argininosuccinate synthase
D. Argininosuccinase

A

C. Argininosuccinate synthase

Biochemisty Main (29 decks)

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