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Essential Biochemistry - Enzymes (Section 3)

1
What is the function of coenzymes?
Answer
(B)
They are organic cofactors.
2
Which of the following inhibits aldehyde dehydrogenase?
Answer
(A)
Disulfiram
3
Which of the following statements is true regarding allosteric enzymes?
Answer
(C)
Their activity is often regulated by modulators.
4
Which type of enzyme specificity is demonstrated when an enzyme catalyzes a reaction involving a single substrate?
Answer
(A)
Absolute specificity
5
Which type of inhibitor decreases both Vmax and Km?
Answer
(C)
Uncompetitive inhibition
6
What effect does a competitive inhibitor have on Km and Vmax?
Answer
(C)
Km increases, Vmax stays the same
7
What type of enzyme is involved in the joining of two molecules using energy from ATP?
Answer
(B)
Ligase
8
Which of the following statements are correct regarding enzyme inhibitors?
Answer
B
C
D
9
What is the role of the enzyme aspartate transaminase (AST) in clinical diagnostics?
Answer
(B)
Evaluation of liver disease and myocardial infarction
10
What effect does an irreversible inhibitor have on an enzyme?
Answer
(B)
It permanently inactivates the enzyme.
11
What type of enzyme inhibition involves the inhibitor binding to a site other than the active site?
Answer
(B)
Noncompetitive inhibition
12
Which of the following can be considered as an example of feedback inhibition?
Answer
(A)
The product of a metabolic pathway inhibits an enzyme that acts early in the pathway.
13
Which enzyme is commonly used in the diagnosis of acute pancreatitis?
Answer
(A)
Amylase
14
Which of the following statements is true regarding competitive inhibitors?
Answer
(C)
They increase the Km of the reaction.
15
What is the effect of increasing the concentration of an enzyme on the reaction rate?
Answer
(A)
The rate increases linearly.
16
Which of the following is an example of substrate specificity?
Answer
(B)
An enzyme can only bind to and catalyze one specific molecule or a set of closely related molecules.
17
What is the primary use of disulfiram?
Answer
(A)
Treatment of alcohol addiction
18
Which class of enzyme is primarily involved in oxidation-reduction reactions?
Answer
(A)
Oxidoreductases
19
Enzymes increase reaction rate by:
Answer
(A)
Selectively enhancing the rate of the forward reaction
20
What effect does a noncompetitive inhibitor have on the Km value?
Answer
(C)
Km remains unchanged.
21
Which of the following statements is true about the effect of an enzyme on a reaction?
Answer
(C)
It increases the rate of both the forward and reverse reactions.
22
Which enzyme is primarily responsible for digesting fats in the small intestine?
Answer
(B)
Lipase
23
What will be the effect of a decrease in temperature on enzyme activity?
Answer
(B)
Decrease the enzyme activity.
24
The alkaline phosphatases belong to:
Answer
(C)
Hydrolases
25
Which type of inhibitor binds at a site other than the active site?
Answer
(B)
Noncompetitive inhibitors
26
Which type of enzyme reaction involves the cleavage of bonds with the addition of water?
Answer
(C)
Hydrolases
27
Which of the following statements best describes allosteric regulation?
Answer
(B)
The enzyme is activated or inhibited by a molecule binding at a site other than the active site.
28
What is meant by enzyme saturation?
Answer
(A)
All the active sites are occupied by substrates.
29
What is a zymogen?
Answer
(B)
An inactive precursor of an enzyme.
30
Which of the following cofactors is NOT a metal ion?
Answer
(D)
Biotin
31
What is a key characteristic of isoenzymes?
Answer
(B)
They catalyze the same reaction but differ in structure.
32
Enzyme activity is most affected by which of the following factors?
Answer
(B)
Temperature
33
Which type of specificity involves an enzyme only reacting with one type of substrate?
Answer
(A)
Absolute specificity
34
Which type of inhibitor binds to the enzyme-substrate complex?
Answer
(C)
Uncompetitive
35
The 'induced fit' model explains that the enzyme and substrate:
Answer
(B)
Are flexible and change shape upon binding.
36
What is the relationship between Km and substrate affinity?
Answer
(B)
Km is inversely proportional to substrate affinity.
37
Which of the following is an example of a group-specific irreversible inhibitor?
Answer
(B)
DDT
38
Which of the following are the correct features of competitive inhibition?
Answer
A
B
D
39
What happens to the Km value in the presence of a competitive inhibitor?
Answer
(B)
It increases.
40
Which of the following enzymes is produced exclusively by the prostate gland?
Answer
(A)
Acid phosphatase
41
Which of the following is a suicide inhibitor or mechanism-based inactivator?
Answer
(C)
Penicillin
42
What type of inhibitor changes both Km and Vmax?
Answer
(C)
Uncompetitive inhibitor
43
Which of the following is a common feature of all enzymes?
Answer
(A)
They are all proteins.
44
Isoenzymes can be characterized as:
Answer
(D)
Multiple forms of given enzyme that catalyze same type of reactions
45
Which of the following is an example of a competitive inhibitor?
Answer
(C)
Ethanol
46
What type of molecule can act as a coenzyme?
Answer
(B)
A vitamin
47
Which of the following is an example of an allosteric enzyme?
Answer
(B)
Hemoglobin
48
Which class of enzyme is responsible for catalyzing the transfer of a phosphate group?
Answer
(C)
Kinases
49
A noncompetitive inhibitor:
Answer
(B)
Binds to a site other than the active site.
50
All of the following serum enzymes are elevated in myocardial infarction, except:
Answer
(A)
Alkaline phosphatase