Biochemistry - Problem Drill 11: Enzymes - Basic Concepts
Question No. 1 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
1. With respect to enzymes select the best statement below.
Question
(A) Enzymes are proteins (usually).
(B) Enzymes accelerate the rate of a chemical reaction.
(C) Enzymes require metal atoms as a cofactor.
(D) Cofactors are required by enzymes to function.
(E) All of the above
A. Incorrect!
No, while this answer is correct it is not the best selection.
B. Incorrect!
No, while this answer is correct it is not the best selection.
C. Incorrect!
No, while this answer is correct it is not the best selection.
Feedback
D. Incorrect!
No, while this answer is correct it is not the best selection.
E. Correct!
Yes, this is the best response to the question.
All of these statements are correct however E is the best answer.
The correct answer is (E).
Solution
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Question No. 2 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
2. With respect to the structure below, the region indicated with the arrow is:
Question
(A) Amine bond
(B) Peptide bond
(C) Carboxyl bond
(D) Dehydration bond
(E) None of the above
A. Incorrect!
No, this answer is incorrect.
B. Correct
Yes, the arrow is pointing to a peptide bond.
C. Incorrect!
No, this answer is incorrect.
Feedback
D. Incorrect!
No, this answer is incorrect.
E. Incorrect!
No, this answer is incorrect.
The structure indicated by the letter arrow is a peptide bond.
The correct answer is (B).
Solution
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Question No. 3 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
3. The _______ area of the enzyme binds the substrate.
Question
(A) Business end.
(B) Catalytic reaction.
(C) Binding site.
(D) Active site.
(E) None of the above
A. Incorrect!
No, this is not the best answer to the question.
B. Incorrect!
No, this is not the best answer to the question.
C. Incorrect!
No, this is not the best answer to the question.
Feedback
D. Correct!
Yes, this is the best answer for the question. While sometimes the active site may
be referred to as the binding site or catalytic reaction site the most accurate answer
is “active site”.
E. Incorrect!
No, this is not the best answer to the question there is a correct answer.
The region of an enzyme that binds the substrate and then carries out the catalytic
reaction is called the active site.
The correct answer is (D).
Solution
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Question No. 4 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
4. There is a sequence of orderly steps in enzyme catalyzed reactions. Please
arrange the following statements in the correct order.
1.
2.
3.
4.
5.
Question
Enzyme substrate complex reaches the transition state.
Formation of enzyme substrate complex.
Release of product.
Formation of enzyme product complex.
Substrate approaches the active site.
(A) 5,
(B) 5,
(C) 5,
(D) 5,
(E) 5,
1,
2,
4,
1,
2,
3,
1,
3,
2,
4,
4,
4,
1,
4,
1,
2
3
2
3
3
A. Incorrect!
No, this is not the correct sequence of reactions for enzyme catalysis.
B. Correct!
Yes this is the correct sequence of reaction for enzyme catalysis.
C. Incorrect!
No, this is not the best answer to the question.
Feedback
D. Incorrect!
No, this is not the best answer to the question.
E. Incorrect!
No, this is not the best answer to the question.
The correct sequence for enzyme catalysis is:
Substrate approaches the active site.
Formation of enzyme substrate complex.
Enzyme substrate complex reaches the transition state.
Formation of enzyme product complex.
Release of product.
The correct answer is (B).
Solution
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Question No. 5 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
5. Which of the following statements is incorrect with respect to the “Lock and
Key” hypothesis of enzymes?
Question
(A) The enzyme is considered equivalent to the lock.
(B) The substrate is considered equivalent to the key.
(C) The lock and key are specific for each other.
(D) This theory accounts for transition state stabilization.
(E) This hypothesis was postulated in 1890.
A. Incorrect!
No. This is a correct statement so an incorrect response.
B. Incorrect!
No. This is a correct statement so an incorrect response.
C. Incorrect!
No. This is a correct statement so an incorrect response.
Feedback
D. Correct!
The lock and key hypothesis does not account for the transition state stabilization
that occurs with enzyme reaction.
E. Incorrect!
No. This is a correct statement so an incorrect response.
The lock and key hypothesis does not account for the transition state stabilization
that occurs with enzyme reaction.
The correct answer is (D).
Solution
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Question No. 6 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
6. With respect to the Induced Fit Hypothesis which of the following statements
are incorrect?
Question
(A) Enzymes are flexible.
(B) The active site of an enzyme is reshaped by substrate binding.
(C) Substrate binds to a rigid active site.
(D) Enzyme amino acids move when involved in binding substrate.
(E) The substrate can also change confirmation to fit.
A. Incorrect!
No. This is a correct statement so an incorrect response.
B. Incorrect!
No. This is a correct statement so an incorrect response.
C. Correct!
Yes, the binding site is not ridged and can change shape to accommodate binding
the substrate.
Feedback
D. Incorrect!
No. This is a correct statement so an incorrect response.
E. Incorrect!
No. This is a correct statement so an incorrect response.
Characteristics of the Induced Fit Hypothesis: Enzymes are flexible and the active
site is reshaped y substrate binding, transitions state formation, product and
product release.
The correct answer is (C).
Solution
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Question No. 7 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
7. Look at the graph below of reactants going to products with and without an
enzyme present. Does A, B, C, D or E represent the activation energy in the
presence of an enzyme?
Question
A.
B.
C.
D.
E.
A
B
C
D
E
A. Incorrect!
No, this part of the graph does not represent the activation energy of an enzyme
catalyzed reaction.
B. Incorrect!
No, this part of the graph does not represent the activation energy of an enzyme
catalyzed reaction.
C. Incorrect!
No, this part of the graph does not represent the activation energy of an enzyme
catalyzed reaction.
Feedback
D. Correct!
Yes, this segment does represent the reaction catalyzed by an enzyme.
E. Incorrect!
No, this part of the graph does not represent the activation energy of an enzyme
catalyzed reaction.
Look at the axis of the graph and you will see that the “Energy” axis is lowered.
This is indicative of an enzyme catalyzed reaction.
The correct answer is (D).
Solution
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Question No. 8 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
8. Look at the graph below of reactants going to products with and without an
enzyme present. Does A, B, C, D or E represent the transition state of a reactant
going to a product?
Question
(A) A
(B) B
(C) C
(D) D
(E) E
A. Correct!
Yes. While this answer is correct it is not the best selection.
B. Incorrect!
No. This is not the correct response.
C. Incorrect!
No. This is not the correct response.
Feedback
D. Incorrect!
No. This is not the correct response.
E. Incorrect!
No. This is not the correct response.
The arrow labeled “A” is the transition state of an uncatalyzed reaction going from
reactant to product. Both catalyzed and uncatalyzed reactions go through a
“transition state”.
The correct answer is (A).
Solution
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Question No. 9 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
9. Look at the graph below of reactants going to products with and without an
enzyme present. Does A, B, C, D or E represent the activation energy without
enzyme.
Question #09
(A) A
(B) B
(C) C
(D) D
(E) E
A. Incorrect!
No. This is not the correct response.
B. Incorrect!
No. This is not the correct response.
Feedback on
Each Answer
Choice
C. Incorrect!
No. This is not the correct response.
D. Incorrect!
No. This is not the correct response.
E. Correct!
Yes, “E” represents the activation energy without enzyme catalysis.
The area of the graph indicated by “E” indicated the activation energy without an
enzyme.
Solution
The correct answer is (E).
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Question No. 10 of 10
Instructions: (1) Read the problem and answer choices carefully (2) Work the problems on paper as
needed (3) Pick the answer (4) Go back to review the core concept tutorial as needed.
10. Which of the following statements is correct with respect to an enzyme
prosthetic group?
Question #10
(A) Prosthetic groups are protein molecules.
(B) Prosthetic groups are loosely bound.
(C) Prosthetic groups are not usually essential to the enzymes catalytic
function.
(D) Ca is an example of a prosthetic group in the heme part of
hemoglobin.
(E) Prosthetic groups are nonprotein organic molecules.
A. Incorrect!
No, this answer is not correct with respect to an enzyme prosthetic group.
B. Incorrect!
No, this answer is not correct with respect to an enzyme prosthetic group.
Feedback on
Each Answer
Choice
C. Incorrect!
No, this answer is not correct with respect to an enzyme prosthetic group.
D. Incorrect!
No, this answer is not correct with respect to an enzyme prosthetic group.
E. Correct
Yes, this statement is correct.
Enzyme prosthetic group characteristics include:
1. Prosthetic groups are nonprotein organic molecule.
2. Tightly bound.
3. Essential to the enzymes catalytic function.
4. Example of a prosthetic group is the heme part of hemoglobin.
The correct answer is (E).
Solution
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