UNE BIOCHEM UNIT 1 UPDATED
Questions with CORRECT Answers
How do most enzymes reduce the activation energy needed to move a reaction forward?
Providing an active site most complementary to the transition state; Providing an environment
free of water; Providing energy to the reaction by the cleavage of ATP; Providing an active site
complementary to the substrate - CORRECT ANSWER - Providing an active site most
complementary to the transition state
Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of the
following classes of enzymes? Transferases; Ligases; Lyases; Hydrolases - CORRECT
ANSWER - Hydrolases
Cleavage of fructose 1,6-bisphosphate to dihydroxyacetone and glyceraldehyde 3-phosphate is
achieved by what class of enzymes? Lyase; Transferase; Hydrolase; Ligase - CORRECT
ANSWER - Lyase
Which of the following cofactors or coenzymes would not typically participate in an activation
transfer reaction? Pyridoxal phosphate (PLP); Thiamine pyrophosphate; Biotin; Coenzyme A;
NADH - CORRECT ANSWER - NADH
Changes in the physiological variables listed below can alter the affinity of hemoglobin for
oxygen. Which of the following will increase the affinity of hemoglobin for oxygen? Increase in
temperature; Increase in CO2; Increase in 2,3-bisphosphoglycerate (BPG); Increase in pH -
CORRECT ANSWER - Increase in pH
Changes in the physiological variables listed below can alter the affinity of hemoglobin for
oxygen. Which of the following will lower the affinity of hemoglobin for oxygen? Decrease in
protons; Increase in 2,3-bisphosphoglycerate (BPG); Decrease in carbon dioxide; Increase in pH
- CORRECT ANSWER - Increase in 2,3-bisphosphoglycerate (BPG)
Which of the following best describes the structure of heme? A planar porphyrin ring that binds
iron; A nicotinamide structure that is readily oxidized; A negatively charged phosphate group; An
N-link glycosylation - CORRECT ANSWER - A planar porphyrin ring that binds iron
, Movement of ammonia from an amino acid to an α-keto acid involves a family of enzymes best
categorized as which of the following? Isomerases; Ligases; Transferases; Lyases - CORRECT
ANSWER - Transferases
Methylation is typical on __________ nucleotides. G; A; T; U - CORRECT ANSWER -G
An unknown compound is added to a reaction. Overall, the Vmax of the reaction is decreased but
the Km of the enzyme involved is unchanged. This compound is best defined as which of the
following? Substrate; Competitive Inhibitor; Cofactor; Noncompetitive Inhibitor - CORRECT
ANSWER - Noncompetitive Inhibitor
In the image below the blue line indicates enzyme kinetics with no inhibitor present. Based on
this information which of the following is true? More info is needed; The green line shows
enzyme kinetics with the addition of a noncompetitive inhibitor; The red line shows enzyme
kinetics with the addition of a noncompetitive inhibitor; The green line shows enzyme kinetics
with the addition of a competitive inhibitor - CORRECT ANSWER - The green line shows
enzyme kinetics with the addition of a noncompetitive inhibitor
If a mutation is made within the active site of an enzyme resulting in an increase in Km, which of
the following will be true with respect to the enzyme kinetics? The concentration of a substrate
needed to reach 1/2 Vmax will not change; The enzyme will require a higher substrate
concentration to reach 1/2 Vmax; The enzyme will require a higher substrate concentration to
reach 1/2 Vmax; the Vmax of the reaction will increase. - CORRECT ANSWER - The
enzyme will require a higher substrate concentration to reach 1/2 Vmax
Which of the following can NOT be found on the Michaelis-Menten graph? 1/Vmax; vi; Km;
Vmax/2 - CORRECT ANSWER - 1/Vmax
The following represents a series of reactions. As levels of S2 increase, this will increase the
production of C. Which of the following best describes this type of regulation in a biosynthetic
pathway? Covalent regulation; Inducible regulation; Feedback inhibition; Feedforward activation
- CORRECT ANSWER - Feedforward activation
Questions with CORRECT Answers
How do most enzymes reduce the activation energy needed to move a reaction forward?
Providing an active site most complementary to the transition state; Providing an environment
free of water; Providing energy to the reaction by the cleavage of ATP; Providing an active site
complementary to the substrate - CORRECT ANSWER - Providing an active site most
complementary to the transition state
Chymotrypsin is a protease that cleaves peptide bonds. It is characterized as which of the
following classes of enzymes? Transferases; Ligases; Lyases; Hydrolases - CORRECT
ANSWER - Hydrolases
Cleavage of fructose 1,6-bisphosphate to dihydroxyacetone and glyceraldehyde 3-phosphate is
achieved by what class of enzymes? Lyase; Transferase; Hydrolase; Ligase - CORRECT
ANSWER - Lyase
Which of the following cofactors or coenzymes would not typically participate in an activation
transfer reaction? Pyridoxal phosphate (PLP); Thiamine pyrophosphate; Biotin; Coenzyme A;
NADH - CORRECT ANSWER - NADH
Changes in the physiological variables listed below can alter the affinity of hemoglobin for
oxygen. Which of the following will increase the affinity of hemoglobin for oxygen? Increase in
temperature; Increase in CO2; Increase in 2,3-bisphosphoglycerate (BPG); Increase in pH -
CORRECT ANSWER - Increase in pH
Changes in the physiological variables listed below can alter the affinity of hemoglobin for
oxygen. Which of the following will lower the affinity of hemoglobin for oxygen? Decrease in
protons; Increase in 2,3-bisphosphoglycerate (BPG); Decrease in carbon dioxide; Increase in pH
- CORRECT ANSWER - Increase in 2,3-bisphosphoglycerate (BPG)
Which of the following best describes the structure of heme? A planar porphyrin ring that binds
iron; A nicotinamide structure that is readily oxidized; A negatively charged phosphate group; An
N-link glycosylation - CORRECT ANSWER - A planar porphyrin ring that binds iron
, Movement of ammonia from an amino acid to an α-keto acid involves a family of enzymes best
categorized as which of the following? Isomerases; Ligases; Transferases; Lyases - CORRECT
ANSWER - Transferases
Methylation is typical on __________ nucleotides. G; A; T; U - CORRECT ANSWER -G
An unknown compound is added to a reaction. Overall, the Vmax of the reaction is decreased but
the Km of the enzyme involved is unchanged. This compound is best defined as which of the
following? Substrate; Competitive Inhibitor; Cofactor; Noncompetitive Inhibitor - CORRECT
ANSWER - Noncompetitive Inhibitor
In the image below the blue line indicates enzyme kinetics with no inhibitor present. Based on
this information which of the following is true? More info is needed; The green line shows
enzyme kinetics with the addition of a noncompetitive inhibitor; The red line shows enzyme
kinetics with the addition of a noncompetitive inhibitor; The green line shows enzyme kinetics
with the addition of a competitive inhibitor - CORRECT ANSWER - The green line shows
enzyme kinetics with the addition of a noncompetitive inhibitor
If a mutation is made within the active site of an enzyme resulting in an increase in Km, which of
the following will be true with respect to the enzyme kinetics? The concentration of a substrate
needed to reach 1/2 Vmax will not change; The enzyme will require a higher substrate
concentration to reach 1/2 Vmax; The enzyme will require a higher substrate concentration to
reach 1/2 Vmax; the Vmax of the reaction will increase. - CORRECT ANSWER - The
enzyme will require a higher substrate concentration to reach 1/2 Vmax
Which of the following can NOT be found on the Michaelis-Menten graph? 1/Vmax; vi; Km;
Vmax/2 - CORRECT ANSWER - 1/Vmax
The following represents a series of reactions. As levels of S2 increase, this will increase the
production of C. Which of the following best describes this type of regulation in a biosynthetic
pathway? Covalent regulation; Inducible regulation; Feedback inhibition; Feedforward activation
- CORRECT ANSWER - Feedforward activation
