Medical Biology_Mock Test #4

The process of stabilizing the structure of an enzyme in its active form by the binding of a molecule outside the active site is an example of __________.

• allosteric activation
• noncompetitive inhibition
• Cooperativity
• competitive inhibition
• feedback inhibition

Which of the following statements about allosteric proteins is/are true?

• They exist in active and inactive conformations.
• They are sensitive to environmental conditions.
• They are acted on by inhibitors.
• All of the first three listed responses are correct.
• None of the first three listed responses is correct.

The binding of an allosteric inhibitor to an enzyme causes the rate of product formation by the enzyme to decrease. Which of the following best explains why this decrease occurs?

• The allosteric inhibitor binds to the substrate and prevents it from binding at the active site.
• The allosteric inhibitor binds to the active site, preventing the substrate from binding.
• The allosteric inhibitor causes free energy change of the reaction to increase.
• The allosteric inhibitor causes a structural change in the enzyme that prevents the substrate from binding at the active site.
• The allosteric inhibitor lowers the temperature of the active site.

What enzyme joins Okazaki fragments?

• Helicase
• DNA polymerase
• Primase
• DNA ligase
• Topoisomerase

At each end of a DNA replication bubble is __________.

• a telomere
• an origin of replication
• a ribosome
• a replication fork
• a gene

After the formation of a replication bubble, which of the following is the correct sequence of enzymes used for the synthesis of the lagging DNA strand?

• Primase, helicase, DNA polymerase, ligase
• Helicase, primase, ligase, DNA polymerase
• Helicase, DNA polymerase, primase, ligase
• Ligase, primase, DNA polymerase, helicase
• Helicase, primase, DNA polymerase, ligase

Where do the reactions of the citric acid cycle occur in eukaryotic cells?

• The intermembrane space of the mitochondrion
• Across the inner membrane of the mitochondrion
• The matrix of the mitochondrion
• The cytosol
• The cristae of the mitochondrion

How many molecules of ATP are gained by substrate-level phosphorylation from the complete breakdown of a single molecule of glucose in the presence of oxygen?

• 4.0
• About 16 ATP
• 3.0
• 2.0
• About 32 ATP

Which of the following represents the major energy-related accomplishment of the citric acid cycle, even though it is not the only energy-related accomplishment?

• Formation of CO2
• Completion of substrate-level phosphorylation
• Formation of NADH and FADH2
• Utilization of O2
• Formation of ATP

The starting point of the Kreb's Cycle

• Acetyl CoA and Citrate
• Oxaloacetate and Acetyl CoA
• Acetyl CoA and Isocitrate
• Acetyl CoA and CO2
• Not correct response