Oxford University Press | Online Resource Centre

Choose your answer by clicking the radio button next to your choice and then press 'Submit' to get your score.

Question 1

Which of the following reactions is catalyzed by the enzyme adenylate cyclase?

a) The conversion of ATP to cyclic AMP.

b) The conversion of cyclic AMP to AMP.

c) The conversion of cyclic AMP to ATP.

d) The conversion of AMP to cyclic AMP.

Question 2

What is the product, indicated by the letter C in the following diagram?

a) inositol triphosphate

b) diacylglycerol

c) inositol diphosphate

d) phosphatidylinositol diphosphate

Question 3

Which of the following statements is true for diacylglycerol (DG) formed in the following reaction?

a) It is a hydrophobic molecule.

b) It moves into the cytoplasm.

c) It deactivates an enzyme called protein kinase C.

d) It is not a secondary messenger.

Question 4

Which of the following statements is true for inositol triphosphate (IP₃) formed in the reaction below?

a) It is a hydrophobic molecule.

b) It moves into the cytoplasm.

c) It deactivates the release of calcium ions.

d) It is not a secondary messenger.

Question 5

Which of the following statements is untrue about G-proteins?

a) G-proteins consist of four protein subunits.

b) G-Proteins act as signal proteins.

c) G-Proteins interact with receptors.

d) G-Proteins bind GDP in the resting state.

Question 6

Which of the following is true when a G-protein interacts with a receptor?

a) The G-protein is split into a γ-subunit and an α, β-dimer

b) The G-protein is split into a β-subunit and an α, γ-dimer

c) The G-protein is split into an α-subunit and a β, γ-dimer

d) The G-protein is split into its component protein subunits

Question 7

Which of the following subunits activates adenylate cyclase?

a) The α_i-subunit

b) The α_s-subunit

c) The α_q-subunit

d) The α_o-subunit

Question 8

Which of the following is untrue with respect to small G-proteins?

a) Small G-proteins consist of a single protein.

b) Ras is an example of a small G-protein.

c) Small G-proteins bind GDP in the resting state.

d) Small G-proteins are the same as G-proteins, but have a lower molecular weight.

Question 9

Which of the following statements best explains the action of lithium salts in treating manic depressive illness?

a) They inhibit adenylate cyclase.

b) They inhibit phospholipase C.

c) They inhibit protein kinase C.

d) They inhibit a phosphatase enzyme.

Question 10

Which of the following statements is true about calmodulin

a) It is a protein which binds calcium ions and activates protein kinases.

b) It is a protein which binds calcium ions and binds to DNA to activate transcription.

c) It is a protein which transports calcium ions across the cell membrane.

d) It is a protein which modifies calcium ion concentration within the cell.

Oxford University Press, Online Resource Centre, Chapter 05.

Chapter 05

Instructions