Final Exam - Quizzes

Question 1

G proteins act on
a. tyrosine kinases
b. adenylate cyclase
c. insulin receptors
d. steroid hormones

Answer 1

b. adenylate cyclase

Question 2

Insulin binds to a receptor that _______.
I. is coupled to a G protein
II. possesses tyrosine kinsase activity
III. possesses serine/threonine phosphatase activity
IV. phosphorylates tyrosine residues of protein targets

a. I only
b. II only
c. I, III
d. II, IV

Answer 2

d. II, IV

Question 3

the activity of protein kinase A is affected by which of the following?
I. activated adenylate cyclase
II. levels of cAMP
III. phosphodiesterase

a. I only
b. II only
c. III only
d. I and II
e. I, II, and III

Answer 3

e. I, II, and III

Question 4

Which of the following is TRUE regarding receptor tyrosine kinases?

a. the insulin receptor has two insulin binding sites, one on each subunit
b. ligand binding to the receptor triggers autophosphorylation
c. following ligand binding and dimerization the receptor moves to the nucleus
d. A and B

Answer 4

d. A and B

Question 5

which of the following would PROLONG a hormone signal mediated via the G protein signal transduction system?

a. addition of a substance that activates protein phosphatases
b. addition of a substance that inhibits phosphodiesterases
c. addition of a substance that inhibits adenylate cyclase
d. B and C

Answer 5

b. addition of a substance that inhibits phosphodiesterases