1. What is the role of cAMP? a) cAMP directly phosphorylates different types of

Question

1. What is the role of cAMP?

a) cAMP directly phosphorylates different types of proteins in the cell

b) cAMP is a subunit of the G protein and activates adenylate cyclase

c) as its concentration increases, cAMP molecules activate protein kinases

d) as its concentration decrease, cAMP molecules activate protein kinases

2. what is the first step in termination actions of cAMP

a) the hormone diffuses across the cell membrane

b) the hormone unbinds from the receptor

c) protein kinase A degrades the membrane receptor

d) adenylate cyclase degrades cAMP

3. what stimulates the anterior pituitary to release a hormone

a) an electrical signal from the hypothalamus

b) a hormone secreted from the hypothalamus

c) hormones from the anterior pituitary are released spontaneously, nothing regulates their release

d) a hormone from the posterior pituitary

4. what action do thyroid hormones have on the anterior pituitary?

a) thyroid hormones inhibit the release of TSH

b) thyroid hormones stimulates the release of more TSH

c) thyroid hormones stimulates the release of TRH

d) thyroid hormones inhibits the release of GH

Explanation / Answer

1. (c) as Cytosolic cAMP increases, it activates PKA (Protein kinase A) by binding to the regulatory subunit of PKA

2.(b) as the hormone unbinds from the receptor,Gs alpha subunit slowly catalyzes the hydrolysis of GTP to GDP, deactivating the Gs protein, shutting off the cAMP pathway

3 (b) hormone secretion from anterior pituitary is regulated by hormones secreted by the hypothalamus.For example, ACTH(Adrenocorticotropic) is secreted by the anterior pituitary in response to corticotropin-releasing hormone from the hypothalamus

4. (a) blood concentrations of thyroid hormones increase above a certain threshold thyroid hormones inhibit the release of TSH from the anterior pituitary gland via feedback mechanism by inhibiting the secretion of TRH from the hypothalamus.

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