Question

The amplification of the signal from a water-soluble hormone is achieved through an increase in _______. a) cAMP in the cytoplasm b) phosphodiesterase in the cytoplasm plasma membrane receptors c) water-soluble hormone in the blood d) adenylate cyclase in the plasma membrane.

Answer 1

cAMP in the cytoplasm

Step-by-step explanation:

The water-soluble hormones diffuse through blood and bind to their receptors present at the exterior surface of their target cells. A water-soluble hormone cannot cross the non-polar core of the membrane. Binding of the hormone to its receptor at the cell surface activates the membrane protein called G protein.

The activated G protein triggers the synthesis of cAMP from ATP by activation of adenylyl cyclase. The catalytic site of adenylyl cyclase is present towards the inner surface of the plasma membrane and therefore cAMP is formed inside the cell. cAMP activates protein kinases which in turn phosphorylate one or more cellular proteins to bring about the desired physiological response.