In a certain signal transduction pathway, the binding of an extracellular molecule to a cell-surface protein results in a rapid increase in the concentration of cyclic AMP inside the cell. The cyclic AMP binds to and activates cytosolic enzymes that then activate other enzymes in the cell. Which of the following statements best describes the role of cyclic AMP in the signal transduction pathway?
a) It acts as a signaling molecule that passes the signal from the cell to other cells.
b) It acts as a receptor that carries the signal from outside the cell to inside the cell.
c) It acts as a second messenger that helps relay and amplify the signal within the cell.
d) It acts as a channel protein that transmits the signal across the cell’s nuclear membrane.

C. IT ACTS AS A SECOND MESSENGER THAT HELPS RELAY AND AMPLIFY THE SIGNALS WITHIN THE CELLS

Explanation:

cAMP works as a second messager for the transduction of signals from cells to another. In cells, many pathways of signal transduction involves second messenger which includes non-protein molecules that pass through a signal initiated by the binding of a ligand to its receptor. The Ligand is the first messenger. Other examples of second messenger aside from CAMP includes calcium ion, inositol phoshate.

Signal transduction by CAMP happens as Adenylyl cyclase converts ATP into cAMP by removing two phosphates from it. cAMP activates protein kinase A thereby allowing the target cells to be phosphorylated and then pass the signal. cAMP signaling is turned off by enzymes called phosphodiesterases, the cAMP ring is broken down into adenosine monophosphate which acts as a stop signal.

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.