AP BIOLOGY

Detailed explanation-1: -(A) cAMP is the archetypical second messenger. Its levels increase rapidly following receptor-mediated activation of adenylyl cyclase (AC), which catalyzes the conversion of adenosine monophosphate (AMP) to cAMP.

Detailed explanation-2: -Calcium. The calcium ion (Ca2+) is perhaps the most common intracellular messenger in neurons. Indeed, few neuronal functions are immune to the influence-direct or indirect-of Ca2+.

Detailed explanation-3: -Each second messenger is associated with a particular type of protein kinase. For example, cAMP activates cAMP-dependent protein kinase (also called protein kinase A; PKA), whereas cGMP similarly functions via cGMP-dependent kinase.

Detailed explanation-4: -Adenosine 3′, 5′-cyclic monophosphate (cAMP) is a nucleotide that acts as a key second messenger in numerous signal transduction pathways. cAMP regulates various cellular functions, including cell growth and differentiation, gene transcription and protein expression.

Detailed explanation-5: -Second messengers are intracellular signaling molecules. Epinephrine is a hormone that is released into the bloodstream and is thus never inside the cell. cAMP, Ca2+ and IP3 are all examples of second messengers.