cAMP is a ______ messenger.

Prepare for the Foundations of Biology Exam 1. Dive into key biological concepts with multiple choice questions, hints, and explanations. Ace the exam with our efficient study methods!

cAMP functions as a secondary messenger: it is produced inside the cell after an extracellular signal binds to a receptor, and it relays and amplifies the message by activating downstream targets like protein kinase A. This intracellular mediator carries the signal from the receptor to intracellular pathways, leading to phosphorylation of proteins and changes in cellular activity. The primary messenger is the outside molecule itself (the hormone or neurotransmitter) that initiates the signal, not the inside relay. Lipid messengers are lipid-derived molecules such as DAG or IP3, whereas cAMP is a nucleotide, not a lipid. A receptor protein is the molecule that binds the signal at the membrane or inside the cell, not the internal messenger that transmits the signal.