A cell expresses a transmembrane protein that is cleaved at the plasma membrane to release an extracellular fragment. The fragment binds to receptor proteins on nearby cells and activates signaling pathways resulting in altered gene expression in the cells. Which of the following best describes this form of intercellular signaling?

(A)Contact-dependent signaling
(B)Paracrine signaling
(C)Endocrine signaling
(D)Autocrine signaling

(B) Paracrine signaling

Explanation: Paracrine signaling occurs between cells that are relatively within a short distance apart. The signaling triggers quick responses and can last only for a short period of time because of the wearing-off of the paracrine ligands (neurotransmitters).

Cells that exhibit paracrine factors release them into the immediate extracellular environment.

the three components of a nucleotide are the nitrogenous base, the phosphate group and the five-carbon sugar.