AP BIOLOGY

Detailed explanation-1: -Paracrine signaling: a cell targets a nearby cell (one not attached by gap junctions). The image shows a signaling molecule produced by one cell diffusing a short distance to a neighboring cell. Autocrine signaling: a cell targets itself, releasing a signal that can bind to receptors on its own surface.

Detailed explanation-2: -Paracrine signaling acts on nearby cells, endocrine signaling uses the circulatory system to transport ligands, and autocrine signaling acts on the signaling cell. Signaling via gap junctions involves signaling molecules moving directly between adjacent cells.

Detailed explanation-3: -Paracrine Signaling Signals that act locally between cells that are close together are called paracrine signals. Paracrine signals move by diffusion through the extracellular matrix. These types of signals usually elicit quick responses that last only a short amount of time.

Detailed explanation-4: -Another major class of signaling enzymes is guanine-nucleotide-binding proteins, also called G proteins, a large family of signaling proteins that control a wide array of cellular functions, including motility, hormone responses, sensory perception, and neurotransmission.

Detailed explanation-5: -In paracrine signaling, a molecule released by one cell acts on neighboring target cells. An example is provided by the action of neurotransmitters in carrying signals between nerve cells at a synapse.