Question

The survival, proliferation, and size of each cell in an animal are controlled by extracellular signal molecules secreted by neighboring and distant cells. Many of these signal molecules bind to a cell-surface ___ and trigger various extracellular signaling pathways.

a. substrate
b. signal amplifier
c. signal integrator
d. receptor

Answer 1

Extracellular signal molecules bind to a cell-surface receptor to control the survival, proliferation, and size of each cell. These receptors initiate signaling pathways that result in various cellular responses. Abnormalities in these processes can lead to diseases like cancer.

Step-by-step explanation:

The survival, proliferation, and size of each cell in an animal are controlled by extracellular signal molecules secreted by neighboring and distant cells. Many of these signal molecules bind to a cell-surface receptor and trigger various extracellular signaling pathways.

In multicellular organisms, there are different categories of signaling such as paracrine signaling, endocrine signaling, autocrine signaling, and direct signaling across gap junctions. These signaling molecules, often referred to as ligands, bind to cell-surface receptors sparking a signaling cascade within the cell that can result in a variety of responses including protein synthesis, metabolic changes, cell growth, or programmed cell death (apoptosis). Errors in signaling and receptor function can have detrimental effects, often resulting in diseases such as cancer. Cell signaling pathways are intricate and essential for maintaining cellular function and communication.