AP BIOLOGY

Detailed explanation-1: -GLUT4 is an insulin-responsive glucose transporter that is found in the heart, skeletal muscle, adipose tissue, and brain. It is present in the cytoplasm of cells in vesicles from which it is translocated to the plasma membrane under the influence of insulin.

Detailed explanation-2: -When glucose in the blood binds to glucose receptors on the beta cell membrane, a signal cascade is initiated inside the cell that results in insulin stored in vesicles in these cells being released into the blood stream. Increased insulin levels cause the uptake of glucose into the cells.

Detailed explanation-3: -It transports glucose into brain cells at a rate that is independent of the plasma level of glucose when it exceeds the physiological range of 4–10 mM. GLUT4 functions for the insulin-dependent translocation of glucose.

Detailed explanation-4: -The reduction of glucose in the blood results from the action of insulin. Glucose enters the beta cells of the pancreas through the glucose transporter GLUT2 and this is a major signal leading to the release of insulin from these cells that reaches the bloodstream.

Detailed explanation-5: -Facilitative glucose transporters (GLUTs) These are responsible for the bidirectional transport of glucose in tissues and cells. This involvesusing facilitative diffusion to carry glucose down a concentration gradient, into the cell.