Tissues that utilize the glucose transporter GLUT1 while tis

Tissues that utilize the glucose transporter GLUT1______; while tissues that utilize GLUT2_________

A. benefit from its high Km to obtain glucose under normal conditions; benefit from its low Km to only obtain glucose at low levels.

B. benefit from its high Km to only carry out glycolysis when there is an over abundance of glucose in the blood; include tissues that not only utilize glucose, but are responsive to glucose levels in the blood for hormone production

C. benefit from its low Km to obtain glucose from the blood under most normal conditions; only obtain glucose when it is at higher plasma concentrations when it is appropriate to release glucagon

D. benefit from its low Km to obtain glucose from the blood under most normal conditions; only obtain glucose when it is at higher plasma concentrations for example when it is appropriate to release insulin

Solution

Answer is D.

GLUT 1 or Glucose Transporter 1 is located in the plasma membrane of cells throughout the body, as they are responsible for maintaining a basal/minimum rate of glucose uptake. The Km value in this case is lower , therefore, GLUT1 has higher affinity for glucose.

GLUT 2 has a high Km value and has low affinity for glucose and is located in the plasma membrane of hepatocytes and pancreatic beta cells. The high Km of GLUT 2 allows for glucose sensing; rate of glucose entry is proportional to glucose levels, hence the need for release of insulin.