diffusion , active transport

a.active transport requires conformational changes in the transport protein associated with the transport process and facilitated diffusion does not.

b.active transport requires an integral membrane protein to carry out the transport and facilitated diffusion does not.

c.facilitated diffusion requires a protein lined pore in the membrane and active transport does not.

d.facilitated diffusion depends on integral membrane proteins that establish an electrical or chemical energy gradient of the transported substance while active transport uses energy from ATP.

e.facilitated diffusion requires cellular energy (usually in the form of ATP) and active transport does not.

The transport process a cell uses depends on its specific needs. For example, red blood cells rely on facilitated diffusion to move glucose across membranes, whereas intestinal epithelial cells use active transport to take in glucose from the gut. Facilitated diffusion is effective for red blood cells because the concentration of glucose in the blood is stable and higher than the cellular concentration. On the other hand, active transport is needed in the gut because there are large fluctuations of glucose concentration as a result of eating.


2011-09-21 09:41:37 補充：
e.facilitated diffusion requires cellular energy (usually in the form of ATP) and active transport does not. 打錯咗
應該是：
active transport requires cellular energy (usually in the form of ATP) and facilitated diffusion does not.