Why is it necessary for glucose to be pumped into the cell r

Why is it necessary for glucose to be pumped into the cell rather than diffusing in? Glucose may have to be moved against a concentration gradient Glucose is too big for a facilitated diffusion protein channel. Glucose cannot pass through a phospholipid bilayer by simple diffusion. Glucose is repelled by the polar heads of the membrane phospholipid molecules.

Solution

The cell membrane is composed of two phospholipid bilayer where each molecule has single hydrophobic head and two hydrophilic tails. Hydrophobic heads are aligned along the inner side and outer side and the hydrophilic tail are in between the space. Thus, only small, nonpolar molecules can pass through the membrane by simple diffusion and rejects polar or partially charged, molecules such as glucose. Thus glucose is transferred through facilitated diffusion and another molecule through active transport.

Answer will be glucose cannot pass through a phospholipid bilayer by simple diffusion.