Question

Channels in the plasma membrane through which molecules enter or leave the cell are ___ .

Answer 1

Channels in the plasma membrane through which molecules enter or leave the cell are membrane proteins. The phospholipid head and the tail make up the phospholipid bilayer. Small uncharged molecules can diffuse freely through a phospholipid bilayer. However, the bilayer is impermeable to larger polar molecules (such as glucose and amino acids) and to ions. The membrane proteins help in the transport of larger molecules.