Question

Name a membrane component that makes the membrane more permeable and one that reduces the permeability. Explain why each component affects the permeability it does.

Answer 1

• A membrane component that increases the permeability of the membrane is integral proteins that are embedded in the cell membrane. They are also known as membrane transporters.
• A membrane component that makes the membrane impermeable is phospholipid bilayer, by which the majority of the cell membrane is made of.

Proteins increase permeability by : They increase the permeability of the cell by facilitating the charged molecules or substances outside the cell into the cell through them ( which are embeded in the plasma membrane). They form a hydrophilic passage through the plasma membrane of the cell such that the hydrophylic molecules can pass through them from outside the cell to inside the cell.

Lipid bilayer decrease the permeability : This is mainly because of the hydrophobic nature of lipid bilayer. Most of the substances that has to be transported into the cell are hydrophylic. The hydrophylic substance gets repelled by the hydrophobic phospholipid, that constitute majority of the cell membrane.