Answer:
1. Phospholipid bilayer - The lipid bilayer acts as a barrier to the passage of molecules and ions into and out of the cell
2. Proteins - Membrane transport protein (or transporter) is a kind of membrane protein that involved in the movement of ions, small molecules, or macromolecules across a biological membrane.
3. Carbohydrates - Carbohydrates covalently linked to proteins (glycoproteins) or lipids (glycolipids) are also a part of cell membranes, and function as adhesion and address loci for cells.
4. Cholesterol - Cholesterol reduces permeability of lipid membranes. ... Cholesterol plays has a role in membrane fluidity but it's most important function is in reducing the permeability of the cell membrane.
Explanation:
