Plasma Membranes

Lipid Bilayer: This is a universal component of all cell membranes. The lipid bilayer acts as a sturdy barrier that prevents random substances from entering or leaving the cell.

Semi-permeable Membrane: This is a type of biological or synthetic membrane that will allow certain molecules or ions to pass through it by diffusion and occasionally specialized 'transport proteins'.

Cell Wall: This is an additional layer present outside the plasma membrane in plant cells, fungi, bacteria, etc., providing these cells with structural support and protection.