to form channels to allow passage of non-polar solutes into the cell

to form channels to allow passage of fatty acids solutes into the cell

to form channels to allow passage of polar or charged solutes into the cell.

to form channels to allow passage of triglycerides into the cell

to form channels to allow passage of cholesterol into the cell

The lipid bilayer of biological membranes are formed by phospholipid molecules with hydrophilic fatty-acid, tailgroups and hydrophobic headgroups

Micelles are tiny droplets of phospholipids in water. In each micelle the headgroups of the phopholipids are exposed to the water and the tailgroups protected from the water in the centre of the micelle

The biological membrane is described as fluid because the phospholipid molecules but not the proteins can move around in the lipid bilayer

Integral proteins can be removed from biological membranes by mild chemical treatments that leave the lipid bilayer intact

Cell membranes contain only phospholipid and protein molecules

The cell membranes glycolipids

A mesh of fibrous proteins and the interstitial fluid that is made of complex carbohydrates

Collagen, elastin and fibronectin

Tight junctions, desmosomes and gap junctions

The extracellular matrix, cell adhesion molecules and specialized junctions

The lipid solubility, the permeability constant and the surface area

The surface area, the concentration gradient and the electrical gradient

The concentration gradient, the membrane thickness and the lipid solubility

The surface area, the membrane thickness and the membrane viscosity

The concentration gradient, the permeability constant and the viscosity