Membrane Transport

Question 1

What is the name of the model of the cell membrane?

Answer 1

The fluid mosaic model

Question 2

What are the features of the cell membrane?

Answer 2

Phospholipid bilayer, cholesterol, glycolipids, glycoproteins, intrinsic proteins, channel proteins (including aquaporins), carrier proteins, cell adhesion protein

Question 3

Describe the phospholipid bilayer

Answer 3

Two layers of phospholipids, lined up with the (hydrophobic) lipid tails pointing inwards, and the (hydrophilic) phosphate head pointing outward. This gives its fluidity, and the hydrophobic lipid gives it the barrier to aqueous environments.

Question 4

Describe cholesterol

Answer 4

It acts as a fluidity buffer, preventing excessive fatty acid mobility, lowering fluidity.

Question 5

Describe glycoproteins and glycolipids

Answer 5

Either proteins or lipids with carbohydrate chains attached. Involved in cell signalling and cell-cell recognition. GP act as receptors for hormones and chemicals, and GL help stabilise cell structure in addition.

Question 6

Describe channel proteins

Answer 6

Intrinsic proteins that provide a channel for water-soluble/polar and/or large molecules between the cell and an aqueous environment, or two adjacent cells.

Question 7

What is Ficks law?

Answer 7

Rate of diffusion is proportional to (surface area x concentration gradient)/diffusion distance