CGP - Cell Membrane Structure

Question 1

Why is the bilateral called ‘fluid’?

Answer 1

Because the phospholipids are constantly moving.

Question 2

Why are cell membranes called ‘mosaic’?

Answer 2

Because proteins are scattered through the bilayer like tiles in a mosaic.

Question 3

Outline phospholipids.

Answer 3

Phospholipid molecules have

• a hydrophilic head : attracts water
• a hydrophobic tail : repels water

Heads face outwards in the bilayer
Tails face to the centre of the bilayer so the membrane doesn’t allow water soluble substances eg ions through.

Question 4

What does cholesterol do in the cell membrane?

Answer 4

It gives the membrane stability

Question 5

Where are cholesterol molecules found?

Answer 5

They fit between the phospholipids. They bind to the hydrophobic tails of the phospholipids, causing them to pack more closely together.