Session 1: Membrane Bilayer Structure

Question 1

What are the main features of the fluid mosaic model of the cell membrane?

Answer 1

60% protein
40% lipid - amphipathic, mainly phospholipids
1-10% carbohydrates

Question 2

What are the major functions of the cell membrane? (6)

Answer 2

• Provide continuous, highly selective permeability barrier
• Controlling movement of specific molecules across membrane
• Enabling control of an internal highly dynamic chemical environment
• Signal generation in response to stimuli (electrical chemical)
• Communication: controlling flow of info between cells & internal environment of the body
• Recognition via signalling molecules, adhesion proteins & immune surveillance

Question 3

Why is water a major dynamic structure membrane component? (3)

Answer 3

• H bonds with water promote cholesterol adherence to challenging permeability
• H2O interacts with polar/charged regions of lipid head to stabilise
• Vital for structure & function