Session 2 ILOs - Transporters, Ion Channels & Pores 1

Question 1

What is a semi-permeable membrane?

Answer 1

A membrane through which only allowed substances can pass

Question 2

What types of molecules can permeate a lipid bilayer?

Answer 2

Hydrophobic (most permeable) or small & uncharged molecules
EXAMPLES: oxygen, water, glycerol, urea

Question 3

How do proteins contribute to membrane permeability? What are the different methods of transport?

Answer 3

They increase the membrane permeability to specific molecules, either by:

1. Carriers (‘ping pong’ mechanism)
2. Ligand gated channels
3. Voltage gated channels

Question 4

Where does the energy come from for membrane transport?

Answer 4

Either passive or active transport. If active transport, then energy comes from the hydrolysis of ATP

Question 5

How does water get through the lipid bilayer?

Answer 5

Water can move because it’s small & uncharged and it moves by diffusion. If rapid water transport is required, then aquaporins allow this to happen