Membrane Transport

Question 1

What are the two distinct types of transport proteins that mediate facilitated diffusion?

Answer 1

Channel and carrier proteins

Question 2

What are carrier proteins?

Answer 2

Integral glycoproteins which bind a solute and undergo a conformational change to translocate the solute across the membrane
Carrier proteins will only bind a specific molecule via an attachment similar to an enzyme-substrate interaction

Question 3

What are channel proteins?

Answer 3

Integral lipoproteins which contain a pore via which ions may cross from one side of the membrane to the other
Channel proteins are ion-selective and may be gated to regulate the passage of ions in response to certain stimuli
Channel proteins only move molecules along a concentration gradient (i.e. are not used in active transport)