Lecture 1.4: Transport and Channels

Question 1

What is the difference between channels and transporters/pumps?

Answer 1

Channels faclitate diffusion of ions and water molecules down their concentration gradients. Ion channels in specific can function without a single gate and the movement of ions is usually fast. Transporters move ions down their concentration gradients and pumps use ATP (energy) to move ions up their concentration gradients.

Question 2

Why can only one gate of transpoters/pumps be open at a time? What happens when more than one gate(s) are open?

Answer 2

If more than one gate is open at a time, ions will begin to go back up their concentration gradients. This is why pumps and transporters are slower than channels

Question 3

Two of the most important pumps in mammalian cells?

Answer 3

Na+ and K+

Question 4

Why is it necessary to have two different ion channels for Na+ and K+ when they can both go through an ion channel?

Answer 4

Na+ flow can only create an outward current and K+ flow can only create an inward current. The flow of Na+ and K+ depends on the concentration gradients on both sides of the membrane.