Lecture 6: Ion channels and the electrical properties of membranes

Question 1

How do aquaporins block the passage of ions?

Answer 1

Ion passage is blocked by energetically

disfavoring removal of the ion’s hydration shell

Question 2

How do aquaporins block the passage of protons?

Answer 2

Proton passage is blocked by strategic
hydrogen bonding of the oxygen atom of
water and Asn residues in the channel during
passage. This hydrogen bond prevents
hydronium ion (H3O+) formation

Question 3

___ channels are responsible for membrane
depolarization, generation and propagation of
action potentials, and membrane repolarization in electrically exitable cells

Answer 3

voltage-gated

Question 4

Membrane depolarization, a shift in membrane
potential to a less negative value, is generally
driven by voltage gated ___ channels (cation
channels)

Answer 4

Na+