2 - Membrane Potentials

Question 1

Describe the difference between monovalent and divalent cations and anions

Answer 1

Monovalent = valency of 1
Divalent = valency of 2
Cations = positive
Anions = neg

Question 2

What do you need to predict the polarity of membrane potential?

Answer 2

Know what ion channels are open and the relative conc of these ions inside and outside of the cell

Question 3

What does the magnitude of membrane potential dependent on?

Answer 3

Size of conc gradient of the ion across the membrane

Question 4

What does the magnitude of membrane potential dependent on?

Answer 4

Size of conc gradient of the ion across the membrane

Question 5

What is an equilibrium potential?

Answer 5

potential difference across the membrane that will exist after equilibrium is achieved.

Question 6

What is the Nernst equation?

Answer 6

Question 7

What is the history behind Nernst equation

Answer 7

Named after Walther Nernst who was awarded a nobel prize in 1920 for his contributions to electrochemistry

Question 8

Describe the term potential difference

Answer 8

The difference in charge between 2 points
Measured w/ voltmeter

Question 9

Explain membrane potentials and how do you measure it?

Answer 9

• Potential difference across the membrane
• Can vary from cell to cell and with time
• Measured with a voltmeter with fine leads (microelectrodes)
• 1 inside the cell and 1 outside

Question 10

What is the fundamental assumption when using Nernst equation?

Answer 10

That the membrane is selectively permeable to 1 ion species

Question 11

What is the difference between concentration and electrical gradients?

Answer 11

• EG is an electrical potential that acts on an ion to drive the movement of the ion in a direction. Forms from difference in charge on opposite sides of the membrane.
• CG is when the conc of molecules is higher in one area than another.