Topic 32

Question 1

Which methods can be used to measure the membrane potential?

Answer 1

Electrophysiological methods

Potential Sensitive Staining

Question 2

Give the electrical measurements of membrane potential

Answer 2

Voltage Clamp

Patch Clamp

Question 3

Describe the voltage clamp method

Answer 3

Clamp continuously measures membrane potential.

Senses any difference

Emits an equal but opposite current, balancing out the membrane potential effect.

Current is then determined if constant.

Question 4

Describe the patch-clamp method

Answer 4

Measures individual channels

Patch pipette sucking cell membrane, measuring current flow.

The patch has 1µm diameter.

Channels selectively blocked by a specific toxin

Question 5

In optical measurements (potential sensitive staining), dyes belonging to the first group…

Answer 5

Change their spectroscopic properties in electric field

Question 6

In optical measurements (potential sensitive staining), dyes belonging to the second group…

Answer 6

Have negative or positive charges, distribute on two sides of a membrane.

If there is a change in membrane potential, there will be a change in dye distribution.