L4 - Electrochemical Gradients

Question 1

Why to ions spread out?

Answer 1

Thermal agitation

Avg. center to center distance = 2.8A (1A=0.1nm)

Question 2

Proportion of ion spread is due to… and the dimension?

Answer 2

Proportional to:
Area of interface
Conc of gradient

Random walk

3D: further as less likely to collide

2D: greater collision (how catalyst work)

Question 3

What is the movement of ions due to an electric field?

Answer 3

Electrophoretic

Electrochemical gradient

Question 4

4 factors that effect the RATE of ion movement through ion channels

and 3 electrical concepts

Answer 4

1. Size of gradient
2. Nature of ion
3. No. of open channels
4. Properties of channel

a. Current is flow of ions
b. Voltage is potential diff
c. Resistance

Question 5

Ohm’s Law

Answer 5

Current (I) = Volts (V)/Resistance (R)

Current (I) = Volts (V) X Conductance

Question 6

Why are electrophysiological recordings made?

Answer 6

Extremely fast
Extremely sensitive
Spatial resolution
Individual channels