Lecture 1: Intro Concepts

Question 1

Membranes _________ and _________ different environments

Answer 1

Compartmentalise and Seperate

Question 2

How thick in the cell membrane?

Answer 2

~10nm

Question 3

Does thickness affect the electric field?

Answer 3

Yes, the relationship is inverse squared

Question 4

What influences diffusion rates?

Answer 4

Size
Solubility
Availability of transporter/channels

Question 5

What are the 3 types pumps?

Answer 5

Uniport (1 molecule)
Symport (2 different molecules in same direction)
Antiport (2 different molecules in opposite directions)

Question 6

________ channels are always open

Answer 6

Leakage

Question 7

What are the 3 types of channel gated

Answer 7

Voltage
Ligand
Stretch

Question 8

What is the major force acting on ions and molecules in the cell?

Answer 8

Membrane Potential

Question 9

What contributes to the Membrane Potential?

Answer 9

Trapped Anions
Na/K pump
Cell membrane is preferentially permeable to K+ (Biggest Factor)

Question 10

Voltage is generated without significant change in _______________ and is directly proportional to _______________.

Answer 10

[gradient]

[gradient]

Question 11

What is the elementary charge (q) of a proton/electron?

Answer 11

1.6 x 10^-19

Question 12

What is Faraday’s Constant?

Answer 12

96485 C/mol

Question 13

The charge on x Moles of an ion of valence A is ________.

Answer 13

xAF
i.e. Na+ = F
Cl- = -F
Ca^2+ = 2F

Question 14

What is the formula for Q = ……..?

Answer 14

Q = zFn
z = valence
n = no. of moles

Question 15

1 Volt is equivalent to the energy needed to ______________________________________.

Answer 15

move 1C a distance of 1m against a force of 1N

Question 16

What is conductance?

Answer 16

The ease with which an electrical current passes = 1/R (units of Siemens)

Question 17

What is the resistance of a pure phospholipid bilayer?

Answer 17

10^15 Ω.cm

Question 18

What is capacity?

Answer 18

The ability to store charge of opposite signs on conducting plates separated by an insulating layer (Measured in Farads = 1C/V)

Question 19

How is Capacitance symbolised?

Answer 19

C

Question 20

The Voltage developed across a capacitor is equal to…….

Answer 20

V = Q/C or Q = CV

Question 21

What is the capacitance of the membrane?

Answer 21

1μF/cm^2

Question 22

What is Δμx?

Answer 22

Electrochemical Potential energy difference (driving force)

Question 23

Δμx = _________ + _________

Answer 23

Chemical potential + Electrical Potential
RT * ln( [x]in/[x]out ) + zF(ψin - ψout)

ψin - ψout = membrane potential

Question 24

What is the Nernst equation?

Answer 24

Ex = -2.303 *(RT/zF) * log( [x]in/[x]out )

Ex = Driving force for x

Question 25

What happens when the driving force equals the membrane potential?

Answer 25

When Ex = Vm their value is the equilibrium potential

Question 26

How is the net flow of ions calculated?

Answer 26

Ix = Gx (Vm - Ex)

Ix = current of x 
Gx = conductance for x