cell membrane

Question 1

main functions of cell membrane

Answer 1

1. physical isolation
2. regulation of exchange with the environment
3. communication between the cell and its environment

Question 2

ion channels (leak channels)

Answer 2

for movement of small, charged particles (ions) across the membrane

• selective
• follow concentration gradient

Question 3

sodium potassium pump

Answer 3

• pumps 3 Na+ out of cell and 2 K+ into cell
• active transport (requires ATP) going against the transportation gradient
• essential as it maintains the concentration gradients

Question 4

gradients

Answer 4

concentration gradient

-molecules tend to move from area where there are high concentrations to low concentrations

electrical gradient

-tend to move toward areas of opposite charge

Question 5

membrane potential (Vm)

Answer 5

• all cells have a membrane potential
• it is the difference in electrical potential between interior and exterior of cell
• generated by selective permeability of the membrane to particular ions
• usually -70mv
• more Na outside and K inside
• SALTY BANANA

Question 6

movement of ions during membrane potential

Answer 6

• Na+ follow concentration gradient into cell
• Cl- follow concentration gradient into cell
• K+ follows concentration gradient to outside of cell

Question 7

is there more potassium leak channels or sodium leak channels?

Answer 7

• more potassium leak channels
• at _r_est cell membrane is more permeable to K+ ions

Question 8

membrane potential depends on

Answer 8

• concentration gradients of K+ and Na+
• Relative permeability of K+ and Na +

Question 9

equilibrium potential

Answer 9

-the electrical potential (mV inside the cell) which must be applied to exactly offset the force of the concentration gradient of the ion

Question 10

resting membrane potential

Answer 10

• exists across the plasma membrane and reflects the ionic differences between the cytoplasmic and extracellular sides of the membrane.
• leakage channels (non-gated ion channels ) and sodium-potassium pumps help maintain this polarized state

Question 11

Nernst equation

Answer 11

-measuring equilibrium potential (concentration and electrical gradient)

conditions :

1. membrane is permeable to 1 ion
2. must be a concentration gradient for the ion

Question 12

if you increase concentration of K+ inside the cell what happens to EK+?

Answer 12

it increases because concentration gradient increases. Need to oppose the force of K trying to exit the cell, so increase EK+ inside cell which pulls K+ back inside.

Question 13

if you increase Na+ concentration inside the cell, what happens to ENa+?

Answer 13

ENa+ would decrease because less Na will be coming inside cell because of concentration gradient. So less ENa+ is needed to pull Na+ back out of the cell.

Question 14

goldman-Hodkin-Katz equation

GHK

Answer 14

-how each ion will effect the resting membrane potential depending on its concentration gradient and permeability