L5

Question 1

describe primary active transport

Answer 1

the process follows the uphill graident.

this process has to be coupled directly to a continuous energy supply (ATP)

The movement of one solute is NOT coupled to the
downhill movement of another solute or water (this is secondary)

Question 2

describe how Na/K ATPase works

Answer 2

When ATP is bound its open to intracellular fluid

There are 3 Na binding sites

When they bind you get cleavage of ATP to ADP which releases energy which causes a conformational change and the protein will open to the extracellular fluid

Then K binds to the 2K binding sites

Then the phosphorus comes off and the protein has a conformational change the protein opens to the intracellular fluid and K is released

Question 3

what blocka Na/K ATPase

Answer 3

ouabain

Question 4

what do we need to determine if a charged species is active or passive

Answer 4

we need to sum the chemical and electrical gradients to determine the overall electrochemical graident

Question 5

when is the only time glucose can move up its concentration gradient

Answer 5

in the gut when it is coupled to Na

Question 6

how do you calculate the electrochemical graident

Answer 6

chemical potential - electrical potential

Question 7

what is the faraday’s constant

Answer 7

a conversion factor

Question 8

which cell have a static RMP and dynamic RMP

Answer 8

static = epithelial

dynamic = muscle

Question 9

what creates diffusion potentials

Answer 9

concentration greident and a selective membrane

Question 10

a large concentration difference = what kind of equilibrium potential

Answer 10

large equilibrium potential

Question 11

describe what happens in a cell that has a high conc of Cl- and K+ on one side of a semipermeable membrane (for K+ ions) and a low conc on the other side

Answer 11

Initially K will go to the other side

eventually
Then you get an electrical gradient for K to move back to the left

Eventually they will reach a happy point. This is the equilibrium potential

Question 12

what is the equilibrium potential at equilibrium

Answer 12

the chemical and electrical potentials are = but they are in opposing directions’

Question 13

what happens if the ratio of the concentration inside/outside the cell changes

Answer 13

then the membrane potential changes

Question 14

if there is an ion gradient across a membrane and the membrane is permeable to that ion. what 2 things could happen

Answer 14

the membrane potential will change to the equilibrium potential for that ion

or

if the potential is held at the equilibrium potential for that ion there will be no net movement of the ion across the membrane