The Cell Membrane (Thursday)

Question 1

What makes each protein unique and gives it its form and function?

Answer 1

R groups

Question 2

What is a primary structure of a polypeptide like?

Answer 2

it’s a chain of linked amino acids

Question 3

What is a secondary structure of a polypeptide like?

Answer 3

the chain coils into a 3D structure

Question 4

What is a tertiary structure of a polypeptide like?

Answer 4

the chains fold into a more-complex subunit

Question 5

What is a quaternary structure of a polypeptide like?

Answer 5

multiple subunits fold into one ion channel

Question 6

What are three things we should know about proteins?

Answer 6

1. they usually consist of 4-6 subunits, 2. are selective to certain ions, and 3. may use gating (which is activating under certain circumstances)

Question 7

What is a ligand-gated ion channel’s purpose?

Answer 7

a ligand (or ionotropic receptor) interacts with the ion channel which opens it

Question 8

What is a voltage-gated ion channel’s purpose?

Answer 8

once an action potential is reached, it opens the gate

Question 9

How does the permeability of potassium work to NOT let other ions in?

Answer 9

CTX plug the ion channel which pushes it out

Question 10

What is does the sodium-potassium pump like?

Answer 10

it pumps three sodium ions out in place of two potassium ions going in, however it requires a lot of ATP to formulate energy

Question 11

In a sodium-potassium pump, which of the two counterparts has a higher concentration on the outside and inside?

Answer 11

former has more sodium while the latter has more potassium

Question 12

What does the plasma membrane CA 2+ ATP-ase do?

Answer 12

it breaks down ATP to remove calcium ions

Question 13

What does the sodium-calcium exchanger do?

Answer 13

it uses energy from sodium flowing down to exchange calcium

Question 14

How do you determine the membrane voltage with equally permeable ion channels? (say two potassium and sodium channels as an example)

Answer 14

they would be the average of both the potentials between potassium and sodium

Question 15

How do you determine the membrane voltage with NOT equally permeable ion channels? (say 40x potassium than sodium channels as an example)

Answer 15

the membrane voltage would be closer to potassium’s potential

Question 16

What would happen if the membrane was only permeable to potassium?

Answer 16

it would only equate to the potential for potassium

Question 17

What would happen if the membrane was permeable to both potassium and sodium (not chloride) but potassium is 40x stronger?

Answer 17

the potential would be closer to potassium’s potential

Question 18

What happens when you increase extracellular potassium?

Answer 18

the membrane would depolarize which would then lead to an action potential

Question 19

What is the purpose of potassium spatial buffering?

Answer 19

it regulates extracellular potassium concentrations (which could lead to to lack/overstimulation of signals which makes communication more difficult)

Question 20

How does potassium spatial buffering regulate potassium?

Answer 20

it either temporarily accumulates and stores potassium or it spreads it to other extracellular areas with less potassium