Membrane Transport

Question 1

What percentage of membrane proteins are transport proteins?

Answer 1

15-30%

Question 2

What sort of molecules need to use membrane transport proteins to permeate the membrane?

Answer 2

charged and partially charged molecules

Question 3

What sort of molecules diffuse rapidly?

Answer 3

small, nonpolar molecules like O2 and CO2

Question 4

what sort of molecules diffuse slowly?

Answer 4

small, polar molecules like urea and H2O

Question 5

what prevents ions from diffusing through the membrane?

Answer 5

the degree of hydration and their charge

Question 6

Ions and polar molecules diffuse through the hydrophobic portion of the membrane how?

Answer 6

membrane transport proteins

Question 7

Are membrane transport proteins single or multi-pass?

Answer 7

multipass

Question 8

What is a transporter?

Answer 8

AKA carriers or permeases, these membrane transport proteins bind to the specific solute, and change their shape to alternately expose one side of the membrane then the other to allow the ion to pass through

Question 9

What is a channel?

Answer 9

form continuous pores that extend through the lipid bilayer which allows polar or charged molecules to diffuse down their concentration gradient

Question 10

Which facilitates a faster rate o diffusion, channels or transporters?

Answer 10

channels

Question 11

Why does active transport require energy from ATP?

Answer 11

because it moves molecules against their concentration gradients

Question 12

what drives passive transport?

Answer 12

the molecule’s concentration gradient

Question 13

What 3 things are true, regarding cations and anions, if the cell is negatively charged?

Answer 13

1. the entry of cations is favorable
2. the entry of anions is not
3. the efflux of cations is not

Question 14

What is the membrane potential?

Answer 14

a solutes concentration gradient and electrical potential difference across the membrane, forming the electrochemical gradient

Question 15

what is voltage

Answer 15

electrical potential

Question 16

which ions have a higher concentration outside the cell?

Answer 16

Na+, Mg2+, Ca2, and Cl-

Question 17

which ions have a larger concentration inside the cell?

Answer 17

K+ and H+

Question 18

What are the three Conformational orientations of the transporter proteins?

Answer 18

outward-open, occluded, inward-open

Question 19

What are the three ways cells perform active transport?

Answer 19

coupled transport, ATP driven pumps, light-driven pumps

Question 20

What is a is the difference between a antiport and a symport transporter?

Answer 20

A symporter brings the target molecules in the same direction (i.e. in or out of the membrane)

Question 21

What is the key similarity between antiporters and symporters?

Answer 21

They use the concentration gradient of one molecule/ion to drive another molecule/ion against its concentration gradient.

Question 22

At what ratio do Na-K pumps drive out Na+ ions to K+ ions?

Answer 22

3:2

Question 23

Is the cell more acidic or less acidic than the extracellular environment?

Answer 23

slightly more acidic

Question 24

How do cells generally regulate pH?

Answer 24

Na+-H+ exchangers

Question 25

Are membrane transporters uniformly distributed throughout a cell membrane?

Answer 25

No

Question 26

What are the two types of ATP pumps?

Answer 26

P-type pump and ABC transporter

Question 27

Describe the Ca2+ concentration in and around the cell

Answer 27

high in extracellular environment, high in SER and mitochondria, low in cytosol

Question 28

What three domains are attached to the Ca2+ pump?

Answer 28

nucleotide-binding domain, aspartic acid domain, activator domain