Proteins in a cell membrane

Question 1

What are transmembrane proteins?

Answer 1

partially or fully cross the membrane
physically communicate across the membrane
may be linked to extracellular matrix or internal cytoskeleton

Question 2

What are the functions of membrane proteins?

Answer 2

selective transport- Ion channels and drug transporters
Receptors
-peptide hormones (eg. insulin)
-growth factors (lung cancer)
-cell attachment
-transmitting signals across a membrane

Question 3

What does “Fluid” in the Fluid Mosaic Model stand for?

Answer 3

Fluid is for motion and phase transitions

Question 4

Can the lipid in the bilayer move?

Answer 4

yes.

Question 5

What inhibits phase transitions making fluid less dynamic?

Answer 5

cholesterol, glycolipids and longer tails will make it LESS DYNAMIC.

Question 6

What is fluidity affected by?

Answer 6

its content, NOT temperature.

Question 7

What does “mosaic” refer to?

Answer 7

organization/diversity.

Question 8

What is the problem with cell integrity?

Answer 8

charged stuff inside of the cell attracts water
concentration inside of cell GREATER than outside

Question 9

what happens if there is no regulation inside of the cell?

Answer 9

the cell could swell and burst

Question 10

How do you regulate intracellular ions?

Answer 10

exchange ions, in and out to regulate the cell.
prevent changes in osmotic pressure
VIA CHANNELS, DIFFUSIONS (simple VS facilitated), AND PUMPS

Question 11

What are ion channels selective for?

Answer 11

size, channel, shape, diameter, and interior charges which affect the efficiency of movement in a channel (mainly shape and diameter).

Question 12

Membrane Transport- Simple Diffusion

Answer 12

simply goes right through a channel or right through the bilayer.
Rate dependent on concentration

Question 13

Hi gradient and Lo gradient in simple diffusion

Answer 13

hi gradient- gasses, O2 goes straight through the membrane
lo gradient- water, easily crosses, most common substance to cross.

Question 14

Facilitated Diffusion

Answer 14

requires interaction with a carrier protein (allows more control)

Question 15

what is a uniporter?

Answer 15

1 solute

Question 16

What is a symporter?

Answer 16

2 solutes going in the same direction

Question 17

What is antiporter?

Answer 17

2 solutes going in opposite directions

Question 18

Which way does the gradient for both simple and facilitated diffusion go from?

Answer 18

high to low. going along with the gradient.

Question 19

When does facilitated diffusion plateau?

Answer 19

when the amount of porters are limited. even if the concentration increases, it plateaus because it is FACILITATED diffusion.

Question 20

what is an example of a NON-diffusion movement

Answer 20

PUMPS- they can go against the gradient.

Question 21

What does active transport need?

Answer 21

a carrier protein, goes against its gradient (low to high), and needs energy (ATP)

Question 22

What is primary active transport?

Answer 22

primary active transport is energy breakdown from ATP (na/k+ pump)

Question 23

What is secondary active transport?

Answer 23

Gets its energy from ionic differences brought upon by primary active transport (glucose transporter)

Question 24

What in the body needs these pumps the most

Answer 24

heart, neurons, epithelial cells, small intestine
(cells that need to depolarize/repolarize a lot)

Question 25

What cells in the body dont need pumps?

Answer 25

red blood cells

Question 26

What is the moa of na/k+ pump

Answer 26

3 sodiums out of cell
2 potassiums into the cell

Question 27

what are the multiple steps that lead to cycling in the Na/K+ pump?

Answer 27

1. sodium binds inside
2. get ATPase activity
   3.phosphorylation causes a conformational change
3. 2K+ binds and causes dephosphorylation
   5.K also causes ANOTHER conformational change

Question 28

What does Digitalis Purpea do?

Answer 28

Digitalis binds to the extracellular domain of the pump blocking K+
inhibits the na/k+ pump
STOPS K+ from binding
now theres a build up of Na, that was forced to interact with the na/ca+ exchanger.

Question 29

What does the Na+/Ca+ exchanger do?

Answer 29

3 sodium out : 1 calcium in ratio
antiporter- ion concentration determines directions
uses facilitated diffusion
down gradient (high to low)

Question 30

What affect does digitalis have on the Na/Ca+ pump?

Answer 30

more intracellular calcium activates the actin- myosin complex
INCREASE IN HEART CONTRACTILITY
Bc increase of intracellular sodium, inhibits na/k+ pump which causes increase in intracellular calcium.

Question 31

Is the na/ca exchanger active transport or a type of diffusion?

Answer 31

facilitated diffusion, doesn’t need ATP

Question 32

is na/k+ pump active transport or a type of diffusion

Answer 32

primary active transport, NEEDS ATP

Question 33

Is the Na/glucose pump active transport or a type of diffusion

Answer 33

it is a symporter but is secondary active transport!

Question 34

What is purpose of the Na/glucose pump?

Answer 34

differential Na+ concentration, gut to cytoplasm, drives uphill transport of glucose

Question 35

What is a glucose uniporter?

Answer 35

facilitated diffusion

Question 36

Glucose integrates with 3 things, what are they?

Answer 36

na/K+ pump
na/glucose symporter- BUT ACTIVE
glucose uniporter