Membrane Structure and Function

Question 1

composition of membrane varies between organisms (and in same cell) in terms of ratio of ??? to protein, type of ??? and abundance and type of ???

Answer 1

lipid
phospholipid
sterol

Question 2

the phospholipid bilayer is not asymmetrical as both sides have different ratios/composition of lipid and protein which also affects ???, ???, and function (can mark cell for apoptosis)

Answer 2

fluidity
membrane potential (outside leaflet more negatively charged)

Question 3

Integral membrane proteins have a ??? domain and may span the whole membrane

Answer 3

have a hydrophobic domain

Question 4

Peripheral membrane proteins are associated with ??? or surface portions of the membrane lipids and proteins (easily removed)

Answer 4

hydrophilic

Question 5

amphitropic membrane proteins are sometimes associated with ??? and sometimes not

Answer 5

membranes

Question 6

membrane fluidity is determined by the ratio of unsaturated FAs to ??? FAs and the ??? of their chains

Answer 6

saturated fatty acids and the length of their chains

Question 7

TRUE or FALSE: hibernating animals will alter their membrane lipid composition in order to cope with low body temperatures (achieved through diet)

Answer 7

TRUE

Question 8

What is the role of sterols in membranes?
Hint: they buffer the transition from solid to a liquid or vice versa with temp changes

Answer 8

they act as a fluidity buffer

Question 9

Lateral diffusion: individual lipids undergo fast lateral diffusion within a single leaflet. speed depends on ???, lipid and sterol composition.

Answer 9

temperature

Question 10

Does lateral diffusion refer to/include membrane proteins as well?

Answer 10

YES

Question 11

Flip-Flop/ switching sides refers to when membrane lipids and/or proteins cross sides to the opposite leaflet. this is very ??? and requires more energy

Answer 11

VERY slow

Question 12

Translocating enzymes help to speed up ??? by using ATP => ADP + P

Answer 12

flip-flop movement

Question 13

Translocating enzyme Flipase: moves ??? from outer to inner leaflet

Answer 13

lipids/proteins

Question 14

Translocating enzyme Floppase: moves ??? from inner cytosolic to outer leaflet

Answer 14

lipids/proteins

Question 15

Translocating enzyme Scramblase: moves lipids in ??? direction, to gain equilibrium

Answer 15

either direction

Question 16

Passive diffusion refers to some small polar solutes, nonpolar compounds and some gases where they move along a ???

Answer 16

concentration gradient, from high to low

Question 17

Facilitated diffusion requires ??? to facilitate the transport of polar compounds down a ???
these are called permeases or transporters

Answer 17

proteins
concentration gradient

Question 18

Facilitated diffusion channels have a ??? shell and a polar interior

Answer 18

hydrophobic shell

Question 19

Active diffusion transports proteins ??? their concentration gradient and thus requires energy (ATP)

Answer 19

against

Question 20

Primary active transport requires the breakdown of ???

Answer 20

ATP

Question 21

Secondary active transport is when the movement of one solute down its concentration gradient drives the ??? of another solute

Answer 21

co-transport

Question 22

sodium-potassium pump is an example of what type of active transport?

Answer 22

secondary: active co-transport

Question 23

the sodium potassium pump works by maintaining a high internal ??? and low ??? relative to concentrations in blood, generating membrane potential necassary for electrical signalling

Answer 23

high potassium and low sodium