the membrane bilayer

Question 1

functions of the membrane bilayer

Answer 1

communication
control a stable environment
signal generation
recognition proteins (immune system)

Question 2

percentage composition of the membrane

Answer 2

60%= protein
40% = lipid
1-10% = carbohydrate
(this is dehydrated before this 20% was water)

Question 3

features of phospholipids

Answer 3

they are ampiphatic. hydrophilic phosphate head attached to 2 hydrophobic hydrophobic chains and a glycerol

Question 4

variations of phospholipids

Answer 4

may have different amine, choline or sugars attached to head. e.g with choline= sphingomyelin and with sugar chain= phosphoglyceride. fatty acids may also vary in chain length and whether or not they are saturated

Question 5

what happens if a lipid is unsaturated

Answer 5

this means there are some double bonds in the rain causing it to kink so when next to each other they can’t pack properly

Question 6

what is a lipid micelle

Answer 6

a circle made of lipids

Question 7

types of phospholipid motion within the bilayer

Answer 7

flexion, rotation, lateral and flip flop

Question 8

what are glycolipids

Answer 8

1 sugar attached to lipid= cerebroside

2 sugars attached to lipid= ganglioside

Question 9

structure of cholesterol

Answer 9

rigid ring structure with a polar head and a non-polar hydrocarbon tail

Question 10

role of cholesterol and how it does this

Answer 10

control fluidity of membrane. It has OH groups that form H bonds with COOH on fatty acids and weakly holds it together but also have rigid tails which reduce movement by lateral motion and also prevents them packing . increases and decreases fluidity at the same time.

Question 11

how cholesterol removes the endothermic transition phase

Answer 11

usually on a graph there is a sharp increase when structure moves from crystalline to lipid but as more cholesterol is added there is less movement of phospholipids as temp increases