The membrane bilayer: Structure

Question 1

what is the function of biological membranes

Answer 1

1) Continuous,highly selective permeability barrier
2) control of the enclosed chemical environment
3) communication
4) recognition of signalling molecules
5) signal generation in response to stimuli

Question 2

by dry weight what is the membrane composed of ?

Answer 2

60% protein
40% lipid
1-10% carbohydrate

Question 3

membrane are hydrated structures so how much water do they contain

Answer 3

20%

Question 4

describe the structure of a phospholipid

Answer 4

glycerol backbone attached to phosphate and head group(small)
glycerol backbone is attached to fatty acid tails

Question 5

name some phospholipid heads

Answer 5

choline
serine
ethanolamine
inositol

Question 6

what is a sphingolipid

Answer 6

lipid found in membrane
doesn’t have a glycerol backbone
synthesised by bringing together a fatty acid chain and sphingosine molecule

Question 7

how can glycolipids be classed

Answer 7

cerebroside (glycolipid with single monosaccharide head grp) and gangliosides(glycolipid with disaccharide head grp)

Question 8

role of cerebrosides

Answer 8

determine major blood groups

Question 9

role of gangliosides

Answer 9

important for function in CNS and are used by particles for invasion (cholera,flu)

Question 10

describe the structure of cholesterol

Answer 10

hydrophobic tail made up of 4 steroid rings. steroid ri nags are connected to a short 8 carbon tail. the hydrophilic head is a single hydroxy -OH group coming off the uppermost ring

Question 11

describe the lipid bilayer

Answer 11

a sea of lipid stabilised by interaction with H2O through hydrophilic heads and stabilisation of structure by hydrophobic interaction of the tails