Membrane Structure

Question 1

Function of membrane

Answer 1

Selective permeable barrier
Allows control over enclosed chemical environment
Communication
Recognition (receptors of signalling molecules, self antigens, adhesion proteins for structure)
Signal generation from stimuli

Question 2

Membrane composition

Answer 2

Varies with source
Dry weight: 
40% lipid
60% protein 
Small carbohydrate 
20% water when hydrated

Question 3

What type of lipids make up membrane

Answer 3

Amphipathic - contain hydrophilic and hydrophobic groups

Question 4

Phospholipids

Answer 4

Main lipid of membrane
Polar Head group (choline, amine, AA, sugar)
Fatty acid chains (varied length usually C16-18)
Cis double bond between carbon = kink

Question 5

Other phospholipid in membrane

Answer 5

Sphingomyelin - a sphingolipid
(No glycerol backbone)
Glycolipid

Question 6

Types of glycolipids

Answer 6

Contain sugar
Cerebrosides - head group = sugar monomer
Gangliosides - head group = oligosaccharide (many)

Question 7

Lipid structures

Answer 7

Micelle - circular

Bilayer - sheet, stabilised by water hydrophobic tails inner, hydrophilic heads outside

Question 8

Phospholipid structure

Answer 8

Choline, phosphate head (hydrophilic)
Glycerol back bone
Fatty acid chain (hydrophobic)

Question 9

Phospholipid head group examples

Answer 9

Choline
Serine
Inositol
Ethanolamine