S2 Flashcards
What are the roles of lipid membranes? (5)
- Compartmentalisation
- Selective permeable barrier
- Signal generation in response to stimuli
- Communication
- Recognition of different cells
What is the composition of the membrane
60% protein
40% lipid
1-10% carbs
(20% water when hydrated)
What is an amphipathic molecule
Hydrophobic and hydrophilic parts
What is the structure of a phospholipid
2 fatty acid tails, glycerol, phosphate and head group
What is the phospholipid with choline as the head group
Phosphotidylcholine
What is a cerebroside
Phospholipid with head group and phosphate replaced by a monosaccharide
What is a ganglioside
Phospholipid with head group and phosphate replaced by an oligosaccharide
Four modes of phospholipid movement
Rotation
Flexion
Lateral diffusion
Flip-flop
Structure of cholesterol
Fatty acid tail
Rigid sterol rings
Polar head group
How does cholesterol interact with the lipid bilayer
Polar head group attracts glycerol on phospholipids
How does cholesterol affect membrane stability at high and low temperatures
Low: Stops phospholipids from packing to tightly (bulky rings act as spacers)
High: Keeps the membrane stable by restricting the movement of phospholipids
What is the functional evidence for membrane proteins? (3)
- Facilitated diffusion
- Specificity of cell responses
- Ion gradients
What is the biochemical evidence for membrane proteins? (2)
- Membrane fractionation + gel electrophoresis
- Freeze fracture
Movement of membrane proteins (3)
Conformational change
Rotation
Lateral diffusion
Restrictions of membrane protein movement (5)
Aggregation Tethering Interactions with other cells Intra and extra membranous (cytoskeleton) protein associations Lipid mediated effects
