membrane structure and function I Flashcards
What does phosphatidylcholine do? [3 marks]
- Maintains structural integrity of the cell
- Involved in cell signalling
- Involved in enzyme activation
What does phosphatidylserine do? [1 mark]
Involved in apoptosis (signals to macrophages)
What does phosphatidylethanolamine do? [2 marks]
- Plays a part in membrane fusion
- Involved in disassembly of the contractile ring during cytokinesis
What does phosphatidylinositol do? [3 marks]
- Linked to a lipid (e.g. glycerophosphatidylinositol)
- Involved in cell signalling
- Plays a role in membrane trafficking
Cholesterol structure [3 marks]
- Large and flat
- Mostly hydrophibic
- Has polar -OH group
What are glycolipids important for? [2 marks]
- Cell recognition
- Membrane stability
Which phospholipids are usually found on the inner leaflet of the membrane? [2 marks]
- Sphingomyelin
- Phosphatidylserine
Which phospholipids are usually found on the outer leaflet of the membrane? [3 marks]
- Phosphatidylserine
- Phosphatidylethanolamine
- Phosphatidylinositol
How does temperature affect the fluidity of the membrane? [2 marks]
- High temperature: decreased fluidity
- Low temperature: increased fluidity
How does the composition of fatty acid affect fluidity of the membrane? [2 marks]
- Saturated fatty acids: more compact = low fluidity
- Mixture of fatty acids: less compact = high fluidity
How does chain length affect fluidity of the membrane? [2 marks]
- Short: less viscosity = more fluidity
- Long: more viscosity = less fluidity
Why do longer fatty acid tails affect fluidity of the membrane? [1 mark]
Higher chance of forming more intermolecular interactions
How does cholesterol content affect fluidity of the membrane? [1 mark]
Higher content = less fluidity
What does the ATP dependent flippase do when synthesising membranes? [1 mark]
Moves phospholipids from the outer to the inner leaflet
What does the ATP dependent floppase do when synthesising membranes? [1 mark]
Moves phospholipids from the inner to the outer leaflet
What does scramblase do when synthesising membranes? [1 mark]
Moves phospholipids in both directions
Structure of integral proteins [3 marks]
- Single OR multi pass
- Strong non-covalent bonds
- Trans-membrane domain (usually alpha helix)
What is a single pass in the context of membranes? [1 mark]
Where the molecule crosses through the membrane once (via integral proteins)
What is a multi pass in the context of membranes? [1 mark]
Where the molecule crosses through the membrane multiple times (via integral proteins)
What do integral proteins interact with? [1 mark]
Phospholipid bilayer
Peripheral proteins structure [2 marks]
- Either on extra-cellular or cytosolic membrane
- Weakly associated by non-covalent bonds
What do peripheral proteins interact with? [2 marks]
- Integral proteins
- Lipid polar head groups
What are lipid anchored membrane proteins? [1 mark]
Proteins that are covlanetly linked to a lipid (e.g. glycerophosphatidylinositol)
What is one example of a function for lipid anchored membrane proteins? [1 mark]
Blood groups
What are carbohydrates associated with in membranes? [2 mark]
- Membrane lipids
- Proteins
What are membrane carbohydrates involved in? [2 marks]
- Cell-cell interactions
- Cellular recognition
