lecture 4 - membranes Flashcards
What is the very primary function of the cell membranes?
- barrier function
What are other functions of the barrier nature of the membrane?
- prevents loss of required metabolites
- protects against unwanted outside molecules
- capacitor function: stores electrical chemical energy
- Important for energy production and electrical signalling
How does the cell receive information?
receptors on cells surfaces receive information
What are 9 other functions of membrane proteins?
- selective permeability
- maintaining ionic composition
- maintaining cytoplasmic pH
- controlling osmotic pressure
- receptors
- cytoskeletal structures
- mediating matrix interactions
- carrying out enzymatic reaction
What type of molecule is a lipid?
- amphipathic molecule
Why do phospholipid bilayers form sealed compartments?
- Very energetically favourable , from liposomes
- Within a sealed compartment there are no hydrophobic ‘edges’ in contact with water
What are Glycerophospholipids?
- based on a 3 carbon glycerol.
- 2 carbons ester linked to fatty acids , one linked to a phosphate
What happens when the head group of a glycerophospholipid changes?
Nomenclature changes …so is called a phosphatidyl ….ect
What are 3 types of lipid found in membranes?
- Glycolipids
- Sterols
- Phospholipids
What is an example of a Glycolipid?
- sphingolipids , based on a long chain amino group
What is an example of sterols?
cholesterols
What is an example of a phospholipid?
Glycerophospholipids and sphingolipids
Can polar head groups flip from one leaflet to another in a lipid bilayer?
Not on its own, tend to be protein mediated.
Not energetically favourable for a polar head grow to flip as this requires a polar molecule moving through a hydrophobic environment
Why is membrane fluidity important?
- allows for fluidity for interactions to take place in the membrane
- compromises between rigid and ordered structure and completely fluid non - viscous liquid
What 4 factors influence membrane fluidity?
- temperature
- saturation of acyl chains
- length of acyl chains
- cholesterol
