Membranes Flashcards
What does the cell surface membrane consist of?
A phospholipid bilayer with associated proteins.
What is the name of the cell membrane structure called?
The fluid mosaic model.
What are intrinsic proteins?
Proteins in the phospholipid bilayer which span both layers or are embedded into one layer.
What are extrinsic proteins?
Are attached to the membrane surface.
What can be sometimes found on the outside of the membrane?
Polysaccharides bound either to the proteins (glycoproteins) or to lipids (glycolipids). The polysaccharides are on the outer face only, where they form a fringe called the glycocalyx.
What factors influence the fluidity of a membrane?
The more phospholipids with unsaturated hydrocarbon chains, the more fluid the membrane is.
Temperature.
Cholesterol acts as a temperature stability buffer.
The length on hydrocarbon chains.
How does hydrocarbon chains being saturated effect the fluidity of a membrane?
The kinks in the unsaturated hydrocarbon tails prevent them from packing close together, so more movement is possible, so there is increased movement.
How does the length in hydrocarbon chains effect fluidity?
Phospholipids with longer hydrocarbon chains decrease the fluidity of the membrane, since attractive forces between the tails will be greater.
How does temperature effect fluidity?
The membrane is fluid at high temperatures and less fluid at low temperatures as the phospholipid bilayer ‘freezes’ into a gel or solid like state.
