structure and function of plasma membrane Flashcards
functions of cell membrane
regulates what enters and exits the cell,
alters pH and charge
involved with cell recognition
major role in cell signalling e.g. from hormones
enzymatic functions
Aids in cell linking and cross-talk
describe the structure of the plasma membrane.
very thin membrane (7-8nm)
flexible yet sturdy barrier
structure best explained by the fluid mosaic model.
what is the fluid mosaic model.
Mosaic of free floating and attached proteins
Fluid lipid molecules
what does the membrane allow in and not allow in?
allows lipids
polar molecules arent allowed
what is the lipid bylayer?
what does it consist of?
- Forms the basic ‘fabric’ of the membrane
- It consists of:
- Phospholipids (75%)
- Cholesterol (20%)
- Polar Glycolipids in the external layer (5%)
what special properties does Polar Glycolipids
amphipathic
why does membrane fluidity occur? why is it importent
Neighbouring lipid molecules swap places
10 million times per sec
allows the movement of membrane components required for cell movement, growth, division, secretion and the formation of cellular junctions
what does cholesterol do in the bilyer.
Cholesterol immobilises the first few hydrocarbon groups of the phospholipids molecules.
why is cholesterol importent ?
makes the lipid bilayer less deformable
decreases its permeability to small water-soluble molecules.
what is the glycocalyx
Many are glycoprotein’s containing associated oligosaccharides
Form the glycocalyx
whats the function of glycocalyx
Required for detection of ‘self’ in immunity
Aids in cell- cell adhesion
Makes RBCs slippery and protects the GI from drying out
what are the different types of membrane proteins
Transport ( intrinsic and all the way through)
achors( proeteins connecting one another on the outside of membrane )
recepters (recepter binding site in the extracellular space)
enzymes (active site in cytosol)
