Components of Cell Surface Membranes Flashcards
Cell membranes contain several different types of molecules:
Three types of lipid:
Phospholipids
Cholesterol
Glycolipids (also containing carbohydrates)
Cell membranes contain several different types of molecules:
Two types of proteins:
Glycoproteins (also containing carbohydrates)
Other proteins (eg. transport proteins)
phospholipids structure and function
Form a bilayer (two layers of phospholipid molecules)
Hydrophobic tails (fatty acid chains) point in towards the membrane interior
Hydrophilic heads (phosphate groups) point out towards the membrane surface
Individual phospholipid molecules can move around within their own monolayers by diffusion
Cholesterol structure and function
Cholesterol molecules also have hydrophobic tails and hydrophilic heads
Fit between phospholipid molecules and orientated the same way (head out, tail in)
Are absent in prokaryotes membranes
Glycolipids structure and function
These are lipids with carbohydrate chains attached
These carbohydrate chains project out into whatever fluid is surrounding the cell (they are found on the outer phospholipid monolayer)
Glycoproteins: structure and function
These are proteins with carbohydrate chains attached
These carbohydrate chains also project out into whatever fluid is surrounding the cell (they are found on the outer phospholipid monolayer)
Intrinsic protein structure and function
The proteins embedded within the membrane are known as intrinsic proteins (or integral proteins)
They can be located in the inner or outer phospholipid monolayer
Most commonly, they span the entire membrane – these are known as transmembrane proteins
Transport proteins are an example of
transmembrane proteins as they cross the whole membrane
Proteins can also be found on the inner or outer surface of the membrane, these are known as
extrinsic proteins (or peripheral proteins)
