membrane lipid
Last reviewed 01/2018
The plasma membrane lipid is divided into three groups arranged in a bilayer:
- phospholipids:
- polar head group:
- site of phosphate residue
- it is hydrophilic and sits on outside of bilayer
- joined to 2 long chain fatty acids via glycerol
- fatty acids:
- 14-24 carbon atoms long
- hydrophobic
- sit on inside of membrane
- five key types:
- phosphatidylcholine; mainly in outer bilayer; used in arachidonic acid metabolism
- phosphatidylinositol; used in arachidonic acid metabolism
- sphingomyelin; mainly in outer bilayer
- phosphatidylserine; mainly in inner bilayer
- phosphatidylethanolamine; mainly in inner bilayer
- cholesterol:
- hydroxyl head sits on outside of bilayer
- steroid core interacts with hydrophobic interior of membrane
- increases strength and decreases fluidity of bilayer
- glycolipids:
- present on outside of bilayer leading to term 'cell coat'
- also termed the glycocalyx
- may act as immune recognition molecules and receptors for transmitters