chapter 3 // plasma membrane // structure

function of plasma membrane

• to be a barrier that separates the intracellular and extracellular environment

• to regulate the passage of substances

what is the plasma membrane

a semi-permeable lipid bilayer

fluid mosaic model

• fluid = phospholipids + some proteins move laterally

• mosaic = diverse

phospholipid structure

head = hydrophilic / polar

tail = hydrophobic / non-polar

• organised in a bilayer

integral protein

permanent part of membrane

transmembrane protein

protein that spans the entire bilayer

peripheral protein

temporarily attached protein

functions of proteins

• transport

• catalysis

• communication

• adhesion

glycoprotein

protein with carbohydrate attached

glycolipid

lipid with carbohydrate attached

function of glycoproteins + lipids

• cell recognition

• receptor binding sites

carbohydrates

• embedded in the membrane

• cell to cell communication, signalling, recognition of self, adhesion

cholesterol

• lipid embedded between fatty acid tails in animal cells

membrane damage

• ethanol (alcohol) = increases fluidity

• detergents

• higher temperatures

• changes in pH