phospholipids

• phospholipids are made of one molecule of glycerol, one phosphate group and two fatty acids
• found in cell membranes
• the phosphate group is hydrophilic and the fatty acids are hydrophobic
• when mixed with water, the polar heads face outwards while the non-polar tails form an inner layer to protect the inside of cells from water
• their hydrophobic tails and hydrophilic heads mean they form a double layer with heads facing out towards the water
• centre of the bilayer is hydrophobic, so water soluble substances can't pass through it