cell membrane structure

• main component of cell membranes is phospholipid molecules
• bilayer is fluid as phospholipids are constantly moving
• phospholipids form a continuous double layer (bilayer)
• proteins are found in the bilayer (mosaic), these include channel proteins and carrier proteins
• receptor proteins on the surface of the membrane allow the cell to detect chemicals released from other cells, causing the cell to respond in some way
• glycolipids and glycoproteins are also present
• the 'head' of the phospholipid is hydrophilic and the 'tail' is hydrophobic
• molecules automatically arrange in a bilayer with heads facing outwards towards the water
• centre of the membrane is hydrophobic so doesn't allow water-soluble molecules through
• cholesterol is a type of lipid
• cholesterol fits between the phospholipids, binding to the hydrocarbon tails
• cholesterol restricts the movement of phospholipid molecules as they cause the molecules to pack more closely together
• determine which substances pass through the membrane
• enables cells to stick together