How do LDL and HDL differ structurally and functionally?
The difference in LDL and HDL cause them to function in very different manners. LDL binds to cholesterol in the liver to carry it to cells in the body. The lack of density allows excess LDL to remain in the blood vessels. When blood vessels become damaged, LDL accumulates along the walls' of the vessel. More cholesterol in the blood the more LDL that builds up. This build up leads to plaque formation in a process called atherosclerosis. The high density of HDL keeps it moving through the blood vessels. When in goes through the vessels it picks up the excess cholesterol from the tissues of the blood vessels. HDL carries the cholesterol back to the liver. LDL is also structurally different to HDL. LDL is 50% cholesterol and 25% protein. HDL is 20% cholesterol and 50% protein. LDL proteins contain "B-100" proteins, while HDL contains "A-1" and "A-11" proteins. HDL molecules are larger than LDL molecules.