Lipoprotein,illustration. This is a low density lipoprotein (LDL),or 'bad' cholesterol,molecule. It consists of a core of esterified cholesterol molecules (yellow) surrounded by a shell of unesterified cholesterol (orange with violet cap) and phospholipids (orange with blue cap). The complex structure includes carrier proteins (blue) known as apo-B proteins,which assist transport in the blood. When there are high levels of LDL cholesterol in the blood it builds up on the sides of blood vessels hardening them,a condition named atherosclerosis. This narrows the blood vessels and may block them |