Complexes of lipids and proteins responsible for transport and distribution of lipids in the lymph and blood are called

• A. Lipid droplets
• B. Albumin
• C. Glycoproteins
• D. Lipoproteins

Answer: (D)

Lipoproteins are the structures that allow lipids to travel through watery environments like lymph and blood by forming a particle with a hydrophobic lipid core surrounded by a polar surface. The core mainly contains triglycerides and cholesteryl esters, while the surface is made of phospholipids, free cholesterol, and specific proteins called apolipoproteins. This arrangement makes lipids soluble enough to circulate, and the types of lipoproteins (such as chylomicrons from the intestine, and VLDL, LDL, HDL from the liver) differ in density and composition, guiding delivery to tissues or removal from circulation. Chylomicrons enter the lymph as they transport dietary lipids; in blood they are processed into remnants. HDL is involved in reverse cholesterol transport, helpingreturn cholesterol to the liver. While albumin can bind free fatty acids and some lipids for transport, it does not form the lipid-protein complexes that circulate as lipoproteins. Lipid droplets are intracellular storage forms, not circulating carriers, and glycoproteins are proteins with carbohydrate attachments, not the lipid-carrying particles described here.