What is the principal function of lipoproteins?

What is the principal function of lipoproteins?

• A. transport lipids into bloodstream
• B. synthesize cholesterol in the liver
• C. digest lipids in the stomach
• D. break down lipids in lysosomes

Answer: (A)

Lipoproteins act as transport vehicles for lipids in the bloodstream because lipids are hydrophobic and don’t dissolve in water. Each particle has a core of triglycerides and cholesterol esters and a surface made of phospholipids, free cholesterol, and specific apolipoproteins. This design lets dietary fats enter the circulation (via chylomicrons) and liver-derived lipids (via VLDL, LDL, and HDL) be carried to tissues that need them or to the liver for disposal. So the main function is to move lipids through the bloodstream. Other options describe processes lipoproteins don’t perform: cholesterol synthesis occurs in the liver via enzymes like HMG-CoA reductase; lipid digestion is carried out by gastric and pancreatic lipases in the gut; lipid breakdown in lysosomes is done by lysosomal lipases inside cells.

Lipoproteins act as transport vehicles for lipids in the bloodstream because lipids are hydrophobic and don’t dissolve in water. Each particle has a core of triglycerides and cholesterol esters and a surface made of phospholipids, free cholesterol, and specific apolipoproteins. This design lets dietary fats enter the circulation (via chylomicrons) and liver-derived lipids (via VLDL, LDL, and HDL) be carried to tissues that need them or to the liver for disposal. So the main function is to move lipids through the bloodstream.

Other options describe processes lipoproteins don’t perform: cholesterol synthesis occurs in the liver via enzymes like HMG-CoA reductase; lipid digestion is carried out by gastric and pancreatic lipases in the gut; lipid breakdown in lysosomes is done by lysosomal lipases inside cells.