Ultracentrifugation in lipoproteins is based on which property?

• A. Protein and TG content
• B. Lipid stains
• C. Creamy layer (chylomicrons); turbid (VLDL)
• D. Standing plasma test

Answer: (A)

Ultracentrifugation separates lipoproteins by density. Each particle’s density is determined by its lipid-to-protein ratio: more triglycerides lowers density, while more protein raises density. That’s why chylomicrons, rich in triglycerides, are the least dense, and HDL, with higher protein content and less lipid, is the most dense. The high-speed spins push particles to equilibrium positions in a density gradient, enabling separation into chylomicrons, VLDL, LDL, and HDL.

This aligns with the idea that composition—specifically protein and triglyceride content—drives the density differences used for separation. The other options describe visualization or non-centrifugation methods, which don’t explain the basis of the separation.