Question

Which of these is not a macromolecule?

• A. Starch (mol weight -- $2.27\times {10}^8$ Da).
• B. Collagen (mol weight -- 5,000 Da).
• C. Cholesterol (mol weight -- 386 Da).
• D. Vitamin A (mol weight -- 286 Da).

Answer 1

The correct option is D Vitamin A (mol weight -- 286 Da).

Biomolecules are classified as macro and micromolecules, depending on many factors, but the major one being their molecular size and weight. Generally, biomolecules weighing less than 800 Daltons are classified as micromolecules and those weighing above them, as macromolecules. But there are exceptions, primarily with fats and lipids. Lipids do not exist as individual molecules but as micelles or vesicles, of many molecules. Therefore they are neither acid soluble nor weigh less than 800 Daltons in vivo. Hence, even though cholesterol weighs less than 800 Daltons, it is still considered as a Macromolecule.