Question

Which of the following molecules can be considered as a lipid?
(A). Ubiquinone
(B). Retinol
(C). Dolichol
(D). $\beta$-Carotene
Choose the correct answer from the options given below:

• A. (A), (B) and (D) only.
• B. (B) and (D) only.
• C. (A), (B), (C) and (D).
• D. (B), (C) and (D) only.

Hint:

Isoprenoids (or terpenoids) represent the largest and most diverse class of plant lipids. They are built from five-carbon isoprene units and are highly hydrophobic.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Lipids are a diverse group of hydrophobic or amphipathic biological molecules.
This broad chemical class includes fats, waxes, sterols, fat-soluble vitamins, monoglycerides, diglycerides, triglycerides, phospholipids, and isoprenoids (terpenoids).

Step 2: Detailed Explanation:
Let us evaluate each of the given biomolecules:
- (A) Ubiquinone (Coenzyme Q): A lipid-soluble isoprenoid coenzyme with a hydrophobic polyisoprenoid tail. It acts as an electron carrier in the inner mitochondrial membrane.
- (B) Retinol (Vitamin A): A fat-soluble vitamin derived from isoprenoid precursors (diterpene).
- (C) Dolichol: A class of long-chain unsaturated organic compounds made of repeating isoprene units. It acts as a membrane-anchored lipid carrier for oligosaccharide synthesis.
- (D) $\beta$-Carotene: A highly lipophilic tetraterpene pigment that serves as a precursor of Vitamin A.
Because all four molecules are isoprenoids/terpenoids, they are all classified under the lipid category.

Step 3: Final Answer:
All four options (A), (B), (C), and (D) are lipids.