Question

Which one of the following is partly an isoprenoid derivative?

• A. Chlorophylls
• B. Glycerol
• C. Melanins
• D. Flavonoids

Hint:

Always remember that chlorophyll has a dual-ture structure: a nitrogenous porphyrin "head" (derived from glycine and succinyl-CoA) and a terpenoid/isoprenoid phytol "tail" (derived from isoprene units).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Isoprenoids (terpenoids) are a large and diverse class of turally occurring organic compounds derived from five-carbon isoprene units.
Key Principle:
Some complex biological pigments have hybrid structures, with one part of the molecule synthesized via the isoprenoid pathway and other parts synthesized through alterte metabolic routes.

Step 2: Detailed Explation:
Chlorophyll, the primary photosynthetic pigment in plants, consists of two main structural domains: a hydrophilic porphyrin ring and a highly hydrophobic hydrocarbon tail.
The porphyrin ring (chlorin ring) coordites a central magnesium ion and is synthesized via the tetrapyrrole pathway.
The long, hydrophobic tail consists of phytol, which is a 20-carbon branched-chain alcohol.
Phytol is synthesized directly from geranylgeranyl pyrophosphate via the plastidial methylerythritol phosphate (MEP) pathway, which is the primary route for isoprenoid synthesis.
Because the phytol tail is an acyclic diterpene, it is a direct isoprenoid derivative.
Since the phytol chain accounts for a significant portion of the chlorophyll molecule, chlorophyll is classified as being partly an isoprenoid derivative.
In contrast, Glycerol is a simple triol; Melanins are polymers derived from tyrosine; and Flavonoids are synthesized via the phenylpropanoid and malonic acid pathways.

Step 3: Fil Answer
Therefore, Chlorophyll is the correct option because its phytol tail is derived from the isoprenoid pathway.