Question

The nutrient element essential for the synthesis of chlorophyll precursor in the biosynthesis of chlorophyll molecule:

• A. Mn
• B. Mo
• C. Fe
• D. Mg

Hint:

Be careful not to confuse the structural component of chlorophyll ($\text{Mg}$) with the catalytic elements required for its synthesis ($\text{Fe}$).
Iron is a classic cofactor for the enzymes that construct the porphyrin ring precursor.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
While Magnesium ($\text{Mg}$) is the central metal ion of the chlorophyll pyrrole ring, several other micronutrients are required as cofactors for the enzymes involved in its biosynthetic pathway.

Step 2: Detailed Explanation:
The biosynthesis of chlorophyll begins with the formation of $\delta$-aminolevulinic acid ($\text{ALA}$).
Several steps in the pathway, including the conversion of coproporphyrinogen to protoporphyrinogen and the formation of the isocyclic ring, require iron-dependent enzymes (e.g., coproporphyrinogen oxidase).
Iron ($\text{Fe}$) acts as an essential catalyst and cofactor for these early precursor synthesis steps.
Consequently, plants grown in iron-deficient environments fail to synthesize chlorophyll precursors and exhibit severe interveinal chlorosis, even if magnesium is abundant.

Step 3: Final Answer:
Iron ($\text{Fe}$) is the nutrient element essential for synthesizing the chlorophyll precursor.