23. First committed precursor in biosynthesis of chlorophyll is:
(1) delta-aminolevulinic acid (2) Porphobilinogen
(3) Protoporphyrin IX (4) coproporphyrinogen III
The first committed precursor in the biosynthesis of chlorophyll is delta-aminolevulinic acid (ALA).
Explanation of options:
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(1) Delta-aminolevulinic acid (ALA) is the first committed precursor formed from glutamate or glycine and succinyl-CoA. It initiates the tetrapyrrole biosynthesis pathway leading to chlorophyll.
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(2) Porphobilinogen is formed from ALA later in the pathway, so it is a downstream intermediate.
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(3) Protoporphyrin IX is a later intermediate where Mg2+ insertion commits the pathway towards chlorophyll biosynthesis.
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(4) Coproporphyrinogen III is also an intermediate occurring after porphobilinogen formation but before protoporphyrin IX.
Thus, ALA marks the committed step starting chlorophyll biosynthesis, critical in plant physiology and photosynthesis research.
Focus keyphrase: delta-aminolevulinic acid chlorophyll biosynthesis precursor
Slug: delta-aminolevulinic-acid-chlorophyll-biosynthesis-precursor
Meta description: Discover why delta-aminolevulinic acid (ALA) is the first committed precursor in chlorophyll biosynthesis, initiating the pathway that leads to the essential photosynthetic pigment in plants.
