Q.22 Terpenoids are made of ___________ units
(A) amino acid
(B) carbohydrate
(C) isoprene
(D) triacylglycerol
Terpenoids Are Made of Isoprene Units
Terpenoids consist of isoprene units, making option (C) the correct choice in this multiple-choice question. These natural compounds play key roles in plant biology and biochemistry, often studied in molecular biology and plant sciences.
Correct Answer
Terpenoids are made of isoprene units. (C) isoprene
Isoprene (C5H8) serves as the fundamental five-carbon building block for terpenoids, also called isoprenoids. Terpenoids form through head-to-tail linkages of these units, resulting in diverse structures like monoterpenes (two units, C10) and sesquiterpenes (three units, C15). This “isoprene rule” defines their classification and biosynthesis via pathways like mevalonate.
Option Analysis
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(A) amino acid: Amino acids build proteins through peptide bonds, not terpenoids, which derive from acetate via isopentenyl pyrophosphate.
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(B) carbohydrate: Carbohydrates form polysaccharides or energy stores like starch; terpenoids arise from lipid-like isoprene precursors, unrelated to sugar metabolism.
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(C) isoprene: Correct, as terpenoids assemble from multiple isoprene (C5) units, enabling vast structural variety in plants.
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(D) triacylglycerol: Triacylglycerols (triglycerides) store fats from glycerol and fatty acids; terpenoids lack this glycerol backbone.
Terpenoids in Plant Biology
Terpenoids function in plant defense, pigmentation (e.g., carotenoids), and scents, linking to your interests in plant sciences and biochemistry. Examples include limonene (monoterpenoid) and artemisinin (sesquiterpenoid lactone). Biosynthesis starts from isopentenyl diphosphate (IPP), emphasizing their non-amino acid, non-carbohydrate origin.
