Given below are two statements: Statement I: Large subunit of rubisco is encoded by chloroplast genome while small subunit of Rubisco is encoded by…
Given below are two statements:Statement I: Large subunit of rubisco is encoded by chloroplast genome while small subunit of Rubisco is encoded by nuclear genomeStatement II: Small subunit of rubisco has a transit peptide, which is cleaved off at the time of its translocation into plastids.Choose the correct answer from the options given below:
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Correct Answer: Option A
Explanation
Rubisco subunit encoding — nuclear vs. chloroplast genome:Rubisco (Ribulose-1,5-bisphosphate Carboxylase/Oxygenase) is the key enzyme in carbon fixation (Calvin cycle):Subunit composition of form I Rubisco (plants, most organisms):• L (Large) subunit: CHLOROPLAST-encoded (rbcL gene in the plastid genome).- ~55 kDa; contains the active site for CO₂ fixation.• S (Small) subunit: NUCLEAR-encoded (rbcS genes).- ~15 kDa; translated in cytosol with a transit peptide for import into the chloroplast stroma.- Transit peptide is cleaved upon import.- Assembly: (L2S2)₄ → hexadecameric complex (L8S8)This split encoding is an important example of the coordination between nuclear and plastid genomes.Answer: Rubisco large subunit (rbcL) = chloroplast genome; small subunit (rbcS) = nuclear genome (with transit peptide for chloroplast import).