Delayed-ripening tomato strategy: The trait was achieved by a biotechnologist who effectively __________ a key ripening gene (for example, polygalacturonase).
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Asilenced
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Brelocated
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Creplaced
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Doverexpressed
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Edeleted the entire genome
Answer
Correct Answer: silenced
Explanation
Introduction / Context:Delaying tomato ripening was achieved by reducing the expression of genes involved in softening, notably polygalacturonase. Early implementations used antisense RNA or co-suppression to silence gene expression.
Given Data / Assumptions:
- Polygalacturonase contributes to pectin breakdown.
- Antisense constructs reduce the target mRNA abundance.
- Goal is to slow, not abolish, ripening to maintain quality.
Concept / Approach:Gene silencing (by antisense or RNA interference) decreases enzyme levels without relocating or necessarily replacing the gene. This post-transcriptional approach is precise and preserves overall plant development.
Step-by-Step Solution:
Identify technique used historically: antisense suppression.Interpret outcome: reduced mRNA → less enzyme → delayed softening.Select term that best fits: silenced.Verification / Alternative check:Commercial and academic literature explicitly describes antisense-mediated silencing of the polygalacturonase gene in delayed-ripening tomatoes.
Why Other Options Are Wrong:
Relocated/replaced: not the mechanism; gene remained in place.Overexpressed: would accelerate, not delay, softening.Deleted the entire genome: nonsensical.Common Pitfalls:Equating gene knockout with silencing; early products used antisense rather than full knockouts.
Final Answer:silenced.