Capacity of λ Charon 34 and Charon 35 vectors Up to what insert size can the lambda vectors Charon 34 and Charon 35 reliably clone DNA?
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A1–2 kb
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B6–7 kb
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C9–20 kb
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D30–35 kb
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E50–60 kb
Answer
Correct Answer: 9–20 kb
Explanation
Introduction / Context:Charon series vectors are engineered λ phage replacement vectors used historically for genomic libraries. Knowing typical insert capacities is key for choosing appropriate vectors in classical cloning workflows.
Given Data / Assumptions:
- λ replacement vectors accept larger inserts than insertion vectors.
- Packaging constraints limit total genome length within defined bounds.
- Charon 34/35 are examples used in many early library constructions.
Concept / Approach:For λ replacement vectors like Charon 34 and 35, stuffer removal allows inserts roughly in the 9–20 kb range while maintaining efficient packaging. Inserts smaller than ~9 kb or larger than ~20 kb risk poor packaging and plaque formation failure.
Step-by-Step Solution:
Match vector class (replacement) to typical capacity.Recall the accepted window for these specific Charon vectors: ~9–20 kb.Select the answer reflecting this range.Verification / Alternative check:Historical protocols and manuals report successful cloning within ~10–20 kb for these vectors, aligning with the chosen range.
Why Other Options Are Wrong:
- 1–2 kb or 6–7 kb are too small (insertion vector territory).
- 30–35 kb and above exceed λ packaging tolerance.
Common Pitfalls:Ignoring both minimum and maximum packaging thresholds leads to failed library construction.
Final Answer:9–20 kb