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The diagram below is a map of a bacterial plasmid showing ORI, the origin of DNA replication, and selected restriction endonuclease sites - VCE - SSCE Biology - Question 39 - 2019 - Paper 1
Question 39
The diagram below is a map of a bacterial plasmid showing ORI, the origin of DNA replication, and selected restriction endonuclease sites. One plasmid was mixed wit... show full transcript
Worked Solution & Example Answer:The diagram below is a map of a bacterial plasmid showing ORI, the origin of DNA replication, and selected restriction endonuclease sites - VCE - SSCE Biology - Question 39 - 2019 - Paper 1
Step 1
Which of the following shows the number of restriction sites that have been cut and the resulting number of DNA fragments produced?
Answer
To solve this problem, we need to analyze the restriction sites on the plasmid map provided, focusing on the enzymes used: EcoRI, BamHI, and HincII.
Step 1: Count the Restriction Sites
From the plasmid map, identify the positions of the restriction enzyme sites:
- EcoRI
- BamHI
- HincII
Upon reviewing the diagram, we will determine that:
- EcoRI cuts once (1 site)
- BamHI cuts once (1 site)
- HincII cuts once (1 site)
This totals to 3 restriction sites being cut.
Step 2: Calculate the Number of DNA Fragments Produced
When a plasmid is cut by restriction enzymes, the formula to calculate the number of DNA fragments produced is given by:
a = n + 1
where 'a' is the number of fragments and 'n' is the number of cuts made. Therefore:
- Given n = 3 cuts:
- The number of fragments would be:
a = 3 + 1 = 4
Conclusion
Thus, the final answer shows that 3 restriction sites are cut, producing 4 resulting DNA fragments. The correct option is C.