NEET 2026
- Exam
- NEET
- Year
- 2026
- Subject
- Biology
- Chapter
- Chapter
NEET 2026 · Biology · Chapter
During a gene cloning experiment, a researcher digests the plasmid...
During a gene cloning experiment, a researcher digests the plasmid vector with the restriction enzyme EcoRI and the target alien DNA with BamHI. When these two digested DNA samples are mixed along with DNA ligase, which of the following is the most likely outcome?
Options
- ARecombinant DNA will be formed efficiently because DNA ligase can join any two DNA fragments regardless of their ends.
- BThe formation of recombinant DNA will fail because the sticky ends produced by the two different enzymes are not complementary.
- CThe alien DNA will integrate into the plasmid because all restriction endonucleases produce the exact same overhanging sequences.
- DThe plasmid and alien DNA will successfully join only if they are treated with Taq polymerase before ligation.
Correct answer
B. The formation of recombinant DNA will fail because the sticky ends produced by the two different enzymes are not complementary.
Step-by-step solution
Restriction enzymes recognize specific DNA sequences and cleave them to produce specific sticky or blunt ends.
The restriction enzyme EcoRI recognizes the sequence 5'-GAATTC-3' and produces sticky ends with the overhang 5'-AATT-3'.
The restriction enzyme BamHI recognizes the sequence 5'-GGATCC-3' and produces sticky ends with the overhang 5'-GATC-3'.
For DNA ligase to successfully join two DNA fragments with sticky ends, the overhangs must be complementary so they can base-pair with each other.
Since the sticky ends produced by EcoRI and BamHI are not complementary, they will not base-pair, and DNA ligase will not be able to join the plasmid vector and the alien DNA.
Therefore, the formation of recombinant DNA will fail.
Answer: The formation of recombinant DNA will fail because the sticky ends produced by the two different enzymes are not complementary.
The restriction enzyme EcoRI recognizes the sequence 5'-GAATTC-3' and produces sticky ends with the overhang 5'-AATT-3'.
The restriction enzyme BamHI recognizes the sequence 5'-GGATCC-3' and produces sticky ends with the overhang 5'-GATC-3'.
For DNA ligase to successfully join two DNA fragments with sticky ends, the overhangs must be complementary so they can base-pair with each other.
Since the sticky ends produced by EcoRI and BamHI are not complementary, they will not base-pair, and DNA ligase will not be able to join the plasmid vector and the alien DNA.
Therefore, the formation of recombinant DNA will fail.
Answer: The formation of recombinant DNA will fail because the sticky ends produced by the two different enzymes are not complementary.