DNA fragments from diverse sources can indeed be cloned into plasmids, a cornerstone of recombinant DNA technology. Plasmids facilitate this through standard molecular biology techniques, independent of their transfer mechanisms.
Correct Answer
Both (A) and (R) are correct but (R) is not the correct explanation of (A).
Assertion (A) Explanation
Any DNA fragment can be cloned into a plasmid vector after compatible restriction enzyme digestion or PCR amplification with appropriate overhangs, followed by ligation using T4 DNA ligase to form recombinant plasmids. This universality stems from standardized multiple cloning sites (MCS) in plasmids like pUC19 or pBR322, which accommodate fragments from bacterial, eukaryotic, viral, or synthetic sources regardless of origin.
Reason (R) Explanation
Plasmids transfer to recipient cells via transformation (e.g., heat shock or electroporation in lab settings), conjugation (natural bacterial plasmid transfer), or transduction (phage-mediated). These mechanisms enable plasmid propagation and amplification in host cells like E. coli, but they occur post-cloning.
Why R Doesn’t Explain A
Cloning (A) is a benchtop enzymatic process: insert preparation, vector linearization, ligation—completed in vitro before any cell transfer. Reason (R) describes downstream delivery/amplification, not the insertion mechanism itself.
Options Breakdown
| Option |
Description |
Correct? |
| Both correct; R explains A |
Claims transfer enables cloning |
❌ No; transfer follows cloning |
| Both correct; R does not explain A |
True statements without causal link |
✅ Correct |
| A correct; R incorrect |
Denies plasmid transfer reality |
❌ R is true |
| A incorrect; R correct |
Denies universal cloning |
❌ A is true |
