Recombinant DNA and Plasmid Vectors — NEET Biology
✅ Asked in NEET 2023'molecular scissors'– restriction enzymes. The cut piece of DNA was then linked with the plasmid DNA. These plasmid DNA act as vectors to transfer the piece of DNA attached to it. You probably know that mosquito acts as an insect vector to transfer the malarial parasite into human body. In the same way, a plasmid can be used as vector to deliver an alien piece of DNA into the host organism. The linking of antibiotic resistance gene with the plasmid vector became possible with the enzyme DNA ligase, which acts on cut DNA molecules and joins their ends. This makes a new combination of circular autonomously replicating DNA created in vitro and is known as recombinant DNA. When this DNA is transferred into Escherichia coli, a bacterium closely related to Salmonella, it could replicate using the new host's DNA polymerase enzyme and make multiple copies. The ability to multiply copies of antibiotic resistance gene in E. coli was called cloning of antibiotic resistance gene in E. coli.
NTA focuses on how restriction enzymes (molecular scissors) cut DNA and DNA ligase joins the cut ends to create recombinant DNA using plasmid vectors. Students often confuse plasmids with chromosomal DNA or forget that ligase is essential for joining fragments—restriction enzymes cut but cannot join. The key concept: plasmids are autonomously replicating vectors that carry foreign DNA into host cells (like E. coli), where the recombinant DNA replicates using the host's machinery. Remember the sequence: restriction enzyme cuts → DNA ligase joins → recombinant DNA forms → transferred to host → cloning occurs. This appears repeatedly in NEET because it's fundamental to genetic engineering.
This paragraph was tested 4 times in NEET.
Which of the following can act as molecular scissors? (NEET 2023)
Choose the correct pair from the following: (NEET 2020)
A foreign DNA and plasmid cut by the same restriction endonuclease can be joined to form a recombinant plasmid using: (NEET 2016)
The DNA molecule to which the gene of interest is integrated for cloning is called: (AIPMT 2015)
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
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