Vectors: Plasmids and Bacteriophages — NEET Biology
✅ Asked in NEET 2023You know that plasmids and bacteriophages have the ability to replicate within bacterial cells independent of the control of chromosomal DNA. Bacteriophages because of their high number per cell, have very high copy numbers of their genome within the bacterial cells. Some plasmids may have only one or two copies per cell whereas others may have 15-100 copies per cell. Their numbers can go even higher. If we are able to link an alien piece of DNA with bacteriophage or plasmid DNA, we can multiply its numbers equal to the copy number of the plasmid or bacteriophage. Vectors used at present, are engineered in such a way that they help easy linking of foreign DNA and selection of recombinants from non-recombinants.
NTA tests your understanding of why plasmids and bacteriophages are ideal vectors for cloning foreign DNA. The key concept is that these vectors replicate independently and achieve multiple copies per cell—bacteriophages have very high copy numbers while plasmids range from 1-100+ copies. Students often confuse why we need such high copy numbers: it's to amplify the foreign DNA quickly without replicating the entire bacterial chromosome. Remember: vectors are specifically engineered tools that not only link foreign DNA but also allow easy selection of recombinants (cells that successfully incorporated the foreign DNA) from non-recombinants (cells without it). This distinction between vector function and selection is crucial for NEET questions.
Which of the following is not a cloning vector? (NEET 2023)
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