CUET Preparation Today
Which of the following statements is true about plasmids and bacteriophages in the context of genetic engineering?
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Plasmids and bacteriophages are unable to replicate independently within bacterial cells. Vectors are not engineered to assist in the linking of foreign DNA with bacterial DNA. Plasmid is an autonomously replicating circular extra-chromosomal DNA. Bacteriophages are always present in equal numbers to plasmids within bacterial cells. |
Plasmid is an autonomously replicating circular extra-chromosomal DNA. |
The correct answer is Option (3) – Plasmid is an autonomously replicating circular extra-chromosomal DNA. Plasmids and bacteriophages have the ability to replicate within bacterial cells independent of the control of chromosomal DNA. Plasmid is an autonomously replicating circular extra-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. |
