Which of the following is an example of a plasmid vector used in genetic engineering?

pBR322

The correct answer is Option (1) –pBR322

The construction of the first recombinant DNA emerged from the possibility of linking a gene encoding antibiotic resistance with a native plasmid (autonomously replicating circular extra-chromosomal DNA) of Salmonella typhimurium. Stanley Cohen and Herbert Boyer accomplished this in 1972 by isolating the antibiotic resistance gene by cutting out a piece of DNA from a plasmid which was responsible for conferring antibiotic resistance.

In genetic engineering, a vector is a DNA molecule used to carry and transfer foreign DNA into a host cell. Plasmids are one of the common types of vectors used in genetic engineering experiments. They are small, circular DNA molecules that exist naturally in bacterial cells and can replicate independently of the chromosomal DNA.

Among the options provided, "pBR322" is an example of a plasmid vector. It is a well-known plasmid that has been extensively used in genetic engineering experiments.

By using plasmid vectors like pBR322, researchers can insert a piece of foreign DNA (a gene of interest) into the plasmid, creating a recombinant DNA molecule. When the recombinant plasmid is introduced into bacterial cells, it replicates along with the host cell's DNA, producing multiple copies of the inserted DNA. This allows scientists to produce a large quantity of the gene they are interested in studying or manipulating.

Overall, plasmid vectors like pBR322 are essential tools in genetic engineering, facilitating the introduction, replication, and expression of foreign DNA in host cells for various applications in biotechnology, medicine, and research.