Read the following passage carefully and answer the given questions.

DNA recombinant technology involves the use of restriction endonucleases. After having cloned the gene of interest and having optimised the conditions to induce the expression of the target protein, one has to consider producing it on a large scale. The cells harbouring cloned genes of interest may be grown on a small scale in the laboratory. In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning. In Biolistics or gene gun method cells are bombarded with high velocity micro particles of gold or tungsten coated with DNA. The ligation of alien DNA is carried out at a restriction site present in one of the two antibiotic resistance genes. For example, you can ligate a foreign DNA at the BamHI site of tetracycline resistance gene in the vector pBR322. Since the DNA is enclosed within the membranes, we have to break the cell open to release DNA along with other macromolecules such as RNA, proteins, polysaccharides and also lipids. The RNA can be removed by treatment with ribonuclease whereas proteins can be removed by treatment with protease. Other molecules can be removed by appropriate treatments and purified DNA ultimately precipitates out after the addition of chilled ethanol.

pBR322, which is used in recombinant DNA technology, is a -

Vector

The correct answer is Option (1) → Vector 

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.

 "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.