Question

pBR322 is a __________________
A. Restriction enzyme
B. Plasmid
C. Polymerase
D. Ligase

Answer 1

Hint: In the process of recombinant DNA technology, small pieces of DNA are inserted and maintained inside an organism and administered the foreign piece is further used for cloning purposes. The transfer of the foreign material requires some type of delivery system that efficiently delivers the desired DNA. These delivery systems are known as cloning vectors.

Complete answer:
A cloning vector is defined as a small fragment of DNA that is stably maintained in an organism. The cloning vectors are important in the process of DNA recombinant technology. Inside the cloning vectors, the foreign fragments of DNA are inserted for the process of cloning. There are different types of cloning vectors used and among which the most commonly used vectors are the plasmids or the plasmid vectors.
pBR322 is a type of artificial plasmid and is one of the most commonly used cloning vectors. It is generally used as cloning vectors in E.coli. It was created by Herbert Boyer at the University of California.
The pBR322 contains about 4361 base pairs and it has two antibiotic resistance genes which is the gene bla and gene tetA. The gene bla encodes for the ampicillin resistance proteins (AmpR) while the other gene encodes for tetracycline resistance (TetR) protein. In addition to this, it also contains the origin of replication, rop gene and other unique restriction sites.
Restriction enzymes are varieties of proteins that help to identify short, specific nucleotide sequences and make cuts on the DNA at specific sites. The sites at which the restriction enzymes cut the DNA are known as restriction sites or target sites.
Polymerase enzymes are the enzymes that are responsible for synthesis of long chains of polymers or nucleic acids. They help to copy DNA template strands by using base pair interactions.
The ligase catalyzes to join the two large molecules by formation of new chemical bonds. The ligases are used to connect the two strands of DNA together by forming bonds between the phosphate group of one strand and the deoxyribose group of another.
Thus, the right option is B.

Note: Several types of cloning vectors are used that carry small fragments of desired DNA and are cloned to host organisms. Pbr322 is used as a cloning vector in E. coli and it is a plasmid. It contains the origin of a replication site, two antibiotic resistant genes and restriction sites.