Question

Identify the plasmid:

• A. All of the above
• B. $Hind$ III
• C. $Eco$RI
• D. pBR $322$

Answer 1

The correct option is D pBR $322$

Plasmid
Plasmids are circular, extranuclear, double stranded, self replicating DNA molecules that are used as vectors for small fragments of DNA in the gene cloning process.

pBR$322$
pBR$322$ is a plasmid and it is one of the first widely used Escherichia coli cloning vectors. It is named after Bolivar and Rodriguez.

Restriction endonuclease
Restriction endonucleases are enzymes which cleave the DNA by digesting phosphodiester bonds at specific sequences (recognition sequence) within the DNA. They help in cutting the vector and the DNA of interest to form rDNA. Examples include $Hind$ III, $Eco$R I etc.

$Eco$ RI
$Eco$R I is the restriction endonuclease from Escherichia coli that has 5’- GAATTC -3’ as its recognition sequence.

$Hind$ III
$Hind$ III is the restriction endonuclease from Haemophilus influenzae with the recognition sequence $5$’ - AAGCTT - $3$’.

Final answer:
b. pBR $322$