Question

Restriction endonucleases used widely in RDT are obtained from

• A. All prokaryotic cells
• B. Bacteriophages
• C. Bacterial cells
• D. Plasmids

Answer 1

The correct option is C Bacterial cells

Definition of restriction endonuclease
Restriction endonucleases are the enzymes which cleave the DNA by digesting phosphodiester bonds at the specific sequences within the DNA. Examples include EcoR I.

Source of restriction enzymes
Restriction enzymes naturally exist in bacteria and are used as defense mechanisms against bacteriophages. More than 900 restriction enzymes which have unique recognition sites have been isolated from more than 230 strains of bacteria.

Plasmid
Plasmids are extranuclear, circular, double stranded DNA. They are usually used as vectors in genetic engineering.

Bacteriophages
Bacteriophages are viruses that infect bacteria.

Prokaryotes
Prokaryotes are single celled organisms which lack a nucleus and specialized cell organelles. It includes bacteria, archaea, and cyanobacteria. Not all prokaryotes show a suitable restriction enzymes in them.

Final answer
(B) Bacterial cells