Question

Chemical knives or molecular scissors of DNA are

• A. ligases
• B. polymerases
• C. restriction endonucleases
• D. transcriptases

Answer 1

The correct option is C restriction endonucleases

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

The cutting of DNA provides space for the insertion of foreign DNA into the vector DNA to form rDNA. Since the DNA molecule is cut by these restriction enzymes they are also called molecular scissors or chemical knives.

Polymerase enzymes allow the formation of a long chain of nucleic acids using nucleotides by creating phosphodiester bonds. These enzymes help in the replication or synthesis of nucleic acids. Examples include DNA polymerases and RNA polymerases.

Ligase enzymes catalyze the formation of phosphodiester bonds, thus joining the desired DNA fragments. In genetic engineering it helps in joining the vector DNA with the DNA of interest to form the rDNA.

Transcriptase is an enzyme that catalyzes the formation of RNA from DNA molecules in transcription.

Hence the correct option is
a. restriction endonucleases