Question

The enzyme DNA polymerase in E.coli is a DNA dependent polymerase and also has the ability to proof-read the DNA strand being synthesised. Explain. Discuss the dual polymerase.

Answer 1

Dual polymerase:

Enzyme activities of DNA dependent DNA polymerase (dual polymerase):

• The DNA dependent DNA polymerases have both exonuclease and polymerase activity.
• The polymerase has proofreading activity in 3’ to 5’ direction and removes the mismatched nucleotides with exonuclease activity. It has the ability to repair the damage caused to DNA by UV rays.
• The DNA dependent polymerase adds nucleotides complementary to the template DNA in the new strand with its $3^{\prime }\to 5^{\prime }$ polymerase activity.