The enzyme DNA polymerase in E.coli is a DNA-dependent polymerase and also has the ability to proofread the DNA strand being synthesised. Explain. Discuss the dual polymerase.
In bacteria, three types of DNA polymerases are three. All of them can add nucleotides in 5'→3' direction. The process exonuclease activity as well. DNA polymerase lll can proofread the newly synthesized strand and senses the wrong base insertions.
It deletes the wrong bases and helps correct the mistake by putting in the right one, DNA polymerase. The only mistake it cannot corrects the substitution of uracil in place of thymine.
It can repair any damages done to DNA by UV exposure, etc., or the leftover proofreading mistakes. It detects mutation caused by UV, removes mismatched pairs, and puts back the right ones.
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