Which enzyme is involved in proofreading during DNA replicat

Which enzyme is involved in proofreading during DNA replication? 1) 5\"to 3\"exonuclease 2) 3\"to 5\"exonuclease 3) 5\" to 3\" endonuclease 4) 3\" to 5\" endonuclease 5) DNA polymerase Which of the following would not inhibit a cell preparing to undergo mitosis? 1) chromosomal abnormalities 2) Cdc-activating kinase activity 3) Chk1 inhibition of Cdc25 4) p21 inhibition of G1 5) environmental signals that no new cells are needed

Solution

19. Proofreading activity maintains fidelity of DNA replication. proofreading is scanning of terminal nascent DNA chains for error and reparing them.

it is performed by 3\'-5\' exonuclease activity of DNA polymerase. in E.coli DNA POLYMERASE I perform it and in eukaryotes polymerase gamma, delta and epsilon do this.