Question

Researchers found a strain of E. coli bacteria that had mutation rates one hundred times higher
than normal.Which of the following statements correctly describes it the best

A. The proofreading mechanism of DNA polymerase was not working properly.
B. The DNA polymerase was unable to add bases to the 3′ end of the growing nucleic acid chain.
C. The single-strand binding proteins were malfunctioning during DNA replication.
D. There were one or more base pair mismatches in the RNA primer

Answer 1

Answer: A - The proofreading mechanism of DNA polymerase was not working properly.

Explanation: Due to the proofreading mechanism of DNA polymerase not working properly, researchers would have found a strain of E. coli bacteria that had mutation rates one hundred times higher than normal.

DNA polymerases have the ability to proof read, using 3' → 5' exonuclease activity. Most of the mistakes during DNA replication are promptly corrected by DNA polymerase by proofreading the base that has been just added. But, some replication errors make it past these mechanisms, thus becoming permanent mutations