Question

It is possible to mutate E. coli DNA Pol I so that it no longer has any exonuclease activity. What would be a potential result of this change? Select one:

a. The enzyme would be more error prone
b. The enzyme would become more processive and more error-prone.
c. The enzyme would become more processive.
d. None of these is a potential outcome.
e. The enzyme would become more efficient in base excision repair

Answer 1

The mutation leading to E. coli DNA Pol I lacking exonuclease activity would make the enzyme more error-prone, as it would lose the ability to correct mistakes during DNA synthesis. option a is correct.

Step-by-step explanation:

If E. coli DNA Pol I no longer has any exonuclease activity due to a mutation, the potential result of this change would be that the enzyme would become more error-prone. DNA polymerase has two main functions during DNA replication: polymerization of nucleotides to form a DNA strand and proofreading through its exonuclease activity. The exonuclease function allows for the removal of incorrectly incorporated bases immediately after they are added, which is an essential part of the enzyme's proofreading capability.

Without this exonuclease activity, DNA Pol I would be unable to correct mistakes made during DNA synthesis, leading to an increased likelihood of mutations in the newly synthesized DNA strand. These mutations could be point mutations (like substitutions, insertions, or deletions) and could potentially lead to serious complications such as malfunctions in protein synthesis or even diseases like cancer if the mutations affect crucial genes.

Therefore, the correct answer to the question is option a: The enzyme would be more error prone. An enzyme without exonuclease activity loses its ability to perform an essential proofreading function, resulting in a higher rate of errors during DNA replication.