Chapter 13.4 (Exam 3) DNA Repairs

Question 1

What can be the causes of errors in DNA?

Answer 1

DNA polymerases make mistakes and DNA can be damaged by chemicals, UV radiation, and other threats

Question 2

What are the three repair mechanisms that cells use to repair errors in DNA?

Answer 2

Proofreading

Mismatch repair

Excision repair

Question 3

What is proofreading?

Answer 3

DNA polymerase recognizes mismatched pairs and removes incorrectly paired bases as the DNA is being replicated

Catches 99% or more mismatches

Question 4

What is mismatch repair?

Answer 4

Newly replicated DNA is scanned for mistakes by other proteins and mismatches can be corrected

Question 5

What is excision repair?

Answer 5

Enzymes scan DNA for damaged bases—they are excised and DNA polymerase I adds the correct ones