Topic 5-3

Question 1

what is a mismatch repair

Answer 1

occurs shortly after DNA, where enzymes cut out the newly synthesized strand of DNA and replace it with new nucleotides

Question 2

what is a direct repair?

Answer 2

restores thw correct chemical strucutres of altered nucleotides

Question 3

what is a base excision repair?

Answer 3

glycosylase enzymes recognize and remove specific types of damaged bases. the entire nucleotide is then removed, and a section of the polynucleotide strand is replaced

Question 4

what is a nucleotide excision repair?

Answer 4

removes and replaces many types of damaged DNA that distorts the DNA strucutre by separating the two DNA strands, removing the distorted DNA, DNA polymerase filling in the gap, and DNA ligase sealing the gap

Question 5

what are the two types of double stranded break repair

Answer 5

homology directed repair, nonhomologous end joining

Question 6

• same mechanism as homologous recombination
• usually uses sister chromatid to repair break
• BRCA1 and BRCA2 are enzymes involved in this process
  these are chracteristics of:

Answer 6

homology directed repair

Question 7

• no ‘template’ used, thus is error prone
• usually occurs in G1 cell cycle stage
• proteins recognize broken ends of DNA and join them together
  these are characteristics of:

Answer 7

nonhomologous end joining

Question 8

a disease chracterized by freckle-like spots on the skin and a predisposition to skin cancer

Answer 8

xeroderma pigmentosum