DNA Repair

Question 1

what are the 3 systems for if mistakes occur during replicating

Answer 1

1. Mismatch repair
2. Excision repair
3. Double-strand break repair

Question 2

when does SOS repair occur

Answer 2

when there is a lot of ssDNA at replication forks and DNA polymerase is blocked

Question 3

what happens if the systems don’t work

Answer 3

stop replicating

Question 4

what occurs in DNA repair

Answer 4

1. recognition and removal of damaged DNA
2. filling in of missing DNA by DNA polymerase
3. ligation of the newly-made DNA to the existing DNA

Question 5

What is mismatch repair

Answer 5

when a long DNA section is removed and resynthesises by proof-reading polymerase. Any distortion is recognised by mismatch repair proteins

Question 6

what is nucleotide excision repair

Answer 6

when a damaged nucleotide is recognised by different set of proteins. The base is removed, producing a small gap, which is filled

Question 7

what are some repair figures

Answer 7

1 error per 107 nucleotides (without repair)
1 error per 109 nucleotides ( with repair)

Question 8

what do mutations cause

Answer 8

inherited disease or cancer

Question 9

what is MMR

Answer 9

Mismatch repair- removes long patches of DNA with Mut proteins

Question 10

what is NER

Answer 10

Nucleotide Excision Repair- single nucleotide removed

Question 11

what is BER

Answer 11

Base Excision Repair- a base moiety part is removed

Question 12

what are medical examples of mutations

Answer 12

Xeroderma Pigmentosum (multiple skin cancer) and hereditary nonpolyposis colon cancer (HPNCC)