DNA Damage/Repair

Question 1

mutations: definition

Answer 1

permanent changes in the sequence of bases (genetic information)

Question 2

4 consequences of mutations

Answer 2

changed amino acid sequence = change in function of cellular protein. cell death/apoptosis. failure of embryonic development. cancer

Question 3

replication is carried out by? fidelity?

Answer 3

DNA polymerases: very high fidelity but not perfect

Question 4

error rate of DNA polymerase

Answer 4

1 mistake per million to 100 million nucleotides

Question 5

spontaneous depurination

Answer 5

purines = A or G, hydrolysis of bond joining base to sugar ring

Question 6

cancer: mutation in what gene?

Answer 6

mutation that alters the function of a proto-oncogene

Question 7

oncogenes code proteins with a role in? (2)

Answer 7

apoptosis aka natural ell death pathway. regulation of cell cycle or growth pathways

Question 8

how does a proto oncogene become an oncogene?

Answer 8

direct mutation that affects protein function. mutation that causes increased stability of mRNA for a protein or gene duplication = protein over expression. chromosomal translocation that increases expression of a protein

Question 9

3 types of repair mechanisms

Answer 9

mismatch repair. base excision repair. nucleotides excision repaire

Question 10

what does mismatch repair do

Answer 10

repairs mismatches in replicated DNA not caught in proof reading

Question 11

base excision repair

Answer 11

repairs abnormal bases

Question 12

nucleotide excision repair

Answer 12

repairs pyrimidine dimers, like thymine dimers from UV radiation

Question 13

xeroderma pigmentosum

Answer 13

heriditary defect of DNA repair enzymes = extreme sensitivity to sunlight