DNA Repair 2-28

Question 1

How can mutations alter proteins

Answer 1

change in functional amino acids (affecting enzymatic activity), mutation changes the splice pattern of the mRNA

Question 2

Four mutagenic agents

Answer 2

alkylating agents, nitrates/nitrites, base analogs, intercalating agents

Question 3

Two means of mutating without chemical agents

Answer 3

Polymerase mistakes during replication, radiation damage

Question 4

what base does 5-MeCytosine get substituted for when it gets deaminated?

Answer 4

thymine

Question 5

What happens when radiation create thymine dimers?

Answer 5

It keeps polymerase from replicating that region

Question 6

benzopyrene

Answer 6

intercalating agent in cigarettes

Question 7

mustard gas

Answer 7

alkylating agent

Question 8

3 types of DNA repair

Answer 8

direct, excision, mismatch

Question 9

Directly repaired lesions

Answer 9

alkylated bases, thymine dimers

Question 10

Why is direct repair of DNA relatively safe?

Answer 10

no cleaving the backbone, base removal

Question 11

WHat lesions are repaired by excision repair

Answer 11

n-thymine dimers, deaminated bases

Question 12

By what mechanism will transcribed regions of the DNA have different rate of mutagenesis than non-transcribed regions

Answer 12

RNA Polymerase subunit TFIIH repairs transcribed regions

Question 13

It which cases would a chemical mutagen maybe cause mutation, but perhaps not

Answer 13

If cytosine is already methylated before mutagenesis with deaminating agents, then it will become a thymidine (Mutagenesis), if it was not methylated, it will become an easily repaired uracil (No Mutagenesis)

Question 14

3 diseases caused by faulty DNA repair

Answer 14

Xeroderma Pigmentosum (XP), Hereditary Non-polyposis Colon Cancer (HNPCC), Fanconi Anemia

Question 15

2 characteristics of Fanconi Anemia

Answer 15

growth retardation, abnormal development, stem cell failure, chr fusion after exposure to cross-linking agents, can be caused by 12 different genes

Question 16

2 characteristics of XP

Answer 16

mutation in the excision repair genes, freckling, photosensitivity, cataracts, skin tumors

Question 17

2 characteristics of HNPCC

Answer 17

Mismatch repair mutation causing slippage during replication, microsatellite instability in VTRs

Question 18

What 2 proteins usually cause HPCC?

Answer 18

MTH1 (MutL), MTH2 (MutS ortholog)

Question 19

2 interventions for DNA repair diseases

Answer 19

reduce mutagen exposure, possibly insertion of replacement genes

Question 20

UvrA, B, C proteins

Answer 20

excision repair proteins

Question 21

MutL, MutS

Answer 21

mismatch repair proteins in prokaryotes