Genetics Quiz 1 Dna Mutation & Repair

Front 1

Mutation/damage when...

Back 1

Results in permanent mutation/damage ONLY when it is passed-on to progeny.

Front 2

Spontaneous mutations

Back 2

1. replication errors
2. changes to bases: deamination
3. loss of bases from nucleotides: produces "gaps" in template

Front 3

Chemically-induced mutations

Back 3

1. oxidative damage
2. alkylation
3. nucleotide/nucleoside analogs
4. intercalating dyes

Front 4

Addition of hydroxyl groups

Back 4

oxidative damage

Front 5

Nucleotide/nucleoside analogs

Back 5

results in mispairing which causes mutations which result in death of cancer cell

Front 6

Inserts itself between basepairs causing a frame-shift mutation

Back 6

intercalating dye

Front 7

Radiation damage to DNA causes

Back 7

1. UV irradiation (forms Pyrimidine dimers & 6-4 photoproducts)

2. Ionizing radiation (causes dsDNA & backbones to break-->tries to put chromosomes back together but in wrong order: chromosome translocation)

Front 8

In what cell cycle checkpoint does the cell stop to access DNA damage?

Back 8

G1

Arrested if damage

Front 9

Cellular response to DNA damgae

Back 9

1. Cell cycle control
a. G1 arrest
b. programmed cell death

2. Bypass strategy/trans-lesion synthesis: in S-phase, if damage occurs, DNA pol. puts any nt and keeps going

3. Repair mechanisms

Front 10

DNA direct repair mechanisms

Back 10

1. dealkylation
2. photoreactivation of pyrimidine dimers

Front 11

DNA base-excision repair (repairs single bases)

Back 11

1. N-glycosylase: damaged base removed by cleaving N-glycosidic bond, backbone still intact

2. AP endonuclease: clip middle of DNA, backbone cleaved, and DNA pol & ligase fixes gap

Front 12

Nucleotide excision repair (repairs larger regions)

Back 12

Endonuclease clips damaged area-->now have free ends-->exonuclease removes DNA-->DNA pol & ligase fix gap

Front 13

Disease associated with Nucleotide excision repair?

Back 13

Xeroderma Pigmentosum: patients cannot do nucleotide excision repair-->very sensitive to UV light

Front 14

How does the system know which strand to fix?

Back 14

The parent strand is always correct and therefore methylated in various locations.

Front 15

Hereditary Nonpolyposis Colorectal Cancer (HNPCC)

Back 15

Genetic defect in the mismatch repair mechanism

Front 16

How do we fix double stranded break repair?

Back 16

1. Non-homologous end joining but results in replication errors & mutagenic

2. Recombination Repairs between homologous chromosomes during meiosis-cross-over event

Front 17

Cross-over Event

Back 17

-one DNA strand from broken daughter chromosome will "snatch" a piece from the other strand

DNA pol will fix the "gap."

Front 18

What, if damaged, could increase the chance of breast cancer development by 80%?

Back 18

BRCA1, BRCA2