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14 Cards in this Set
- Front
- Back
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Endogenous origins of DSBs?
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oxidative damage- reactive oxygen species -replication fork stalling |
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How does oxidative damage occur? |
-formed naturally during metabolism of oxygen -secreted by cells of immune system -superoxide reacts with and damages all molecules it comes in contact with |
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How do exogenous agents cause DSBs? |
ionizing radiations such as X-rays, Gamma rays -radiomimetic drugs used during chemo 65% of damage caused by x and gamma rays are due to indirect effects |
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T or F exogenous damage that causes DSB are indirect oxidative damage |
true.... high energy can penetrate deeper into the tissue and can ionize tissues on the way... they generate more oxidative species |
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What is an effect of the replication fork stalling? |
Double stranded break |
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Consequences of unrepaired DSBs |
fragments one or both chromosomes if theres a nick in the parental DNA |
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What are the 2 pathways for DSB repair? |
Homologous recombination and NHEJ (Non homologous end joining |
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Which is the main pathway for DSB during replication? |
Homologous recombination |
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What phase does Homologous recombination occur during? |
Last S-phase and G2 |
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What phase does NHEJ occur during? |
Go and G1 (when cells have not yet duplicated their DNA |
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What form of DSB repair is a major pathway in multicellular eukaryotes? |
NHEJ |
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T or F Homologous recombination is a main pathway in eukaryotes |
False... it is the main pathway in bacteria |
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Name the steps to NHEJ |
resection to expose ssDNA ---> alignment of region at microhomology ---> trimming of overhangs ---> ligation |
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T or F NHEJ results in loss of sequence |
True... its mutagenic as well, error prone repair |
