Class Notes (1,100,000)
CA (620,000)
McGill (30,000)
BIOL (600)
BIOL 202 (200)
Lecture 27

BIOL 202 Lecture Notes - Lecture 27: Dna Repair, Transposable Element, Rad51


Department
Biology (Sci)
Course Code
BIOL 202
Professor
David Hipfner
Lecture
27

This preview shows pages 1-3. to view the full 30 pages of the document.
Overview of DNA repair systems
Hipfner Biol 202 1
Pierce. Genetics: A Conceptual Approach, Fourth Ed.
Translesion
DNA synthesis
Pyrimidine dimers, large adducts,
apurinic sites
Homology-dependent
repair systems
Error-prone
repair systems

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Hipfner Biol 202 2
Homologous double
strand break repair
oSynthesis-dependent strand
annealing… in cells that have
already replicated DNA
End-trimming of double-stranded
breaks
Rad51 binds single-stranded ends
& Rad51-DNA filament mediates
search for sister chromatid &
“strand invasion”
Sister chromatid used as template
to synthesize missing DNA
Ligase seals nicks
Fig 16-27
Similar mechanism mediates
meiotic recombination
Rad51 Rad51

Only pages 1-3 are available for preview. Some parts have been intentionally blurred.

Hipfner Biol 202 3
Error-prone mechanisms – SOS/
translesion repair
oBulky additions &/or pyrimidine dimers can lead
to stalling of DNA polymerase & cell death
In order to let replication continue, an error-prone
DNA “repair” system is activated that puts random
nucleotides opposite the lesion
Activation of “bypass polymerases
Larger active site pocket, can accommodate DNA adducts
No 3´-5´ proofreading activity – allowed to make mistakes
Only adds a few nucleotides before falling off DNA
Leads to mutation itself
(details – Fig 16-24/25)
You're Reading a Preview

Unlock to view full version