BIOL 205 Lecture Notes - Lecture 9: Pyrimidine Dimer, Dna Replication, Ultraviolet
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slides #6 from week 8!
ben johnson !
if you could have a mutation that could increase muscle mass!•
eero marityranta - blood doping - 15% more RBC could carry 15% more oxygen!•
single point mutation in erythropoetin receptor !◦
trinucleotide repeats within a coding region !
huntington - CAG repeat!•
slow and progressive disease, correlated to expansion of repeats!◦
replication repair system is not taking care of repeats !‣
apoptosis is programmed cell death !•
mutant protein that precipitates, binds to transcription factors, reduces RNA made!◦
large polyglutamine binds to itself and stuﬀ its not supposed to bind to !‣
slide set # 7!
fragile x !
occurs in noncoding region, associated with autism !•
trinucleotide CGC expands in non coding!◦
causes fragile because two chromosomes come together in metaphase, one arm expands one doesnt. ‣
they don't bind together bc arms are
shortened they break!
FMR-1 hinders transcription CGC repeat is •
upstream of ATG!
permutation - 6-59 60-200 unstable bc ◦
prone to further expansion no methylation
full mutation shuts down mutation because ◦
of hypermethylation of DNA !
no transcription, unstable!‣
mechanism behind expansion!•
slipped mispairing , DNA repair has broken ◦
down and doesn't identify bubbling !
tsutomu yamaguchi !•
lived through two nuclear blasts !◦
why was his DNA repair so robust!◦
his daughters died very young !‣
gamma radiation chromosomes are broken into many pieces and DNA replication ﬁxes it!◦
molecular basis of induced mutation!•
incorporation of base analogs!◦
cancer cells replicate faster than normal cells, inject person with base analogs bc cancer cells take them ‣
up faster incorporate into DNA, cell death!
bromine replaces methyl and causes mispairing causes transition mutation !•
intercalating agents are very ﬂat!◦
slip in cause insertion or deletion of single ‣
nucleotide pair which causes a frame shift!
aﬂatoxin - deadly toxin aspergillus!◦
died from anemia caused by radiation that damaged ◦
her bone marrow cells!
free radicals, hydrogen peroxide, super oxide radicals!•
causes base deletions, single nicks in DNA strands, ◦
cross linking, chromosomal breaks!
uv light, less energy causes thymine dimers and 6-4 ◦
photoproducts (btwn two pyrimidines) !
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