BIO 3170 Midterm: LO DNA repair
25 Feb 2017
School
Department
Course
Professor
LO: DNA Repair
1. Compare the DNA mutations induced by environmental factors including: chemicals, radiation
and water
• Usually the mutations induced by environmental factors are post replication
o Meaning that the error is introducd after DNA polymerase copies DNA
o DNA polymerase through proof reading will detect mismatched DNA that do not
respect Watson crickbinding
o Through exonucleaseactivity the wrongly nucleotide will be removed
Chemical modification:
• Alkylation of Guagnin nucleotide
• There are multiple positions where alkylations can occur which will determine the hydrogen
bond capacity
Methylated C residue
• O is added
Radiation
• T dimers which occur on the same DNa strand on consecutive T residues
find more resources at oneclass.com
find more resources at oneclass.com
Deamination and Depurination created by water
• C→ U is a deamination and replaced with keto group
• C methyl and the aminogroup is replaced with keto grop
• Thisaffects the binding f proteins with DNA and the pairing
Durpurination
• The base is lost but the sugar remainsin the DNa strand
• and the system will regenerate and replaceit
2. How do tautomeric forms of the bases cause mutations in DNA?
Tautomeric forms are chemical strucutures that nucleotides can adopt and they are rare and
induced by water
3. Briefly Describe 3 main mechanisms of DNa repair.
Replication Errors – Mismatch repair system
• Series of Mut Family for recognition of where the mismatch is
• Exonuclease and DNA helicase will undo itself
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Chemical modification: alkylation of guagnin nucleotide, there are multiple positions where alkylations can occur which will determine the hydrogen bond capacity. Radiation: t dimers which occur on the same dna strand on consecutive t residues. Deamination and depurination created by water: c u is a deamination and replaced with keto group, c methyl and the aminogroup is replaced with keto grop, thisaffects the binding f proteins with dna and the pairing. Tautomeric forms are chemical strucutures that nucleotides can adopt and they are rare and induced by water: briefly describe 3 main mechanisms of dna repair. Replication errors mismatch repair system: series of mut family for recognition of where the mismatch is, exonuclease and dna helicase will undo itself, ssb, dna polymerase and resynthesis and insert propermismatch. Dna damage: chemcial modification, base exicision repair ony the base is removed, the sugar remains in the phosphodiester bonds and the chain isnot broken, dnapol 1 and dna igase.
