MMBIO Test 3 Flashcards
(43 cards)
What kind of damage to UV-indued damage do?
thymine dimer (cyclobutane pyrimidine dimer)
What kind of damage to UV-indued damage do?
thymine dimer (cyclobutane pyrimidine dimer)
What is a common mutant of base oxidation?
8-oxoguanine
8-oxoguanine causes what kind of mutations? What new bond forms instead
Transversion. Usually G-C. 8-oxoguanine can also go with Adenine
What happens in base alkylation?
An akyl group is added (methyl/ethyl)
What are common mutations that happen in base alkylation?
o6-metylguanine… G pairs with T
o4-methylthymine.. T pairs with G
What is base deamination?
Takes off the ammine (NH2) group
What change happens with base deamination?
Cytosine is converted to uracil
What happens in base mismatches?
Nothing is chemically damaged; Polymerase error; Mismatches occur in E coli with high frequency in the pol III e subunit than normal cells
How do you repair UV damage?
CDP photolyase uses energy to fix cyclobutane rings (not found in humans or other placental animals… they would fix through base excision repair)
How can bases that have been alkylated be fixed?
DNA alkyltransferases remove alkyl groups directly. Suicide Enzymes
What proteins are involved in base excision repair?
DNA glycosylase, AP endonuclease, plymerase, ligase
What is the roll of DNA glycosylase
locates and removes the damaged base in base excision repair (different names for different types of gylcosylases)
What proteins are involved in nucleotide excision repair?
In E. Coli Uvr A,B,C,D. In humans XP
What is the process of Base Excision Repair?
DNA glycosylase find/rip out damaged base, AP endonuclease rips out the Phosphodiester bonds, Polymerase/Ligase activity
What is the process of nucleotide excision repair?
UvrA falcilitates binding to UvrB to the distorted region of DNA. UvrC makes nick on outsides of damaged strand. UvrD (helicase_ facilitates dissociations. Pol I and ligase.
What proteins are involved in mismatch repair?
Dam, MutS, MutL, MutH, UvrD, exonucleases, pol III, and ligase
Process of mismatch repair?
Dam methylates older stands. MutS recognizes, MutL assosiates and activates MutH to cut at nearby GATC site. UvrD helicases separates the non-methyl stand. Exonucleases chop up. Pol III, ligase
What happens when repair doesn’t come on time
Translesion Synthesis. Pol IV or pol V
What happens in humans when repair doesnt come on time
POLH can put two adenines accross from a thymine dimer
What is a common mutant of base oxidation?
8-oxoguanine
8-oxoguanine causes what kind of mutations? What new bond forms instead
Transversion. Usually G-C. 8-oxoguanine can also go with Adenine
What happens in base alkylation?
An akyl group is added (methyl/ethyl)
What are common mutations that happen in base alkylation?
o6-metylguanine… G pairs with T
o4-methylthymine.. T pairs with G
