DNA repair Flashcards
types of mutations
silent mutation missense nonsense substitution frameshift supressor spontaneous
Spontaneous mutation
deamination, oxo–>enol
deprivation
supressor mutation
Cover up anothher mutation
Frameshift mutation
sNTP is inserted or deleated, tay sachs
nonsense
premature termination
missense
diff a.a incorporated into protein molecule and may or may not depending on lovation
silent mutation
no detectable effect due to degeneracy
ames test
The Ames test is a method for screening potential mutagens. The test uses( strains that have lost the ability to synthesize a needed substance of )Salmonella typhimurium that carry mutant genes, making them unable to synthesize histidine
Types of DNA repair systems
Mismatch repair (MMR) • Base-excision repair (BER) • Nucleotide-excision repair (NER) • Nonhomologous end-joining (NHEJ) • Homologous recombination (HR)
DNA damage:
Reaction with carcinogen: bulky group addition
Base alkylation (Methylation)
(spontaneous, polycyclic aromatic hydrocarbons)
repair double strand breaks
HR
NHEJ
The effects of mutations on (protein) function
• No effect
• Lethal mutation
• Loss-of-function mutation:
• Gain-of-function mutation: new or enhanced activity
• Dominant negative mutation: the gene product
interfere with the function of the normal gene
product in heterozygotes.
• Back mutation or reversion
DNA glycosylase
removes accidentally deaminated cytosine in DNA
homologus end joining
Using the second , undamaged chromosome as atemplate for transfering info to the broken chromosome.
Non-homologus end joining
mutations can occur when fixing. The ends are joined together without replacing the ends cut out by wndonuclease
