Part C: Lecture 9 Flashcards
Mutation is both ______in the DNA and the
process by which _____
-a heritable change (outcome)
-such a change occurs (event)
Mutant (def.)
a cell/organism carrying a mutation
Two types of mutations
-spontaneous
-induced
Spontaneous mutations are ____
accidental
Induced mutations are due to _____
external factor
Mutagen (def.)
a physical or chemical agent that raises the frequency of mutation above the spontaneous rate
Even without mutagens, a certain number of ____ will still occur
mutations
DNA lesion is ____
physical damage to DNA
3 results of DNA lesions
-kills cells
-repaired correctly
-repaired wrong
Process of mutation
1) DNA lesion
2) no/incorrect repair
Deamination of cytosine is a ____
spontaneous reaction that turns cytosine -> uracil
Deamination of cytosine process
cytosine + H20 -> NH3 + uracil
(lose amine group, replace with O from H2O)
How common is deamination of cytosine
100 bases/cell/day
Immediate result of deamination of cytosine
GC -> GU
Overall result of deamination of cytosine PROCESS
GC –> GU –> (after dna rep.) GC + AU –> (after dna rep.) AT + AU
Overall result of deamination of cytosine (GC bp ->
AT bp
GC -> AT is the same as saying ____
CG -> TA
Base excision repair (BER) steps
1) DNA repair enzymes recognize defective bases and remove them
2)Other DNA repair enzymes fix AP site
DNA repair enzymes fix ___ not ____
lesions not mutations
Uracil DNA Glycosylase recognizes ___
uracil in DNA molecule for removal
AP sites are ___
places in DNA missing a base
Two types of AP sites
apurinic sites
apyrimidinic sites
apurinic sites are missing ___
A or G
apyrimidinic sites are missing ___
C or T
BER of deamination of cytosine
1) removal of uracil base by uracil DNA glycosylase (creates AP site)
2) DNA repair enzymes remove the sugar+ phosphate backbone
3) dCTP + DNA Pol, DNA ligase repair space in DNA
Prompt repair of lesion will ____
stop mutation from occurring
Repairing DNA right after deamination of cytosine result
GC –> GU -> GC
Delayed repair of lesion will cause ___
a mutation
Repair of DNA right after DNA replication after deamination of cytosine
GC –> GU –> AT
Repeats are ___ in chromosomes
common
In human chromosomes, we have a lot of ___ repeats
CACA
DNA pol falls off a repeat and the strands reanneal incorrectly so when____
DNA Pol returns. one strand will have more nucleotides
If the new strand loops out, you get___
insertion of base pair(s)
If template strand loops out, you get ____
deletion of base pair(s)
how many types of base pair substitutions?
6
types of base pair substitutions: GC ->
AT or TA or CG
types of base pair substitutions: AT ->
GC or CG or TA
Indels are the ____
insertions or deletions of 1 or more bp
Properties of spont. mutations: Genes are more likely to mutate if they are ____
-are larger
-contain repeats
