DNA Repair, Recombination, and Rearrangement Flashcards
1
Q
Things that cause damage to DNA
A
- ionizing (x/gamma rays) and UV radiation
- methylating reagants such as MNNG
- cross-linking reagents such as the anticancer drug cisplatin
- bulky hydrocarbons such as bento-a-pyrene (carcinogen from tobacco smoke)
2
Q
DNA repair mechanisms
A
- photoeactivation
- removal of alkyl guanines
- nucleotide excision repair
- base excision repair
- mismatch repair
- double-strand break repair
- daughter strand gap repair
3
Q
mutation
A
any heritable (permanent) change in the structure of an organism’s DNA or chromsomes
4
Q
loss of function mutations
A
- gene product has less or no function
- phenotypes are most often recessive
- exception: haploinsufficiency
5
Q
null allele
A
- allele that has a complete loss of function
- amorphic mutation
6
Q
haploinsufficiency
A
when the reduced dosage of a normal gene product isn’t enough for a normal phenotype
7
Q
gain of function mutation
A
- change the gene product such that it gains a new and abnormal function
- usually have dominant phenotypes
- aka neomorphic mutation
8
Q
dominant negative mutation
A
- aka antimorphic mutation
- have an altered gene product that acts antagonistically to the normal allele
- usually result in altered molecular function (often inactive)
- characterized bu a dominant or semi-dominant phenotype
9
Q
lethal mutation
A
- lead to a phenotype incapable of effective reproduction
- leads to death
10
Q
whole chromosome or genome level mutation
A
- fragment deletions/insertions (gene aberrations)
- inversions
- ploidy changes
11
Q
molecular or base-pair level mutation
A
- deletions
- insertions
- substitutions (point mutations)
12
Q
origins of mutations
A
- errors during DNA replication
- errors in chromosome alignments & separation during mitosis and meiosis
- spontaneous chemical changes in base structure
- induced chemical changes in base structure
13
Q
polymerase I & III function
A
- exonuclease proof-reading
- corrects mistakes
14
Q
tautomeric shifts
A
- spontaneous mutations
- the spontaneous isomerization of a nitrogenous base to/from keno and enroll forms or to/from amino and amino forms
- cause transition mutations
- replacement occurs in second generation of replication
15
Q
transition mutation
A
one purine/pyrimidine base pair is replaced with the other purine/pyrimidine base pair
16
Q
transversion mutation
A
replacement of a purine//pyrimidine with a pyrimidine/purine pair
