DNA repair Flashcards
DNA damage may be caused by:
- radiation
- environmental conditions
- Endogenous reactive oxygen species
A _____ is any heritable (permanent) change in the structure of an organism’s DNA or chromosomes.
- mutation
______ is the result of gene product having less or no function. When the allele has a complete loss of function it is often called a ___ allele (_____ mutation).
- loss of function
- null
- amorphic
_______ is a change the gene product such that it gains a new and abnormal function. Sometimes called a ______
- gain of function
- neomorphic
_______ have an altered gene product that acts antagonistically to the normal allele.
- dominant negative, antimorphic mutations
____ are mutations that lead to a phenotype incapable of effective reproduction (e.g., death).
- lethal
Mutations that affect the whole chromosome or genome level include
- Fragment Deletions/Insertions (gene abberations)
- Inversions
- Ploidy changes
Mutations that affect the molecular or base pair level include
- deletions
- insertions
- substitutions
Molecular mutations are also known as ______
- point mutations
Origins of mutations
- Erors during DNA replication.
- Errors in chromosome alignments & separation during mitosis & meoisis.
- Spontaneous chemical changes in base structure.
- Induced chemical changes in base structure
_____ cause “transition mutations” where one purine/pyrimidine base pair is replaced with the other purine/pyrimidine base pair (AT with GC)
- tautomeric shifts
ex: AT with GC
A ______ is the replacement of a purine/pyrimidine with a pyrimidine/purine pair
- Transversion
ex: AC with TG
______ use light energy to break the bonds linking pyrimidine rings
- photolyases
In nucleotide excision repair _____, _____ and _____ complete the repair process
- helicase, polymerase and ligase
In methyl-directed mismatch repair ______ and ____ complete the repair
- DNA polymerase 3 and ligase
________ repair and ________ is through homolougous recombination
- Double strand break
- holliday model
In _________ the replicated portion of an incompletely replicated chromosome is used as a repair template
- daughter-strand gap repair
_________ establishes lysogeny in bacteriophage λ
- Site-specific recombination
_____ uses ATP to promote the pairing of homologous DNA sequences
- RECA
A _______ is a bacterial transposable element flanked by short repeated sequences
- transposon
Gene amplification may occur via unequal _______ (unequal crossover)
- sister-chromatid exchange
Single stranded break, thymine dimer, base mismatch and base alkylation can all lead to DNA _____ that can cause ____
- damage
- cancer
UV radiation, alkylating agents, bulky hydrocarbons and DNA crosslinking agents can lead to ________
- DNA damage
