DNA Damage, Repair, and Mutagenesis Flashcards
Locus
A segment of DNA occupying a particular position or location on a chromosome
Alleles
Alternative versions of the DNA sequence at a locus
Wild-type
An allele present in more than half of the individuals in a population
Varient (or mutant)
An allele that differs from the wild-type allele because of the presence of a mutation
Mutation
Permanent change in the nucleotide sequence or arrangement of DNA
Polymorphism
The occurrence of two or more alternative alleles at a locus, each at a frequency greater than 1% within a population
Rare Variant
Variant allele that occurs within a population at a frequency <1%
SNPs
Single Nucleotide Polymorphism
Chromosome Mutation
Mutations that leave chromosomes intact but change the number of chromosomes in a cell
Regional or Subchromosomal Mutation
Mutation that changes only a portion of a chromosome and might involve a change in the copy number of a subchromosomal segment or a structural rearrangement involving parts of one or more chromosomes
Gene Mutation
Alterations in the sequence of DNA, involving the substitution, deletion, or insertion of DNA (single nucleotide up to 100 kilobases)
Transition Mutation
Changes one purine for a different purine or a pyrimidine for a different pyrimidine
Transversion Mutation
Changes a purine to a pyrimidine or vise versa
Missense Mutation
A point mutation that alters the coding strand of the gene to specify a different amino acid
Nonsense Mutation
A point mutation in a DNA sequence that causes the normal codon for an amino acid to be replaced with a termination (“stop”) codon
RNA Splicing Mutation
A point mutation that interferes with the normal process of mRNA splicing
Can interfere with or abolish normal splicing or create alternative splicing sites that compete with normal sites during RNA processing
Frameshift Mutation
An insertion/deletion within the coding sequence of a number of bases that is NOT a multiple of 3
From the point of the insertion or deletion, a different sequence of codons is generated that encodes incorrect amino acids and can insert a premature stop codon.
Codon Insertin/Deletion
An insertion/deletion of a number of bases that IS a multiple of 3
Simple insertion or deletion of the corresponding amino acids; effects on protein product can be highly variable
Larger duplications, deletions, and inversions
Duplications/deletions/inversions of a larger segment of a single chromosome are usually the result of homologous recombination between DNA segments with high sequence homology
Insertion of Repeat Elements
Insertion of repeat elements within the coding sequence interrupts and destroys information leading to gene product
Haploinsufficiency
Inability of a single copy of the genetic material to carry out the functions normally performed by two copies
Dominant Negative
A disease-causing allele that disrupts the function of a wild-type allele in the same cell
Exogenous
External factors
Endogenous
Internal cause or origin
