Unit 18- mutations Flashcards
mutations
inherited alterations in the DNA seq
- source of genetic variation
- source of many diseases and disorders
adaptive mutation
- genetic variation critical for evolutionary change that brings about adaptation to new environments
- stressful conditions, where adaptation might be necessary to survive, induce increased mutation in bacteria
causes of mutations
- spontaneous replication error
- spontaneous chem changes
- chemically induced mutations
- radiation
Big categories of mutations
- somatic mutations (all cells derived from that cell with have the mutation)(mitosis)
- germ-line mutations (offspring that came from mutant cell will be completely mutated)(meiosis)
base substitution: transition
the substitution of a purine for a purine or of a pyrimidine for a pyrimidine
base substitution: transversion
substitution of a pyrimidine for a purine or of a purine for a pyrimidine
insertions and deletions: frameshift
affects the reading frame
insertions and deletions: in-frame
does not affect the reading frame
expanding nucleotide repeats
increase the number of copies of a set of nucleotides (fragile sites)(hairpins. 2/3 bases pairing)
forward mutation
wild type —> mutant type
reverse mutation
mutant type —> wild type
missense mutation
amino acid —> diff amino acid
nonsense mutation
sense codon —> stop codon
synonymous mutation
change the base but don’t change amino acid
silent mutation
codon —> synonymous codon (no change in AA seq!)
neutral mutation
no change in function
phenotypic effects of mutations
- loss-of-function mutation
- Gain-of-function mutation
- Lethal mutation
Suppressor mutation
a mutation that hides or suppresses the effect of another mutation
- Intragenic (second mutation at diff site in SAME GENE hides mutation in another site)
- Intergenic (mutation in second gene that hides mutation in first gene)
