7.5 Mutations Flashcards
mutations
caused by synthetic chemicals, radiation, incorrect replication, change function and structure of genome
point mutation
individual base pair mutations
- substiution of one base or another
- insertion or deletion of a single base pair
- inversion of 2 adjoining base pairs
single nucleotide polymorphism
differences in DNA of individuals within populations caused by point mutation
missense mutation
occurs when change of single base pair of group results in code for diff amino acids
nonsense mutations
occurs when change of single base pair or group results in premature stop code in gene
silent mutation
occurs when change in one or more base pairs does not affect function of a gene; mutated DNA sequence codes for same amino acid as non-mutated sequence
frameshift mutation
occurs when one or more nucleotides are inserted or deleted from a DNA sequence causing reading frame of codons to shift in one direction or another
translocation
occurs when entire genes or groups moved from chromosome to another
- if DNA coding sequence translocated adjacent to another coding sequence = new gene and new polypeptide chain
inversion
occurs when part of DNA reverses direction in genome
spontaneous mutation
arise from inaccurate DNA replication
induced mutation
caused by environmental agent
mutagen
environmental agent that directly alters DNA within cell
- can enter cell nucleus and access genome
- 2 most common factors = chemical, radiation
chemical mutagen
any chemical agent that can enter cell nucleus and alter structure of DNA; other chemical mutagens cause mutations by mimicking DNA nucleotide
radiation
- lower energy radiation can cause bonds to break between adjacent nucleotides along DNA strand
- forms kink in backbone of DNA strand and complicate replication and transcription
- higher energy radiation can stop molecules from of electrons and break bond within DNA molecule causing rearrangement or deletion or large portion of chromosomes
