Mutations Flashcards
(30 cards)
What is a mutagen?
Any agent causing a mutation
4 types of mutations
Point mutations
Insertions or deletions
Gene duplication
Chromosomal changes
What are the 3 causes of mutations?
DNA polymerase errors
External effects (chemical or radiation)
Failure of repair mechanisms
Should there be a high or low level of mutations for a stable species?
Low
Where do somatic mutations occur?
In somatic cells
Who do somatic mutations effect?
Organisms of mutation
Are somatic mutations inherited or not?
Not inherited
Where do germline mutations occur?
Germline of sexually reproducing organisms
How do germline mutations occur?
Passed on by gametes to next generation
Are germline mutations inherited or not?
Yes in both somatic and germline cells
What are point mutations?
Mutations involving one base pair
2 categories of point mutations
Base-pair substitutions and base-pair deletions/insertions
What are base-pair transitions?
Replacement of a base of the same chemical category (purines and pyrimidines)
What are base-pair transversions?
Replacement of a base of one chemical category by a base of another
What are nonsense mutations?
Change of codon in the ORF to a stop codon
What are missense mutations?
Base-pair change resulting in a different mRNA codon
2 categories of phenotype changes
Neutral and silent mutations
What are neutral mutations?
Change of codon in the ORF but no detectable changes in function of protein
What are silent mutations?
Mutant codon encodes same amino acid as wild-type gene
Where do mutations occur in the cell cycle?
S, G1 and G2 phases
What is another method for mutations?
Movement of transposons
What corrects mutations?
Cellular repair system
3 types of induced mutations
Base analogues, base modifying agents and intercalating agents
How do base analogues cause mutations?
Shift antilog’s form to cause incorrect base pairing during duplication
