L14 - Gene mutations Flashcards
What is mutation?
Mutation is a heredity change in DNA
What are the causes of mutation?
- DNA replication errors
- Spontaneous mutations
- Chemicals and irradiations
What is Somatic mutation?
Somatic mutations are the ones that occur in any cell of the body apart from germ cells (egg and sperm) - these mutations cannot be inherited by offspring
What is germ-line mutation?
occur in gametes - these mutations are inherited by offspring
What is transition mutation?
one purine replaces another, or one pyrimidine replaces another
What is transversion mutation?
a pyrimidine is replaced by a purine or vice versa
What are the three types of base-pair substitution?
1) Silent mutation
2) Missense mutation
3) Nonsense mutation
Promoter mutations
mutations that alter consensus sequence nucleotides of promoters - these interfere with efficient transcription initiation
Splicing mutations
Mutations that alter nucleotides required for efficient splicing at intron-exon junctions
Forward mutation
converts a wild type allele to a mutant allele
Reverse mutation
convert mutant alleles to wild type allele or near wild type allele
True reversion
wild type DNA sequence is restored by a second mutation within the same codon to change the amino acid back to the wild type one
Second site reversion
occurs by mutation in a different gene and together the two mutations restore the organism to wild type
Mutagenesis is…
the process of inducing mutations by mutagens
Intercalating agents
Are flat and planar molecules that intercalate between the base pairs distorting the DNA helix which disrupts DNA replication and causes addition and deletion of nucleotides. leading to frameshift mutations
