Mutations Flashcards
What is a mutation ?
- a change in the DNA of an organism.
- the ultimate source of genetic variation introducing new alleles into a population.
What are the two types of mutations ?
- Gene or point mutation – affecting a single gene.
- Chromosome mutation – affecting a single chromosome or set of chromosomes.
What is substitution mutation?
When one nucleotide is replaced by another
What is synonymous mutation?
when the substituted base results in a codon that codes for the same amino acid as the original codon.
( no effect )
What is missense mutation ?
a single nucleotide substitution changes the amino acid in the polypeptide chain.
What is a nonsense mutation?
a single point mutation creates a new stop codon within the original gene sequence leading to early termination of translation of the transcribed gene sequence.
( premature stop codon )
What is insertion?
The addition of one or more nucleotides at a site within the original gene sequence.
What is deletion ?
The loss of nucleotides from a site within the original gene.
What is frameshift ?
the reading frame for the corresponding amino acids being nudged away from the original position and all the codons downstream of the mutation being affected.
What are 3 groups of mutations ?
- physical
- chemical
- biological agents
What are examples of physical mutations ?
- Gamma rays
- Beta rays
- Alpha rays
- UV radiation
- X ray
What are examples of chemical mutations?
- mustard gas
- nitrous oxide
- 5 bromouracil
What are examples of biological agents ?
- hepatitis B virus
- Rubella virus
- cytomegalovirus
