Mutations Flashcards
define mutation
the changing of a gene that results ina variant form that is permenant
define mutagen
any environmental agent that causes a mutation
eg. chemical, biological, physical
What causes a mutation?
- can occur spontaneously
- can be caused by a mutagens
Examples of chemical mutagen agents
exposure to:
* tar
* benzene
* asbestos
Examples of biological mutagen agents
- viruses
- bacteria
- fungi
Examples of physical mutagen agents
high-energy ionising radiation:
* UV light
* x-rays
* gamma rays
What are the 2 different types of mutations?
- point mutations
- chromosomal mutations
What does a point mutation occur with?
a single base pair
What are the 3 types of point mutations?
- point substitution
- point insertion
- point deletion
What happens in a point substitution?
one base is subsituted to another base
the nucleotide is subsituted
What happens in a point insertion?
One base is inserted into the sequence
* FRAMESHIFT occurs: all following bases shift over/are affected
What happens in a point deletion?
One base is deleted from the sequence
* FRAMESHIFT occurs: all following bases shift over/are affected
What is an example of a chromosomal disorder?
trisomy 21
What are the 4 types of chromosomal mutations?
- chromosome deletion
- chromosome duplication
- chromosome inversion
- chromosome translocation
What happens in a chromosome deletion?
a section of the chromosome breaks off and disappears