Mutations Flashcards
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What is a mutation?
A mutation describes changes that occur at the DNA
level that is inheritable.
Mutations can occur by:
Chance
Cell division error
From a mutagen
What are mutagens + examples?
Mutagens are chemical or physical
agents that can cause a mutation to
DNA. They are sometimes called
carcinogens.
- X-rays
- Mustard gas
- UV and nuclear radiation
- Chemicals – benzene, formaldehyde,
tobacco
Mutagens
What are gametic mutations?
Gametic mutations are inherited and occur in the testes of males
and the ovaries of females. These can be passed on to offspring.
What are somatic mutations?
Somatic mutations in body cells. They are not inherited but may affect the person during their lifetime.
What are gene mutations?
Gene mutations occur
when a nitrogen base
(A, T, C, G) is inserted,
deleted or rearranged in
a gene.
What are the two types of
gene mutations?
- Point or substitution
mutations
(One base is substituted for another)
If a substitution changed the amino acid, it’s called a missense mutation
If a substitution does not change the amino acid, it’s called a silent mutation.
If a substitution changed the amino acid to a “stop”, it’s called a nonsense mutation. - Frameshift mutations.
Deletion (a base is lost/deleted)
Insertion (an extra base is added/inserted)
Deletion and insertion may cause what is called a frameshift mutation, thus changing the amino acid sequence from this point forward.
What are chromosome mutations?
- Usually occurs due to
non-disjunction. - Non-disjunction occurs
when chromosomes
don’t separate correctly
during meiosis. - Results in gametes with
too many or too few
chromosomes ->
aneuploidy
Types of chromosome mutations
- Down syndrome – 21 trisomy
- Turner’s syndrome – 1 X only
- Kleinfelter’s syndrome - XXY
Chromosome
mutations
What is aneuploidy?
Gametes with
too many or too few
chromosomes
