Download Mutation Notes What is a MUTATION? Any change made to the DNA

Mutation Notes
What is a MUTATION?
Any change made to the DNA
Do all mutation cause a change in a trait? Not always, it depends on location of mutation and type
Mutations can be inherited from parent to child or acquired due to environmental damage or mistakes
in replication
Mutations happen regulary and are usually nuetral . Many mutations are repaired by enzymes. Some
mutations may improve an organism’s chances of survival.
CHROMOSOMAL MUTATIONS: May involve changing the structure or number of chromosomes.
Type of CHROMOSOMAL Mutation
Definition and example
A piece of a chromosome is lost, due to breakage.
Deletion
ABCD-EFGH  ABCD-EF
Inversion
Chromosome segment breaks off, flips, and is reattached
backwards.
ABCD-EFGH  ABDC-EFGH
Occurs when a gene sequence is repeated.
Duplication
ABCD-EFGH  ABCDBCD-EFGH
Translocation
Involves two chromosomes that aren’t homologous. Part of
one is transferred to another chromosome.
ABCD-EFGH WXY-Z  ABCD-EF WXY-ZGH
Nondisjunction
Failure of chromosomes to separate during meiosis. Results in
too many or too few chromosomes.
Examples: Down syndrome, Turner syndrome, Klinefelter’s
syndrome.
Examples of disorders resulting from Chromosomal Mutations
Down Syndrome- Chromosome 21 doesn’t separate = trisomy 21

Slow development, varied levels of mental handicaps, similar facial features
Cri-du-chat- Deletion of material on the 5th chromosome

Cat like cry when babies, varied levels of mental handicaps
Klinefelter’s Syndrome- Nondisjunction: X chromosome fail to separate.
 Occurs in males when they receive an extra X chromosome (XXY, XXXY). Sterile, small testis,
develop breasts
XYY Syndrome- Male, often tall and thin, often associated with anti-social and behavioral problems
Turner’s Syndrome- Nondisjunction: X chromosomes fail to separate

Female (X), sex organs don’t mature, sterile, short stature.
XXX - Trisomy X

Female, tall, learning disabilities, limited fertility, little or no visible difference.
Karyotype: Picture of paired chromosomes arranged by size, used to identify abnormalities in fetus
Autosomes: Pairs 1-22. Body chromosomes
Sex Chromosomes: Pair 23. X and Y Female: XX Male: XY
Male or Female?