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Human
Chromosome
Mutations
Get out spiral
Grab packet off front table
2 Main Types of Mutations
1.) Chromosomal Mutations
2.) Gene Mutations
(What we did yesterday)
Chromosomal Mutations
Chromosomes are your DNA!!!
Any change in the structure or
number of chromosomes
Large scale: Affect many genes
What are chromosomes?
DNA!!!
Humans have 23 pairs
of chromosomes, with
one chromosome from
each parent. (46 total)
Overview Meiosis
meiosis  fertilization  mitosis + development
gametes
Mom
46
meiosis
Dad
23
23
egg
23
46
23
zygote
fertilization
sperm
46
46 46
46 46 46
46
46
46
mitosis
&
mitosis
development
Types Chromosomal
Mutations
1.
2.
3.
4.
Duplication
Inversion
Translocation
Non Disjunction
Chromosomal Duplication
A segment of genes is copied twice and added to
the chromosome
Causes:
Charcot–Marie–Tooth disease
(high arched foot, claw feet, confined to a wheelchair)
Chromosomal Inversion
a segment of genes flip end-to-end on the chromosome
Causes:
Four-Ring Syndrome
(cleft pallate, club feet, testes don’t descend)
Chromosomal Translocation
Material is swapped with another chromosome
Causes:
Promyelocytic Leukemia
(translocation of chromosomes 15 and 17)
Nondisjunction
the failure of one or more pairs
of chromosomes to separate
normally during cell division
Produces gametes (sperm and egg) (and
therefore a baby) with one missing
chromosome or one extra chromosome
Down Syndrome
Cause:
Nondisjunction of
chromosome 21
Three copies of chromosome
21 =
“TRISOMY 21”
Chromosomal Mutations
Most chromosomal mutations
are lethal
If the fetus survives: Tend to
cause wide-spread abnormalities
Example: Down Syndrome
Trisomy 21 - Down Syndrome
Mutation Practice
Normal Chromosome
ABCDEFGH
A B C F E D G H Mutated Chromosome
Inversion
Mutation Practice
Normal Chromosome
ABCDEFGH
A B C C D D E F G H Mutated Chromosome
Duplication
Mutation Practice
Normal Chromosome
ABCDEFGH
JKLMNOPQ
A B C D J K L M Mutated Chromosome
NOPQEFG H
Translocation