Lesson 8: Chromosomal Mutations Flashcards
Non-Disjunction
An accident of Meiosis or Mitosis in which a
tetrad (in Meiosis) or a pair of sister
chromatids (in Mitosis) fail to seperate
properly
Often Non- Disjunction results in breaking
chromosomesBreaking chromosomes results in 4 types
of chromosome mutations:
1) Deletion
A chromosomal fragment is lost
2) Duplication
A chromosomal fragment from one
chromosome reattaches to its
homologous chromosome creating
a duplicate sequence
3) Inversion
A chromosomal fragment
reattaches to its original
chromosome in the reverse
direction
4) Translocation
A chromosomal fragment is
attached to a non-homologous
chromosome (random
chromosome)
Aneuploidy
An abnormal chromosome number
Non-disjunction can result in an
entire chromosome or
chromosomes that fail to separate
in meiosis which will leave gametes
formed with either too many or too
few chromosomes.
Trisomy – a gamete has
inherited a third copy of a
chromosome
Monosomy – a gamete has
inherited a single copy of a
chromosome
Karyotype
A karyotype is an illustration or
photograph of the chromosomes in the
somatic cell of an organism.
Karyotype
Analysis
The chromosomes are often difficult to
distinguish based on appearance
alone.
They must be stained in order to
reveal the unique banding pattern of
each chromosome.
The chromosomes are matched using
both the size and banding patterns.
The homologous chromosomes are
arranged in order from largest to
smallest with the sex chromosomes
last.
A karyotype can be used to determine
the sex of an individual as well if they
have a chromosomal abnormality
Trisomy 21
Also known as Down’s
Syndrome.
An extra chromosome is
found in position 21
Turner
Syndrome
Results when a person
inherits a single X
chromosome and no Y
chromosome.
This individual is an infertile
woman
Klinefelter
Syndrome
Occurs when two copies of
the X chromosome and a Y
chromosome are inherited.
This individual is a sterile
male.
