Karyotypes and Mutations

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Karyotypes and Mutations
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Karyotype

• An orderly display of magnified images of the
  individuals chromosomes
• Shows the
  chromosomes as
  they appear in
  metaphase.

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What is a Normal Karyotype?

• We are supposed to have 46 total chromosomes in
  each cell (22 pairs of autosomes 44, 2 sex
  chromosomes).

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One sourceAmniocentesis

• Take fluid from amniotic fluid around the baby
• Can make a karyotype to see if there is a genetic
  disorder

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Preparing a Karyotype

• 1. Use blood cells.

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Essay Preparing a Karyotype

• 2. Burst RBC (red blood cells) in hypotonic
  solution.
• Release WBC (white blood cells).

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Essay Preparing a Karyotype
3. Use a centrifuge to separate the white blood
cells from the rest of the blood fluid
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Preparing a Karyotype

• 4. Add chemical (colchicine) to stop the
  chromatids in metaphase (stops spindle fibers
  from forming)

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Preparing a Karyotype (cont)

• 5. Drop on a slide.

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Preparing a Karyotype (cont)

• 5. Take a picture
• 6.Sort by size and shape from largest to smallest

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Other types of Karyotypes
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Types of Karyotypes

• Fluorescent to detect a marker showing certain
  defect

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Types of Karyotypes

• Colored dyes for certain chromosomes

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Types of Karyotypes

• Ideogram bands locate sites on chromosome

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Normal Karyotype

• WHY?
• Is it a Male or a female?

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Down Syndrome Karyotype

• Trisomy 21

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Down Syndrome

• Trisomy 21
• Folds over eyes
• Sluggish muscles
• Mental Problems

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Down Syndrome

• The most common
  chromosome number
  abnormality
• Round face
• flattened nose bridge
• small, irregular teeth

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Down Syndrome

• Short Stature
• heart defects
• susceptibility to
  respiratory infection ,
  leukemia and
  Alzheimers

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Does the mothers age matter?

• As the age of the mother increases above 30, the
  frequency of Trisomy 21 also increases

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Abnormal Sex Chromosomes

• 47 XXY syndrome
• male
• testes small (sterile)
• breast enlargement
• feminine body contours
• also XXYY, XXXY, XXXXY

• Klinefelters

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TURNER SYNDROME

• XO (only one X)
• short
• often web of skin between neck and shoulders
• sterile
• poor breast development

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Turner Karyotype
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What about

• MUTATIONS?

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(No Transcript)
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DELETION
Fragment of the chromosome is lost
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Duplication
Fragment of one chromosome attaches to a
homologous chromosome
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Translocation
Fragment reattaches in reverse direction (less
likely to produce harm)
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INVERSION

• The chromosome breaks in two places, a piece of
  the chromosome is removed and the chromosome
  pieces remaining rejoin.

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Inversions

• Inversions, by definition, do not involve loss or
  gain of chromosomal material.

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INVERSION 46,XY,inv(16)

• The left one is normal and the right one is
  inverted near the centromere.

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45,XX,rob(13,14) A Robertsonian translocation
(an end to end fusion of 13 and 14) There is no
net gain or loss of genetic material
in
this person so they would
have a normal

phenotype.
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Applications

• Chromosomes from the father of a retarded
  child... a portion of
• chromosome 11 (blue) has been
• transfered to chromosome 1(yellow).