Karyotyping Notes and Activity Pages. ●Chromosomal mutations… – Additional, missing, or...
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Transcript of Karyotyping Notes and Activity Pages. ●Chromosomal mutations… – Additional, missing, or...
KaryotypingNotes and Activity Pages
●Chromosomal mutations…– Additional, missing, or damaged chromosomes
cause several human genetic disorders.– One way of studying these disorders is to
observe the chromosomes themselves.
Why do scientists study chromosomes?
Karyotypes are treated with chemicals that stops cell division at the metaphase stage.
During metaphase, the chromosomes are at the best/longest length for identification.
Karyotyping – tool used to determine the sex of an
individual or detect/identify chromosomal abnormalities.
Humans have 46 chromosomes in every diploid (2n) body cell. The chromosomes of a diploid cell occur in HOMOLOGOUS PAIRS, which are pairs of chromosomes that are similar in size, shape, and the position of their centromere.
The cells are stained, and then placed on glass slides. The chromosomes are observed under the microscope and then photographed. There 2 chromosomes in each place on a karyotypes
• In humans, pairs 1-22 homologous are called AUTOSOMES. Autosomes transmit all genetic traits and conditions.
• Each homologous and alike. (common)
• Pair 23 determines the individual’s sex so that pair is referred to as the SEX CHROMOSOMES.
AND NOWWWWW…We are going to view some Karyotypes and determine if there is a disorder and
what kind of disorder (mutation)
Normal Female Karyotype(XX at pair 23)
Station 1
Normal Male Karyotype (XY at pair 23)
1b
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Down Syndrome
Down’s Syndrome• Female.• Trisomy 21, extra
chomosome in pair 21.• Down syndrome is one
of the most common chromosomal disorders.
• Physical and mental development is slower.
• Flat facial profile.• Broad forehead.• Thick tongue.• Upward slant to the
eyes.• Short arms and legs.
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Turner Syndrome
TurnerSyndrome• Females only.• Affects pair 23.• Results from a missing or
incomplete sex chromosome.
• Turner syndrome can cause a variety of problems:• Short stature.• Web neck.• Failure to begin
puberty.• Infertility.• Heart defects.• Learning disabilities.
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Patau Syndrome
PatauSyndrome• Female.• Trisomy 13; extra
chromosome in pair 13.• Least common and most
severe of the trisomies.• Survival is less than 3
days.• Heart defects.• Incomplete brain
development.• Unusual facial features
such as small or missing eyes, low set ears.
• Extra fingers and toes.• Spinal defects.
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Klinefelter Syndrome
KlinefelderSyndrome• Males only.• Affects pair 23.• XXY syndrome.• Affects the male
hormonal development due to an extra X chromosome.
• Lack of testosterone can cause less facial and body hair, breast enlargement, and infertility.
• Taller than the average male; longer arms.
• Skinny with wider hips and less muscular structure.
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Edwards Syndrome
Edward’sSyndrome• Female.• Trisomy 18; extra
chromosome in pair 18.• More than 130
individual defects of the craniofacial structures, brain, heart, kidneys, and gut.
• Small mouth, jaw, and short neck.
• Back of skull is prominent.
• Malformed ears.• Clenched fists with
overlapping fingers; flexed legs and feet.
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Triple-X Syndrome
Triple-XSyndrome• Female.• Trisomy X; extra X
chromosome at pair 23.• Taller than average.• No unusual physical
features.• Increased risk of learning
disabilities and delayed development of speech and language skills.
• Weak muscle tone.• Behavioral and
emotional difficulties.
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XYY Syndrome
XYYSyndrome• Males only.• Affects pair 23.• Extra copy of the Y
chromosome.• Taller than average.• Increased risk of
learning disabilities.• Prone to severe acne.• May include antisocial
or behavioral problems.