PAP Biology

● Chromosomal mutations …
– Additional, missing, or damaged chromosomes cause several human genetic disorders.
– One way of studying these disorders is to observe the chromosomes themselves.

tool used to determine the sex of an individual or detect/identify chromosomal abnormalities .

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 .

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 karyptypes

• 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 .
• In humans, pairs 1-22 homologs are called AUTOSOMES .
Autosomes transmit all genetic traits and conditions.
• Pair 23 determines the individual’s sex so that pair is referred to as the SEX
CHROMOSOMES .

We are going to view some Karyotypes and determine if there is a disorder and what kind of disorder (mutation)

Station 1

1b

2
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.

3
Turner Syndrome

• 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 .

4
Patau Syndrome

• 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.

5
Klinefelter Syndrome

• 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.

6
Edwards Syndrome

• 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.

7
Triple-X Syndrome

• 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.

8
XYY Syndrome

• Males only.
• Affects pair 23.
• Extra copy of the Y chromosome.
• Taller than average.
• Increased risk of learning disabilities.
• Prone to severe ache.
• May include antisocial or behavioral problems.