1. Human Genetics – Studying Chromosomes & Diseases
Biology

2. Karyotype
A picture of a person’s chromosomes, arranged in pairs and ordered from largest to smallest

3. Why would a doctor perform a karyotype?
If the woman is over 35 (eggs are older)
If there are chromosome diseases in the family
If a child or adult has symptoms of a chromosome disorder
If an adult is having a hard time getting or staying pregnant

4. Where do the chromosomes come from?
Blood samples (for adults or infants)

5. Where do the chromosomes come from?
Chorionic Villi Sampling (for fetus)
Cells in the “roots” around the unborn baby are analyzed

6. Amniocentesis (for fetus)
Cells in the fluid around the unborn baby are analyzed

7. Embryo after cleavage A single cell is removed from the embryo
Performed for in vitro fertilization

8. How do chromosome problems occur?
Problems with Meiosis
Chromosomes fail to separate properly
Results in too few or too many chromosomes in offspring
Often fatal, but some exceptions

9. Trisomy 21 – Downs Syndrome
Tri = 3, so Trisomy 21 is 3 chromosome 21’s
Mental impairment
Upward-slanted eyes
Slightly flattened facial features

10. Klinefelter Syndrome Males with 2 X chromosomes (XXY) Male appearance
Some feminine traits (breasts, higher pitched voice)
Sperm count is low
Hormone injections can help

11. Turner’s Syndrome Have single X but no other sex chromosome (XO)
Female appearance
Tend to be very short
Affects sexual development
Hormone injections help

12. Pre implantation Diagnosis
A test used prior to implantation to help identify genetic defects within embryos
Checks for chromosomal issues before placing the embryo in the mother
Can also be used for gender selection