1. Karyotyping

2. Fertilization spermeggzygote The fusion of a sperm and egg to form a zygote. A zygote is a fertilized egg n=23 egg sperm n=23 2n=46 zygote

3. Karyotype A karyotype-a diagram showing a cell’s chromosomes in order-largest to smallest- from mom and dad. Made from a picture of the chromosomes during metaphase.

4. Abnormalities Chromosomal abnormalities often result from nondisjunction-failure of the chromosomes to separate properly during meiosis. This causes a cell to have too many chromosomes or too few. Abnormal chromosome number is called aneuploidy.

5. Trisomy Cells have an extra chromosome. Have 47 instead of 46. Trisomy 21- three chromosomes on the 21 causes Down syndrome.

6. Monosomy A cell is missing a chromosome. A cell has 45 chromosomes instead of 46. Turner’s syndrome-missing an X at pair 23.

7. Karyotypes