1. Genetics: Karyotypes

2. Chromososmes
Traits are passed on to you from your parents through chromosomes.
Half of your chromosomes come from your father and half from your mother.

3. Karyotype – An ordered arrangement of a person’s chromosomes

4. Sex Chromosomes vs. Autosomes
Sex Chromosomes (23rd pair)– The X and Y chromosomes which determine a person’s sex
Which sex is XY? Male
Which sex is XX? Female
Autosomes – Paired chromosomes 1-22, same in both sexes

5. How Karyotypes are Made
Cells of a person or fetus are photographed during mitosis when the chromosomes are condensed and easy to see - Prophase

6. How Karyotypes are Made
The photograph is then cut and the chromosomes are arranged in order of size

7. Amniocentesis – taking the fluid from around a fetus to make a karyotype

8. Normal Human Karyotype
23 pairs of Chromsomes
Autosomes
23 - sex chromosomes

9. Karyotype Abnormalities
Monosomy- having one chromosome rather than a pair
Trisomy – having three chromosomes rather than a pair
Both occur because of nondisjunction during meiosis

10. Nondisjuction – when a doubled chromosome doesn’t split during meiosis
These 4 cells will each become eggs or sperm, two of which will have abnormal numbers of chromosomes. Which two?

11. Trisomy 21 = Down’s Syndrome

12. Down Syndrome Happens 1 in 700 births
Individuals have broad, flat faces, mild to moderate mental retardation, and sometimes respiratory problems
Usually live slightly shortened life-spans

13. Trisomy 18 = Edward’s Syndrome

14. Edward’s Syndrome Happens 1 in 10,000 births
Individuals have malformed ears and hands, mental retardation, and heart disease
Most don’t live past a few years

15. 47, XXY = Kleinfelter’s Syndrome

16. Kleinfelter’s Syndrome
Happens 1 in 1000 male births
Individuals are sterile, have some feminine characteristics such as breast enlargement and little facial hair, normal intelligence

17. Monosomy X = Turner’s Syndrome

18. Turner’s Syndrome Happens 1 in 5000 female births
Individuals do not develop sexually during puberty and are sterile, but have normal intelligence
The only monosomy that is survivable in humans!

19. What can you tell about this person from their karyotype?

20. Now, get out a piece of paper for the Karyotype Lab
Do not write on the paper
Following the instructions

21. 1. Billy Will
3. Tommy (left)
4. Suzy Jen