1. Cool Stuff about Chromosomes

2. Y they’re X-cellent
Sex chromosomes – determine whether the offspring is male or female
Females: XX
Males: XY

3. Boy or Girl?

4. Who determines the gender of the offspring?

5. King Henry VIII

6. Autosomes – all of the non-sex chromosomes
How many chromosomes are autosomes? How many are sex chromosomes?

7. Studying Chromosomes
Karyotype – a photograph of all an organism’s chromosomes

8. How are karyotypes made?
Scientists use chemicals to freeze cells at the metaphase stage of cell division
Easy to isolate and easy to stain

9. Arrange the chromosomes

10. Reading a chromosome Look at 3 things: Size Banding pattern
Centromere position

13. Genome
Genome – the base sequence of all the DNA in an organism

14. What is The Human Genome Project?
Find the sequence of all the DNA in the human body
“read” 23 chromosomes which contain about 90,000 genes with more than 3 billion bases.

15. Cracking the Code of Life

16. Chromosomal Abnormalities
Karyotypes can be used to show chromosome abnormalities
Too many or too few chromosomes

17. Chromosomal Abnormalities
Nondisjuction – chromosomes fail to separate correctly during mitosis or meiosis
Mitosis

18. Nondisjuction
Meiosis
Abnormal gametes

19. Nondisunction
Monosomy – zygote has only one copy of a particular chromosome

20. Nondisunction
Trisomy – zygote has three copies of a chromosome

21. What’s wrong with the karyotype?

22. Trisomy 21
Down syndrome

23. Down Syndrome – most common chromosome abnormality in humans
Lower cognitive ability, Flattened face with angled eyes, Shorter stature (5’1, 4’9), Usually infertal

24. What’s wrong with this karyotype?

25. XXX
Triple-X
Not severe symptoms - Slight learning disabilities, usually tall
Fertile with rare chance of passing on disease

26. What’s wrong with this karyotype?

27. XXY Klinefelter syndrome
Symptoms include learning disabilities, slight breast development, wider hips, underdeveloped male organs, and infertility.

28. What’s wrong with this karyotype?

29. X0
Turner syndrome
Symptoms include short child like stature, underdeveloped female organs, low hairline, neck webbing, and infertility.