1. Chromosomes

2. Chromosomes Defined: Tightly coiled DNA Form when cells divide
Chromosomes created for the new cells
2 Parts:
1) Chromatids: two identical parts of a chromosome
2) Centromere: Joins chromatids together
Chromosomes

3. Karyotype Female Male Defined: Picture of an individuals chromosomes
Help identify sex & chromosome defects
Size of final pair identifies sex
Same size: XX = female
Different size: XY = male
Normal human will have 46 chromosomes
Female
Male

4. Down Syndrome: What’s Wrong?
Writing notation:
1st: total chromosome #
2nd: Sex chromosomes
3rd: extra or missing
Down Syndrome
47,
XY,
+21

5. Turner’s Syndrome: What’s Wrong?
Write the notation for Turner’s Syndrome.
45, X, -23 or
45, XO, -23

6. Patau’s Syndrome: What’s Wrong?
Write the notation for Patau’s Syndrome.
47, XY, +13

7. Klinefelter’s Syndrome: What’s Wrong?
Write the notation for Klinefelter’s Syndrome.
47, XXY, +23

8. Diploid Cells Diploid Cells = Cells with the full set of chromosomes
Paired chromosomes
Half of our chromosomes come from each parent (23 from each parent)
Somatic (non-sex) cells are diploid
Created by mitosis
Ex: Skin, Muscle, Nerve, Blood Cells

9. Haploid Cells
Haploid Cells = Cells with ½ the total number of chromosomes
Gametes (sex cells) are the only haploid cells
Ex: Sperm, Egg, Pollen
Created by meiosis
Chromosome number reduced by 1/2
How do humans get 46 chromosomes?
Haploid sperm cell (23)
+ Haploid egg cell (23)
= Diploid zygote (46)

10. Diploid Karyotype Haploid Karyotype
Because diploid cells have the full set of chromosomes, you will see chromosomes paired.

11. Rat
Karyotype
Is this a male or female rat?
male

12. Rat
Karyotype
What is the diploid chromosome number? 42

13. Rat
Karyotype
What is the haploid chromosome number? 21

14. Rat
Karyotype
How many chromosomes would be in somatic cells? 42

15. Rat
Karyotype
How many chromosomes would be in brain cells? 42

16. Rat
Karyotype
How many chromosomes would be in gamete cells? 21

17. Rat
Karyotype
How many chromosomes would be in egg cells? 21

18. Rat
Karyotype
How many chromosomes would be in muscle cells? 42

19. Rat
Karyotype
How many chromosomes would be in sperm cells? 21

20. Review
1) What is the difference between chromatin, chromatids, and chromosomes?
2) Name the location where chromatids connect.
3) Examine the karyotype.
What the haploid number?
Diploid number?
Somatic number?
Gamete number?
4) Which of the following cells are created by mitosis?
Skin Nerve Sperm Brain Kidney Stomach Pollen
5) Which of the following cells are created by meiosis?
6) Which of the following cells are haploid?
7) Which of the following cells are diploid?