1. Chromosomes

2. Chromosomes Defined: Tightly coiled DNA Forms during cell division
New chromosomes created for 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
Identify sex & chromosome defects
Size of final pair identifies sex (Chromosome #23)
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. What is the human diploid chromosome number?
Remember…Diploid = total number of chromosomes Answer = 46

10. What is the human somatic chromosome number?
Remember…Somatic cells are non-sex cells… …Somatic cells are diploid… …Diploid cells have the full set of chromosomes Answer = 46

11. How many chromosomes are in brain cells?
Remember…Brain cells are non-sex cells… …Somatic cells are non-sex cells… …Somatic cells are diploid… …Diploid cells have the full set of chromosomes Answer = 46

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

13. What is the human haploid chromosome number?
Remember…Haploid = half number of chromosomes Answer = 23 chromosomes

14. What is the human gamete chromosome number?
Remember…Gamete cells are sex cells… …Sex cells are haploid… …Haploid cells have ½ the set of chromosomes Answer = 23

15. How many chromosomes are in female egg cells?
Remember…Egg cells are sex cells… …Sex cells are gametes… …Gamete cells are haploid… …Haploid cells have ½ the set of chromosomes Answer = 23

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

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

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

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

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

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

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

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

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

26. Quick Review Chromsomes are tightly coiled strands of DNA
Diploid (somatic) cells contain the entire set of chromosomes
Haploid (gametes) cells contain only ½ the total number of chromosomes