1. Chromosomes

2. Defined: Tightly coiled DNA
Chromosomes

3. Chromosomes Defined: Tightly coiled DNA Form when cells divide
Chromosomes created for the new cells
Chromosomes

4. 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
centromere
left chromatid
right chromatid

5. Karyotype Female Male Defined: Picture of individual 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 per cell
Female
Male

6. Types of chromosomes

7. I’m seeing something that concerns me a little bit
I’m seeing something that concerns me a little bit. I think we should consider a karyotype.
It’s hard to know. Once we examine the baby’s chromosomes we will have more information.
Oh no!
Is it serious?

8. Doctor:
I’m gonna insert this needle and suck up some fluid. Cells from the baby should be in this fluid.
Now that cells have been obtained, chromosomes can be seen and photographed

9. Under a microscope, the stained chromosomes are randomly scattered.

10. The lab technician arranges the chromosomes into pairs so the karyotype can be analyzed.

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

12. Turner’s Syndrome: 30 seconds to discuss with your neighbor.
Write the notation for Turner’s Syndrome.
45, X, -23 or
45, X0, -23

13. Patau’s Syndrome: 30 seconds to discuss with your neighbor.
Write the notation for Patau’s Syndrome.
47, XY, +13

14. Klinefelter’s Syndrome: 30 seconds to discuss with your neighbor.
Write the notation for Klinefelter’s Syndrome.
47, XXY, +23

15. Diploid Cells Diploid Cells: Cells with full set of chromosomes
Paired chromosomes
Humans: 23 pairs; 46 total
Somatic (non-sex) cells are diploid
Ex: Skin, Muscle, Nerve, Blood Cells
Created by mitosis

16. 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 half

17. I’m half mom and half dad.
How do humans get 46 chromosomes?
These 23 chromosomes are in the egg cell of mom.
These 23 chromosomes are in the sperm cell of dad.

19. Zygote (fertilized egg) is created
23 chromosomes
23 chromosomes 46
23 chromosomes
23 chromosomes
23 chromosomes
23 chromosomes
Zygote (fertilized egg) is created

20. 46 46 46 46
Zygote divides by mitosis
9 months later…

21. Diploid karyotype: Chromosomes in pairs
Haploid Karyotype
Diploid karyotype: Chromosomes in pairs
Haploid karyotype:
Single chromosome

22. 1 Minute: Discuss this rat karyotype with your neighbor.
Gender?
Number of chromosomes in a somatic cell?
In a skin cell?
In a gamete?
In a diploid cell?
In a sperm cell?
female 42 42 21 42
Notice there are 21 pairs of chromosomes 21

23. 1 Minute: Discuss this gorilla karyotype with your neighbor.
Number of chromosomes in a haploid cell?
gamete?
In a muscle cell?
In a zygote?
In an egg cell? 24 24 48 48
Notice there are 24 pairs of chromosomes 24

24. Quiz
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?

25. 8) Left, Middle, or Right: Which karyotype is from a diploid cell?
9) Left, Middle, or Right: Which karyotype could be from a muscle cell?
10) Left, Middle, or Right: Which two karyotypes could be from a sperm cell?
11) Left, Middle, or Right: Which karyotype is from an egg cell?
12) Left, Middle, or Right: Which two karyotypes are from a haploid cell?