2. The formation of gametes (sex cells)
Meiosis
The formation of gametes (sex cells)

3. Some Vocab n Haploid (n): one set of chromosomes
Reproductive cells are haploid (23 Chromosomes in humans)
Eggs
Sperm
Diploid (2n): two sets of chromosomes
You are diploid ( 46 chromosomes in humans)
1 set from mom
1 set from dad n 2n
(23)
(23)

4. Some Vocab
Homologous Chromosomes: two chromosomes with the same gene sequence as another, one from each parent.

5. What is Meiosis?
Meiosis is a process of reduction division in which the number of chromosomes per cell is cut in half.

6. Meiosis involves two divisions
What is Meiosis?
Meiosis involves two divisions
Meiosis I
Meiosis II

7. Meiosis I Interphase I – DNA replicates
Prophase I – Crossing over occurs
Metaphase I – Chromosomes line up
Anaphase I – Chromosomes are pulled apart
Telophase I/Cytokinesis – Nuclear membranes forms. The cell separates into two cells.

8. What is Crossing Over?
Crossing over is when two homologous chromosomes pair up and exchange segments of their genetic material.
Crossing over results in genetic recombination.
Crossing over is what makes every egg and sperm cell unique.
Crossing over is why you are not exactly like your siblings.

9. Crossing Over

10. Crossing Over

11. Crossing Over

12. Meiosis I

13. Meiosis I

14. Meiosis I

15. Meiosis I

16. Meiosis I

17. Meiosis II
Very similar to mitosis FINAL PRODUCT = 4 genetically different HAPLOID DAUGHTER CELLS

18. Meiosis II Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

19. Meiosis II Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

20. Meiosis II Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

21. Meiosis II Prophase II Metaphase II Anaphase II Telophase II
Meiosis I results in two haploid (N) daughter cells, each with half the number of chromosomes as the original.
The chromosomes line up in a similar way to the metaphase stage of mitosis.
The sister chromatids separate and move toward opposite ends of the cell.
Meiosis II results in four haploid (N) daughter cells.

22. Gamete Formation Males Females
In male animals, the haploid gametes produced in meiosis are called sperm.
In female animals, one cell receives most of the cytoplasm and will become an egg cell. The other three cells produced are known as polar bodies and do not participate in reproduction.

24. Gamete Formation
Males
Females
Spermatogenesis
Oogenesis

25. 2 1 1 1 4 2 23 46 No Yes Yes No Meiosis Mitosis Purpose
What kind of cells are produced?
# of divisions required
# of cells needed to begin
# of daughter cells produced
# of chromosomes in daughter cells (n/2n)
# of chromosomes in daughter cells in humans
Are the daughter cells identical to the parent cell?
Does crossing over occur?
To produce gametes
(sex / gametic cells)
Production of body cells (somatic cells) 2 1 1 1 4 2
Half the number of the parent cell (n)
The same number as
the parent cell (2n) 23 46 No
Yes
Yes No