Meiosis

1. Meiosis The formation of gametes (sex cells)

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

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

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

5. What is Meiosis? Meiosis involves two divisions • Meiosis I • Meiosis II

6. 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.

7. What is Crossing Over? Crossing over is when twohomologous 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.

8. Crossing Over

9. Crossing Over

10. Crossing Over

11. Meiosis I

12. Meiosis I

13. Meiosis I

14. Meiosis I

15. Meiosis I

16. Meiosis II Very similar to mitosis FINAL PRODUCT = 4 HAPLOID DAUGHTER CELLS

17. 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.

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. Gamete Formation Males Females 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. • In male animals, the haploid gametes produced in meiosis are called sperm.

23. Gamete Formation Males Females Oogenesis Spermatogenesis

24. To produce gametes (sex / gametic cells) Production of body 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