Mitosis & the Cell Cycle

1. Mitosis & the Cell Cycle Courtesy of Mill Creek

2. Cell Growth & Development • Are cells of organisms the same size? Do your cells get bigger as you grow, or do you just produce more cells? • When talking about Cell Size…… Smaller is Better! • The larger a cell becomes, the more demands the cell places on its DNA, and the harder it is to supply with nutrients.

3. Cell Division • Before a cell becomes to large, a growing cell will divide. • Cell division is the process by which a Single cell divides into 2 Daughter cells. • Cell Division = the series of events that cells go through as they grow and divide.

4. WHAT TO COPY • COPY THE NOTES IN YELLOW

5. Chromosomes • Chromosomes= are composed of DNA-Which carries the cell’s coded genetic information. • Humans have 46 chromosomes(23pairs). • The chromosomes consist of twoidentical sister chromatids.

6. Two Major Types of Cell Division • Mitosis- Somatic cells (Body Cells) • Diploid 2N • Meiosis- Sex cells/ Gametes • Haploid 1N

7. Mitosis • Mitosis is the process by which the genetic information is replicated and distributed to daughter cells. • 2 diploid(2N) daughter cells are produced from 1 diploid (2N) parent cell. • The Daughter cells are genetically identical to the parent cell. • There are 4 major stages to mitosis, PMAT. Mitosis does NOT include interphase.

8. Interphase • Interphase= The cell spends most of its life here; not part of the actual reproduction. NOT PART OF MITOSIS. • Cell grows and replicates its DNA and centrioles. • Nuclear membrane is visible • Nucleus, Nucleolus, and chromatin can be seen.

9. Interphase

10. Prophase • Prophase: first phase of Mitosis • Nuclear membrane breaks down • Chromosomes become visible • Centrioles separate • Spindle forms

11. Metaphase • Metaphase: Second part of Mitosis • Chromosomes attach to spindle • Chromosomes line up across the center of the cell

12. Anaphase • Anaphase: Third step in Mitosis • The sister chromatids separate and move apart towards opposite poles. The chromatids are now called chromosomes.

13. Telophase • Telophase: Fourth stage of Mitosis • Chromosomes gather at opposite ends of the cell • The nuclear membrane begins to form and enclose the chromosomes • Cell membrane begins to move inwards

14. Cytokinesis • Cytokinesis: Final stage in cellular division • Not Mitosis • Works with telophase • The cytoplasm divides completely in half. • 2 daughter cells with identical genetic information are produced.

16. MEIOSIS Sex cells and gametes

17. Meiosis is the process by which sex cells/ gametes are produced. • These sex cells are diploid (1N).

18. Human body cells have 46 chromosomes • Human sex cells, sperm and eggs, have 23 chromosomes.

19. Why should gametes have only half the number of normal chromosomes??? • During meiosis, FOUR haploid daughter cells are produced from ONE diploid parent cell.

20. During meiosis the cell actually divides TWICE Meiosis I and Meiosis II

21. Figure 11-15 Meiosis Section 11-4 Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

22. MEIOSIS I • Prophase I: a. Homologous chromosome pairs move together, to form a tetrad. b.Nuclear membrane disappears c. Crossing-over may occur

23. Figure 11-15 Meiosis Section 11-4 Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

24. Crossing-Over Section 11-4 Go to Section:

25. Crossing-Over Section 11-4 Go to Section:

26. Crossing-Over Section 11-4 Go to Section:

27. MEIOSIS I • Metaphase I: a. Tetrads line up at the Equator.

28. Figure 11-15 Meiosis Section 11-4 Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

29. MEIOSIS I • Anaphase I: a. ONEhomologous chromosome of each pair gets pulled to opposite poles. b. The sister chromatids do not separate.

30. Figure 11-15 Meiosis Section 11-4 Meiosis I Interphase I Prophase I Metaphase I Anaphase I Cells undergo a round of DNA replication, forming duplicate Chromosomes. Each chromosome pairs with its corresponding homologous chromosome to form a tetrad. Spindle fibers attach to the chromosomes. The fibers pull the homologous chromosomes toward the opposite ends of the cell. Go to Section:

31. MEIOSIS I • Telophase I and Cytokinesis: • Cells separate; two new cells are formed that are HAPLOID. • Nuclear membrane REFORMS.

33. Interphase occurs between meiosis I and meiosis II to prepare the cell for division again

34. MEIOSIS II • Process occurs like mitosis and sister chromatids separate into separate cells. Results in 4 haploid (1N) daugther cells.

35. Figure 11-17 Meiosis II Section 11-4 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. Go to Section:

36. Figure 11-17 Meiosis II Section 11-4 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. Go to Section:

37. Figure 11-17 Meiosis II Section 11-4 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. Go to Section:

38. Figure 11-17 Meiosis II Section 11-4 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. Go to Section:

39. Figure 11-17 Meiosis II Section 11-4 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. Go to Section: