1. QOD How many chromosomes do you have? Identify them. How many from your father? Mother?

2. Chapter 8: Cell Reproduction Section 8-1: Chromosomes

3. To return to the chapter summary click escape or close this document. Chromosome Structure

4. Chromosome Structure  Chromosomes = DNA + Proteins  Levels of organization: –DNA –Nucleosome = DNA + Histones –Coils –Supercoils –Chromosome

5. Chapter 8 Chromosome Structure Section 1 Chromosomes

6. To return to the chapter summary click escape or close this document. Chromosome

7. Chromosomes  Before Cell Division –Chromatin –Thinned out  During Cell Division –Thickened –Chromosomes  Chromatids (2)  Centromere

8. Chromosome Types and Numbers  Types: –Sex chromosomes –Autosomes –Homologous chromosomes –Karyotype  Numbers: –Diploid (2n) –Haploid (n)

9. Karyotype

10. Karyotype

11. QOD How many chromosomes does a skin cells have after it divides by mitosis? What happens to ensure this number is achieved? When?

12. Chapter 8: Cell Reproduction Section 8-2: Cell Division

13. Cell Division  In Prokaryotes –Binary fission  In Eukaryotes –Mitosis –Meoisis

14. Section 2 Cell Division Chapter 8 Cell Division in Prokaryotes

15. QOD Define mitosis. What is the end result of mitosis?

16. To return to the chapter summary click escape or close this document. Stages of Cell Cycle

17. III. The Cell Cycle  Interphase –G1 –S–S–S–S –G2  M Phase –Mitosis –Cytokinesis

18. The M phase  Mitosis – Division of the nucleus –Prophase –Metaphase –Anaphase –Telophase  Cytokinesis – Division of the cytoplasm

19. Mitosis

20. To return to the chapter summary click escape or close this document. Animal cell undergoing mitosis

21. Prophase  Nucleus disappears  Centrosomes/Centrioles move  Spindle fibers form – mitotic spindle –Kinetochore fibers/ Kinetochore –Polar fibers

22. Mitosis continues  Metaphase –Metaphase plate  Anaphase –Role of kinetochore  Telophase –Reversal of prophase –Results:

23. QOD How does the cell control the cell cycle? What happens when control is lost?

24. To return to the chapter summary click escape or close this document. Animal cell undergoing mitosis

25. To return to the chapter summary click escape or close this document. Plant Cell Undergoing Mitosis

26. Cytokinesis  Division of the cytoplasm  Separates two nuclei into two distinct daughter cells  Animal cells – cleavage  Plant cells – form cell plate

27. Control of Cell Division  Checkpoints: –G1 –G2 –Mitosis  Loss of control –Cancer

28. QOD Compare and contrast mitosis to meiosis

29. Chapter 8: Cell Reproduction Section 8-3: Meiosis

30. To return to the chapter summary click escape or close this document. Homologous Chromosome

31. Meiosis  “Reduction” division  Produces gametes  2 divisions  Diploid  haploid  Fertilaztion – n + n = 2n

32. To return to the chapter summary click escape or close this document. Meiosis Diagram

33. Meiosis I  Prophase I –Much of it same as prophase in mitosis  Nucleus/nucleolus disappears  Chromosomes coil  Centrioles and spindle fibers –Homologous chromosomes pair up  Synapsis  Forms a tetrad  Crossing-over  genetic recombination

34. To return to the chapter summary click escape or close this document. Crossing Over Diagram

35. QOD What is independent assortment?

36. Meiosis I  Metaphase I –Tetrads line up  Anaphase I –Independent assortment  genetic variation  Telophase I –Cytokinesis begins –Forms 2 haploid cells

37. LE 13-8ab Sister chromatids Chiasmata Spindle Centromere (with kinetochore) Metaphase plate Homologous chromosomes separate Sister chromatids remain attached Microtubule attached to kinetochore Tetrad MEIOSIS I: Separates homologous chromosomes PROPHASE I METAPHASE I ANAPHASE I Homologous chromosomes (red and blue) pair and exchange segments; 2n = 6 in this example Pairs of homologous chromosomes split up Tetrads line up

38. Meiosis II  No copying of DNA  Follows process of mitosis  Prophase II  Metaphase II  Anaphase II  Telophase II  Cytokinesis

39. LE 13-8b Cleavage furrow MEIOSIS II: Separates sister chromatids PROPHASE II METAPHASE IIANAPHASE II TELOPHASE I AND CYTOKINESIS TELOPHASE II AND CYTOKINESIS Sister chromatids separate Haploid daughter cells forming Two haploid cells form; chromosomes are still double During another round of cell division, the sister chromatids finally separate; four haploid daughter cells result, containing single chromosomes

40. Results  Gametes –4 haploid cells –Genetically different  Males: –Spermatogensis  Females: –Oogenesis –1 egg cell, 3 polar bodies

41. Chapter 8 Meiosis in Male and Female Animals Section 3 Meiosis