Chapter: Cell Reproduction

2. Table of Contents Chapter: Cell Reproduction Section 1: Cell Division and Mitosis Section 2: Sexual Reproductionand Meiosis Section 3: DNA

3. Cell Division and Mitosis 1 Why is cell division important? • Multicellular organisms need cell division to grow and replace dead cells • Unicellular organisms divide to reproduce

4. Cell Division and Mitosis 1

5. Cell Division and Mitosis 1 Interphase • Hereditary material copies • Organelles grow and duplicate

6. Cell Division and Mitosis 1 Mitosis • Mitosis - nucleus divides to form two identical nuclei. • Steps of mitosis - prophase, metaphase, anaphase, and telophase. • P M A T

7. Cell Division and Mitosis 1 Steps of Mitosis • Chromosome - structure in the nucleus that contains hereditary material.

8. Cell Division and Mitosis • Chromatids- 2 tightly coiled thickened, identical strands 1 Steps of Mitosis

9. Cell Division and Mitosis 1 Steps of Mitosis • Prophase • Pairs of chromatids visible • Nucleolus and nuclear membrane disintegrate • Centrioles move to opposite ends of cell • Spindle fibers form

10. Cell Division and Mitosis 1 Steps of Mitosis • Metaphase • Spindle fibers attach to centromere of chromatid • Chromatids line up across Middle

11. Cell Division and Mitosis 1 Steps of Mitosis • Anaphase • Spindle fibers shorten • Chromatids separate and move to opposite ends • Each chromatid now called a chromosome

12. Cell Division and Mitosis 1 Steps of Mitosis • Telophase • Spindle fibers start to disappear • Chromosomes start to uncoil • New nucleus forms.

13. Cell Division and Mitosis 1 Division of the Cytoplasm • After mitosis the entire cell splits • Plant cells – cell plate appears Click box to view movie.

14. Cell Division and Mitosis 1 Results of Mitosis • 2 identical nuclei • 2 cells instead of 1

15. Cell Division and Mitosis 1 Asexual Reproduction • Asexual reproduction - new organism with identical genes (sometimes more than one) is produced from one organism.

16. Cell Division and Mitosis 1 Cellular Asexual Reproduction • Fission – cells without a nucelus copy gentetic material and divide

17. Cell Division and Mitosis 1 Budding and Regeneration • Budding – bud develops and breaks away as a new organism

18. Cell Division and Mitosis 1 Budding and Regeneration • Regeneration - uses cell division to regrow body parts • Examples: sponges, planaria, seastars

19. Section Check 1 Question 1 Many-celled organisms grow by _______. Answer The answer is cell division. Cell division increases the total number of cells in an organism.

20. Section Check 1 Question 2 What is the longest part of the cell cycle?

21. Section Check 1 Answer The answer is interphase. Interphase is the period of growth and development in a eukaryotic cell.

22. Section Check 1 Question 3 _______ is the process in which the nucleus divides to form two identical nuclei. Answer The answer is mitosis. Each new nucleus that is produced is identical to the original nucleus.

23. Sexual Reproduction and Meiosis 2 Sexual Reproduction • Sexual reproduction - two sex cells come together. • Sperm - formed in testes • Eggs - formed in ovaries

24. Sexual Reproduction and Meiosis 2 Sexual Reproduction • Fertilization - joining of an egg and a sperm • Zygote – cell made when they join

25. Sexual Reproduction and Meiosis 2 Diploid Cells • Diploid - cells with pairs of similar chromosomes • Humans – 23 pairs, 46 total chromosomes

26. Sexual Reproduction and Meiosis 2 Haploid Cells • Haploid – cells that do not have pairs of chromosomes

27. Sexual Reproduction and Meiosis 2 Meiosis and Sex Cells • Meiosis - produces haploid sex cells.

28. Sexual Reproduction and Meiosis 2 Meiosis I and Meiosis II.

29. Sexual Reproduction and Meiosis 2 Meiosis I

30. Sexual Reproduction and Meiosis 2 Meiosis I • Prophase I – pairs of chromosomes come together

31. Sexual Reproduction and Meiosis 2 Meiosis I • Metaphase I - pairs of duplicated chromosomes line up in the center of the cell.

32. Sexual Reproduction and Meiosis 2 Meiosis I • Anaphase I - 2 pairs of chromatids separate

33. Sexual Reproduction and Meiosis 2 Meiosis I • Telophase I • Cytoplasm divides • 2 new cells form

34. Sexual Reproduction and Meiosis 2 Meiosis II

35. Sexual Reproduction and Meiosis 2 Meiosis II • Prophase II • Duplicated chromosomes and spindle fibers reappear

36. Sexual Reproduction and Meiosis 2 Meiosis II • Metaphase II • Duplicated chromosomes move to the middle

37. Sexual Reproduction and Meiosis 2 Meiosis II • Anaphase II • Centromere divides • Chromatids move to opposite ends of the cell.

38. Sexual Reproduction and Meiosis 2 Meiosis II • Telophase II • Spindle fibers disappear • Nuclear membranes form

39. Sexual Reproduction and Meiosis 2 Summary of Meiosis Click box to view movie.

40. Sexual Reproduction and Meiosis 2 Mistakes of Meiosis

41. Section Check 2 Question 1 _______ is the joining of an egg and a sperm. Answer The answer is fertilization. Fertilization occurs during sexual reproduction.

42. Section Check 2 Question 2 _______ and _______ are the two types of cells your body forms. A. body and sex B. egg and sperm C. meiosis and mitosis D. zygote and embryo

43. Section Check 2 Answer The answer is A. Egg cells and sperm cells are both types of sex cells.

44. Section Check 2 Question 3 Which best describes the sperm and egg?

45. Section Check 2 C. zygotes D. diploid cells A. typical body cells B. haploid cells

46. Section Check 2 Answer The answer is B. Sperm and eggs are sex cells that do not have pairs of chromosomes.

47. http://www.comedycentral.com/motherload/index.jhtml?ml_video=91511http://www.comedycentral.com/motherload/index.jhtml?ml_video=91511 What is DNA?

48. DNA 3 What is DNA? • DNA – contains the cell’s hereditary material • Found in nucleus • Passes information to offspring

49. DNA 3 DNA’s Structure • Watson & Crick (1953) made a model of a DNA molecule.

50. DNA 3 A DNA Model