1. Mitosis/Meiosis How do your cells divide?

2. A few words before we start…..  Haploid:  Diploid:

3. A Cell’s Life

4. Why Do Cells Divide? Surface area Damaged cells Sex cells

5. Cell Reproduction is either sexual or asexual

6. Asexual Reproduction (one parent)  Binary Fission-  Budding  Vegetative Propagation  Regeneration

7. Advantages of Asexual Reproduction Speed Desirable Characteristics Replacement

8. DNA Replication  Before a cell can divide the DNA must replicate (make a copy of itself)

9. DNA Replication  Making a new strand of DNA is actually quite easy.  Replication occurs in 3 easy steps…

10. 1. DNA Unzips  An enzyme unzips the molecule  The enzymes breaks the hydrogen bonds that hold the nitrogen bases together.

11. A G G T C C DNA Replication DNA Unzips

12. A G G T C C

13. A G G T C C

14. A G G T C C

15. A G G T C C

16. A G G T C C Left Strand of Original DNA Right Strand of Original DNA

17. 2. Base Pairing  Complementary bases match with each DNA strand in the open helix

18. A G G T C C Left Strand Original DNA Right Strand Original DNA DNA Replication Base Pairing

19. A G G TT C C Left Strand Original DNA Right Strand Original DNA New Right DNA Strand DNA Replication Base Pairing

20. A G G T C T C C Left Strand Original DNA Right Strand Original DNA New Right DNA Strand DNA Replication Base Pairing

21. Left Strand Original DNA Right Strand Original DNA New Right DNA Strand A G G T C C T C C DNA Replication Base Pairing

22. Left Strand Original DNA Right Strand Original DNA New Right DNA Strand A G G T C C T C C A New Left DNA Strand DNA Replication Base Pairing

23. Left Strand Original DNA Right Strand Original DNA New Right DNA Strand New Left DNA Strand A G G T C C T C C A G DNA Replication Base Pairing

24. Left Strand Original DNA Right Strand Original DNA New Right DNA Strand New Left DNA Strand A G G T C C T C C A G G DNA Replication Base Pairing

25. 3. DNA Zips Up  An enzyme zips the new molecules back up.

26. DNA Replication  Voila!  Two identical strands of DNA! T C C A G G T C C A G G T C C A G G

27. DNA Replication Review Step 1 Step 2 Step 3

28. Remember - All this takes place in INTERPHASE G2G2

29. Now that DNA has replicated, we are ready to begin Mitosis (nucleus of the cell divides) T C C A G G T C C A G G

30. Parent Cell DNA condenses into chromosomes Chromosomes align on the equator Chromosomes separate DNA uncoils

31. Cytokinesis  Cleavage (indention in cell membrane) or cell plate formation occurs.  Cell divides. Animal Cell Plant Cell

32. Mitosis Animation

33. It’s all about the chromosomes! –There are 46 in human body cells –The number of chromosomes remain constant during Mitosis

34. Which Cells Go Through Mitosis? Growth Repair Work Cells which help the body in:

35. Mitosis Review 1. Is the beginning parent cell diploid or haploid (2n or n)? 2. Are the daughter cells diploid or haploid (2n or n)?

36. More Mitosis Review 3. How many daughter cells are produced? 4. Are the resulting daughter cells different from the parent cell?

37. More Mitosis Review 5. Are the resulting daughter cells different from each other? 6. How many chromosomes are in a human parent cell? 7. How many chromosomes are in a human daughter cell?

38. More Mitosis Review 8.What types of cells are produced by mitosis? 9. Why (when) does a cell go through mitosis?

39. Meiosis Sexual Reproduction (two parents)

40. Why Meiosis?  Meiosis -

42. How does Meiosis Occur?

43. Crossing Over  What is happening?  How does this affect the individual (offspring)?

44. Crossing Over

45. Meiosis Review  Is the beginning parent cell diploid or haploid (2n or n)? 2. Are the resulting daughter cells diploid or haploid (2n or n)?

46. More Meiosis Review 3. How many daughter cells are produced?  Are the resulting daughter cells different from the parent cell?

47. More Meiosis Review 5. Are the resulting daughter cells different from each other? 7. How many chromosomes are in a human daughter cell? 6. How many chromosomes are in a human parent cell?

48. More Meiosis Review 8. What types of cells are produced by meiosis?

49. Fertilization New Individual 46 Mom 23 Dad 23

50. This is how new organisms are made!!

51. Let’s review Mitosis & Meiosis

53. Mitosis vs. Meiosis EventMitosisMeiosis Produces 4 cells Produces 2 cells New cells identical New cells different New cells have the same number of chromosomes as parent New cells have fewer chromosomes than parent √ √ √ √ √ √

54. Mitosis vs. Meiosis EventMitosisMeiosis Beginning cells diploid (2n) Beginning cells haploid (n) Ending cells diploid (2n) Ending cells haploid (n) Produces egg and sperm Produces body cells √ √ √ √ √ √