1. Cell Division

2.   The process of a cell dividing into two identical daughter cells.

3. Background Info   DNA – the molecule that carries genetic information   Chromosomes – condensed DNA   Chromatin – DNA that is uncondensed & thread-like

4. Chromosome vs. Chromatin

5. Background Info   Chromatids – the two identical “sister” parts of a chromosome   Centromere – where the two chromatids attach

6.   The cells of every organism have a specific number of chromosomes.   Fruit Flies8 chromosomes   Humans46 chromosomes   Carrots18 chromosomes   Hedgehogs90 chromosomes

7. The Cell Cycle : The events a cell goes through as it grows and divides.

8. Two main phases  Interphase – The time a cell spends not dividing. A cell spends the majority of its life in this phase.  M-phase – When the cell divides.

9. Interphase  G1 –The cell doing its normal functions.  The cell grows  Protein synthesis  Mitochondria/Chloroplasts made  Other organelles made  S (synthesis) phase - new DNA is made.  G2 – The cell gets ready for mitosis.

10. M phase  Mitosis – the first stage of cell division, where the nucleus divides.  Cytokinesis – the second stage of cell division, where the cytoplasm divides.

11. Length of cell cycle  How often a cell divides depends on the particular function of the cell.  Bacterial cells30 minutes  Skin cells12 hours  Liver cells2 years  Muscle cellsnever

12. Regulating the Cell Cycle   A protein called, cyclin, regulates the timing of the cell cycle.

13. When things go wrong   Cancer happens when cells lose the ability to regulate the cell cycle.   Cancer cells divide uncontrollably.   Cancer cells form masses of cells called tumors.   Cancer cells can occur in any type of tissue.

14. Example of Normal Growth Cell migration Dermis Dividing cells in basal layer Dead cells shed from outer surface Epidermis

15. Tumors (Neoplasms) Underlying tissue

16. Mitosis

17. Animated Mitosis Cycle http://www.cellsalive.com/mitosis.htm Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

18. Interphase Prophase Metaphase Anaphase Telophase & Cytokinesis

19. Interphase

20. Interphase occurs before mitosis begins Regular cell activity Regular cell activity Its not an inactive phase, but a phase when a lot of metabolic reactions occur. Its not an inactive phase, but a phase when a lot of metabolic reactions occur. Chromosomes cannot be seen. Chromosomes cannot be seen. CELL MEMBRANE Nucleus Cytoplasm

21. Interphase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

22. Mitosis  The division of somatic or regular cells.  It’s divided into 4 phases.  Remember Interphase is NOT part of Mitosis.

23. Mitosis 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase

24. Prophase 1 st step in Mitosis Nuclear membrane breaks down. Nuclear membrane breaks down. Chromosomes become visible Chromosomes become visible Centrioles appear and move to opposite ends of the cell. Centrioles appear and move to opposite ends of the cell. Chromosomes attach to Spindle fibers. Chromosomes attach to Spindle fibers. Centrioles Sister chromatids Spindle fibers

25. Prophase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm Spindle fibers Centriole

26. Metaphase 2 nd step in Mitosis Chromosomes line up in the center of the cell. Chromosomes line up in the center of the cell. Spindle fibers (microtubules) attach to the centromeres. Spindle fibers (microtubules) attach to the centromeres. Centrioles Spindle fibers

27. Metaphase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

28. Anaphase 3 rd step in Mitosis Spindle fibers contract and pull apart sister chromatids. Spindle fibers contract and pull apart sister chromatids. Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Chromatids (or pairs of chromosomes) separate and begin to move to opposite ends of the cell. Centrioles Spindle fibers

29. Anaphase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

30. Telophase 4th s tep in Mitosis Chromosomes gather at the opposite ends of the cell. Chromosomes gather at the opposite ends of the cell. Nuclear membranes reform around each cluster of chromosomes (2 new nuclei). Nuclear membranes reform around each cluster of chromosomes (2 new nuclei). Chromosomes turn into chromatin (threads). Chromosomes turn into chromatin (threads). Mitosis ends. Mitosis ends.

31. Telophase Animal Cell Plant Cell Photographs from: http://www.bioweb.uncc.edu/biol1110/Stages.htm

32. Cytokinesis occurs after mitosis Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. Cell membrane moves inward to create two daughter cells – each with its own nucleus with identical chromosomes. The two cells are identical to the original and to each other. The two cells are identical to the original and to each other.

33. Cytokinesis  In plant cells, a cell plate forms down the center.  In animal cells, new membrane is formed.

34. Animal Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

35. Plant Mitosis -- Review Interphase Prophase Metaphase Anaphase Telophase Interphase

36. REMEMBER! Prophase Metaphase Anaphase Telophase Cytokinesis IPMATC I Pray M ore At T he Church

37. 37 Cell Cycle

38. Mitosis

39. Onion Root Lab - Mitosis

40. Interphase Prophase Anaphase Metaphase Telophase Cytokinesis

41. Interphase Prophase Metaphase AnaphaseTelophase

42. What processes involve mitosis? 1.Growth 2.Embryonic Development 3.Tissue Repair 4.Asexual Reproduction

43. Self- Quiz p. 234 #s 2,4,7,9,10,11

44. Copyright Pearson Prentice Hall The series of events that cells go through as they grow and divide is called a.the cell cycle. b.mitosis. c.interphase. d.cytokinesis.

45. Copyright Pearson Prentice Hall The phase of mitosis during which the chromosomes line up across the center of the cell is a.prophase. b.metaphase. c.anaphase. d.telophase.

46. Copyright Pearson Prentice Hall Cytokinesis usually occurs a.at the same time as telophase. b.after telophase. c.during interphase. d.during anaphase

47. Copyright Pearson Prentice Hall DNA replication takes place during the a.S phase of the cell cycle. b.G 1 phase of the cell cycle. c.G 2 phase of the cell cycle. d.M phase of the cell cycle.

48. Copyright Pearson Prentice Hall During mitosis, “sister” chromatids separate from one another during a.telophase. b.interphase. c.anaphase. d.metaphase.

49. Copyright Pearson Prentice Hall 6 The cell cycle is believed to be controlled by proteins called a.spindles. b.cyclins. c.regulators. d.centrosomes.