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2. 2 Unit Goals cell cycleDescribe the phases of the cell cycle. MitosisDescribe the process of Mitosis. –Describe the functions of mitosis. MeiosisDescribe the process of Meiosis. –Describe the functions of meiosis. –Explain the consequences of mistakes. 1

3. 3 Cell Size Why not just one large cell? Difficult to get nutrients in and waste out 2

4. 4 Phases of The Cell Cycle 3 G1,S, and G2 are known together as Interphase.

5. 5 2 types of cells in your body Somatic cells -Are ”Regular” Body cells -2 copies of all chromosomes (diploid) Gametes -Are sex cells -sperm and egg -1 copy of all chromosomes (haploid) 4

6. G 1 PHASE 6 5 Gap phase, cell undergoes growth

7. 7 S Phase Chromosomes Condense Chromosomes are inherited genetic information Chromosomes are made up of DNA Can only be seen when cells are dividing 6

8. 8 Chromosomes replicate- or copy is madeChromosomes replicate- or copy is made The two copies are:The two copies are: –attached together at a point called a centromere. –are called sister chromatid. When a cell divides, its two daughter cells must receive the required number of DNA molecules.

9. 9 8 sister chromatid

10. 10 G2 Phase Organelles must be replicated (copied) 9 9

11. 11 G1,S, and G2 are known together as Interphase.

12. 12 M Phase Two parts: 1.Nuclear division –Mitosis 2.Cytoplasmic Division –Cytokinesis 10 Review of Cell Cycle Clip

13. 13Mitosis Nuclear Division. –Nucleus divides into two new nuclei Mitosis keeps the number of chromosomes constant from one cell generation to the next. In eukaryotes, it is the main process by which growth and tissue repair is accomplished. –Mitosis is also the main process by which single-celled and many multi-celled eukaryotes reproduce asexually. 11

14. 14 4 Steps of Mitosis (PMAT) Prophase: Chromosomes condense and attach to the spindle fibers at their centromere. Nuclear Membrane breaks down. 12

15. 15 Steps of Mitosis (PMAT) Prophase: Centrioles move to opposite sides of the cell and organize the spindle fibers Prophase: Centrioles move to opposite sides of the cell and organize the spindle fibers 13

16. 16 Metaphase: Metaphase: Chromosomes attach to spindle fibers and line up in the middle of the cell 14

17. 17 Anaphase: Chromosomes separate- Move to opposite sides of the cell 15

18. 18 Telophase Nuclear Envelope reforms There are now TWO nuclei in one cell! 16 …And they contain the SAME genetic information *SAME NUMBER OF CHROMOSOMES

19. 19 17 Mitosis Clip

20. 20 18

21. 21 Cytokinesis Cytoplasmic divisionCytoplasmic division Each cell gets half of the organelles.Each cell gets half of the organelles. After mitosis: cell pinches in half to form two new cells.After mitosis: cell pinches in half to form two new cells. 19

22. 22Cytokinesis Animal cells pinch.Animal cells pinch. Cytokinesis in plant cells is different from that in animal cells.Cytokinesis in plant cells is different from that in animal cells. 20

23. 23 In plant cells a cell plate forms from the inside out. 21

24. 24 23

25. 25 TwoTwo new cells. called daughter cells- same number of chromosomesThe new cells- called daughter cells- have the same number of chromosomes as the mother cell. Results of Mitosis and Cytokinesis 24

26. 26 Results of Mitosis and Cytokinesis This occurs in all somatic cells in your body. You have 46 chromosomes in all of your somatic cells-23 pair! 24

27. 27 Mitosis in Onion 25

28. 28 Cells during Mitosis 26

29. 29 27

30. 30 28 https://www.youtube.com/watch?v=VlN7K1- 9QB0&feature=related

31. 31 29 includes is divided into Concept Map Cell Cycle M phase (Mitosis) Interphase G 1 phase S phase ProphaseG 2 phaseMetaphaseTelophaseAnaphase Animation

32. 32 Meiosis Meiosis Reproduction of Sex Cells Sex cells- Sperm and egg Process is called Meiosis Similar to Mitosis 30

33. 33Meiosis Cell divides twiceCell divides twice First division is like mitosis and then the cell divides again to create 4 haploid cells.First division is like mitosis and then the cell divides again to create 4 haploid cells. Not genetically identical! Contains ½ (HAPLOID) of the genetic information. DIPLOID= 2 copies) 31

34. 34 Not genetically identical! Contains ½ of the genetic information. 31.2

35. 35 MEIOSIS=CHROMOSOME REDUCTION DIVISION 32 Not genetically identical! Contains ½ of the genetic information.

36. 36Meiosis Meiosis is also know as chromosome reduction division. In Humans, starts with 46 and ends up with 23. Why? Fertilization creates the diploid condition again Diploid Haploid 34

37. 37 Sperm formationSperm formation- 4 haploid sperm cells are formed. Egg formationEgg formation-most of the cytoplasm is used in one cell and the other three disintegrate. One haploid egg cell is formed. 35

38. 38 Meiosis Video Clip 36

39. 39 Crossing Over Sometime during meiosis the chromosomes can exchange information This is called Crossing Over Major source of genetic diversity in the species 37

40. 40 38

41. 41 Nondisjunction The failure of sister chromatid pairs to separate properly during meiosis If this is the 21 st pair, it causes Down Syndrome.

42. 42 Prokaryotic Cells Binary fission Occurs in Prokaryotic Cells DNA is copied and then the cell splits in half. 39

43. 43 Regulation of the Cell Cycle How do cells know when to divide? When to stop dividing? Cyclins-proteins that regulate the cell cycle. 40

44. 44 Cancer Unregulated cell growth. Can form masses of cells called tumors. 41

45. 45 REVIEW CLIP