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

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

4 Somatic cell cycle G1 phase- Gap phase, cell undergoes growth. S phase- DNA synthesis G2 phase- Gap phase. Preparation for Mitosis. Organelles are produced. M phase- Cell division (Mitosis and cytokinesis) Interphase Regular Cells Sex cells are called gametes 4

5 G 1 Phase Cell growsCell grows 5

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

7 Chromosomes replicate-or copy is madeChromosomes replicate-or copy is made The two copies areThe two copies are -attached together at a point called a centromere. -attached together at a point called a centromere. -are called sister chromatid. -are called sister chromatid. 7

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

10 M Phase Two parts: 1.Nuclear division –Mitosis 2.Cytoplasmic Division –Cytokinesis 10

11Mitosis 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

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

13 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

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

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

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

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19 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

20Cytokinesis 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

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

22 Mitosis review video clip with quiz! Mitosis review video clip with quiz! 22

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24 Results of Mitosis and Cytokinesis Two new cells. called daughter cells-The new cells- called daughter cells- have the same number of chromosomes as the mother cell. This occurs in all somatic cells in your body. You have 46 chromosomes in all of your somatic cells-23 pair! 24

25 Mitosis in Onion 25

26 Cells during Mitosis 26

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

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

31 Meiosis 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. 31

32 MEIOSIS=CHROMOSOME REDUCTION DIVISION 32

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

35 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

36 Meiosis Video Clip 36

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

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

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

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