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Cell Reproduction Mitosis Meiosis Creates 2 identical cells Creates 4 different cells Creates body cells Body cells, Skin Cells, Tissues, Organs Creates sex cells Sperm and egg 2 Diploid cells = 2n or 2 sets of chromosomes Haploid cells = 1n or 1 set of chromosomes

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____________________ Increase in number of cells. Replace worn out or damaged cells. 3

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1. Gap 1: Cell Growth 2. Synthesis: DNA Replication 3. Gap 2: Preparation of Mitosis 4. Mitosis Interphase A long period of cell growth 5

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G1 Phase: The cell grows in size. S Phase: DNA # is doubled. G2 Phase: gets ready for mitosis. Develops its organelles. Checkpoint 1 *Has 2 complete sets of DNA Checkpoint 2 6

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G1 phase: Cell Growth S phase: DNA Replication 7

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1 Chromosome = 1 chromatid 8 Duplicated Chromosome = Sister chromatids

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Condensed, duplicated chromosome or sister chromatids chromatid centromere Holds the duplicated chromosome together G2 phase: Cell gets ready for mitosis 9 Chromatid

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Centrioles copies are made 1. More cytoplasm- cell grows. 2. DNA is being replicated. 3. More organelles The cell is getting ready for MITOSIS, cell division. ***DNA is in the form of Chromatin (ball of DNA) 10

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Prophase Metaphase Anaphase Telophase _______________________________________ 11

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X X X X 2. Nuclear Membrane Breaks down 3. Centrioles move apart. 1.Chromatin forms visible chromosomes 4. Fibers form 12

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1. DNA2. Nuclear Membrane 3. Centrioles4. Fibers Chromatin condenses into visible chromosomes Begins to break down Move apart from one another in opposite directions Form between centrioles 13

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XX XX 4.THE NUCLEAR MEMBRANE IS NO LONGER PRESENT 2. Spindle fibers connect to the sister chromatids 3. Sister chromatids are lined up along the middle of the cell. 1. Centrioles move to opposite poles. 14

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1. Centrioles2. Fibers3. DNA4. Nuclear Membrane Continue to move to opposite ends of the cell Is completely gone Sister chromatids are pulled to the middle of the cell 15 Attach to the sister chromatids.

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> > > > > > > > 2.Centrioles begin to pull the chromosomes toward the opposite sides of the cell. 1. Sister Chromatids separate 16

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1.Sister Chromatids 2.Fibers3.Centrioles4.Nuclear Membrane Pulled apart Each chromatid is separate from its sister Still at opposite sides of the cell Pull each chromatid toward opposite ends of cell Is still gone 17

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>> > > > > > > 3.Cell Membrane pinches at center 2. Nuclear Membrane begins to reappear 4. Fibers begin to disappear 1.Chromosomes are at opposite sides of the cell 18

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1.Sister Chromatids 2.Nuclear Membrane 3.Cell Membrane 4.Fibers Each end of cell has a complete set of chromosomes. Begins to reform around the sets of chromosomes Begins to pinch at the center, forming two new identical cells Begin to disappear 19

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Cell Membrane splits into two new identical cells 20

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Phases of Mitosis: Prophase Metaphase Anaphase Telophase 22

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Another Animation of Mitosis Cell Cycle of Mitosis Control of the cell cycle Interactive review of mitosis from Classzone.com Video clips 23

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The process is VERY SIMILAR in each type of cell. There are only 2 differences: 1.Plant cells do not have centrioles 2.The cell membrane cannot pinch because of the cell wall. 3.Instead a cell plate forms between the 2 nuclei division. 24

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External factors Physical signal cell to cell contact. Once a cell touches another cell it stops dividing. When cells fail to respond to the external signal, the cells continue to divide uncontrollably and form clumps. Tumor is a clump of cancer cells. Benign tumor is harmless, the cells are clustered together tightly and can be removed. Malignant tumor is bad, the cells can break away and be carried to other parts of the body. When a tumor has metastasized, it means the cancer cells have spread to other parts of the body. 26

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Cancer cells do not perform the specialized functions needed by the body. In the lung cancer cells do not exchange oxygen and carbon dioxide. In the brain they do not transmit the messages needed to interpret information to the body Can exert great pressure on surrounding organs. 27

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Carcinogen a substance known to produce or promote the development of cancer cells. 28

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cancer cell bloodstream normal cell 29

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Cuts chromosome number in half. Creates haploid cells. Creates sperm and egg Spermatogenesis the creation of sperm Oogenesis the creation of ova (egg) 30

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Sperm or Eggs In males: These cells develop into 4 individual sperm that are genetically different from the parent cell. In females: These cells would have developed into 3 small polar bodies which will die and only 1 large egg. (THIS IS DUE TO AN UNEVEN DIVISION OF CYTOPLASM DURING MEIOSIS) 31

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Fertilization: Union of sperm and Egg Creates a zygote Re-establishes the full number of chromosomes 2 chromosomes 4 chromosomes 32

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For growth and to replace old, worn out cells. Occurs in body cells Two cells from 1 cell Identical cells to the parent cell. Same number of chromosomes as the original (2N) - diploid One division of the nucleus. To make sperm and eggs with Occurs in sex cells Four cells from 1 cell Genetically different from the parent cell. Half the number of chromosomes (1N) - haploid Two divisions of the nucleus. 33

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