Cell Division/Mitosis

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Honors Biology class PPt on the process of mitosis; used following DNA

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  • G1 (G=gap): cell increases its supply of proteins and organelles and grows larger, begins after cell division; the chromosomes are singleS: DNA synthesis (replication) occurs, 1 chromosome becomes sister chromatids (In S, DNA replication results in duplicate chromosomes, one chromosome with two sister chromatids. Sister chromatids are held together by the centromere)G2: synthesis of proteins critical to cell division, leads into mitotic phase
  • AD: keeps cells from replicating where they shouldn’t (tumor)DDI: if a space opens, they will fill it in (ex. Healing a cut)
  • Cell Division/Mitosis

    1. 1. Cell Division<br />
    2. 2. Cellular Reproduction<br /> Organism’s life begins as one cell<br />Rudolf Virchow (1858) stated: All cells come from cells<br /> Prokaryotes divide only to reproduce<br />Asexual repro: 1 parent  2 daughters<br />AKA Binary fission (“dividing in half”)<br />One set of DNA duplicates, cell divides<br />
    3. 3. Eukaryotic cells divide for reproduction, growth, and replacement of cells<br /> Other organisms (plants & animals especially) reproduce through sexual reproduction<br /> Sperm + Egg <br /> offspring<br /> Offspring gets two <br /> sets of genetic <br /> information, one <br /> from each parent<br />
    4. 4. The Chromosome<br />DNA is contained in structures called chromosomes within the nucleus of the cell<br /> “chroma” color, “soma” body<br /> Most of the time, chromatin fills the nucleus<br />Tangled mass of fibers of DNA & protein <br /> When a cell begins to divide, the chromatin condenses and coils into chromosomes<br />Each chromosome has one long DNA molecule containing thousands of genes<br />
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    6. 6. The Chromosome<br />Before a cell divides, it must duplicate its chromosomes<br /> DNA replication!<br /> Once duplicated, the chromosomes have sister chromatids with identical genes, joined at a centromere<br /> When the cell divides, half goes to each daughter cell<br />
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    8. 8. The Cell Cycle<br />Sequence of events from the time a cell divides to when it forms two daughter cells<br /> Serves to double the cell’s parts, then splits<br /> Stages: <br />Interphase 90%<br />Mitotic phase 10%<br />
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    10. 10. Mitotic Phase<br />Unique to eukaryotes<br /> Ends with 2 identical cells<br /> Sub-stages of Mitosis: <br />Prophase<br />Metaphase<br />Anaphase<br />Telophase<br />Cytokenisis<br />
    11. 11. Prophase<br /> Sister chromatids are attached at centromere<br />Centrioles separate and extend spindle fibers<br /> Nucleolus disappears and nuclear envelope breaks down<br />Kinetochores form on each chromatid, spindle fibers attach<br />
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    14. 14. Metaphase<br />Centrosomes at poles<br /> Chromosomes lined up at metaphase plate (cell’s equator)<br />Kinetochores of sister chromatids face opposite poles<br />
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    16. 16. Anaphase<br /> Spindle fibers pull sister chromatids apart forming daughter chromosomes<br /> Chromosomes move centromere first towards opposite poles<br /> Cell elongates<br />
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    18. 18. Telophase & Cytokenisis<br /> Cell continues to elongate<br /> Daughter nuclei appear at poles<br /> Nuclear envelopes reform<br /> Spindle fibers disappear<br />Cytoplasms separate, new cell membranes form<br />
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    20. 20. Cytokenisis<br /> Cell pinches into two cells <br /> Called a cleavage furrow<br /> Plants are a little different<br /> Vesicles save materials from cell wall<br /> Form a plate at center of dividing cell<br /> Cell plate fuses to cell wall, 2 cells<br />
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    27. 27. Factors that Affect Cell Division<br /> Most reasons are unknown <br />“Growth Factors”<br /> Proteins need for division; if not present it stops<br /> Cell-cycle control system<br /> A system of proteins in the cell that trigger & coordinates major events in the cell cycle<br /> Make checkpoints<br />
    28. 28. Factors that Affect Cell Division<br /> Anchorage dependence<br /> Cells must be in contact with a solid surface<br /> Density-dependant inhibition<br /> Division will slow as the population grows more dense<br />
    29. 29. When It All Goes Wrong<br /> Cell-cycle control system malfunctions<br /> Cells divide excessively and in the wrong places; creates tumors<br /> Benign: normal cells<br /> Malignant: cancerous, invasive<br /> Will divide indefinitely if not treated<br />
    30. 30. When It All Goes Wrong<br /> Types of Cancers<br /> Carcinoma<br /> Skin, stomach lining<br /> Sarcoma<br /> Supporting tissues, bones<br /> Leukemia & Lymphoma<br /> Blood producing tissues, bone marrow<br /> Treatments <br /> Aim to stop the spread of cancerous cells by stopping division<br /> Chemotherapy (meds) and/or Radiation<br />

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