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Cell Division


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Cell Division

  1. 1. Bellringer <ul><li>How are chromotin and chromosomes different ? </li></ul><ul><li>Explain what Binary Fission is? </li></ul>
  2. 2. Agenda <ul><li>NOTES: Cell Division </li></ul><ul><ul><li>Purpose of Division </li></ul></ul><ul><ul><li>Chromatin & Chromosomes </li></ul></ul><ul><ul><li>Binary Fission (bacteria division) </li></ul></ul><ul><ul><li>Cell Cycle (eukaryotic division) </li></ul></ul><ul><ul><li>Introduction to Steps of Mitosis </li></ul></ul>
  3. 3. Why do cells divide? <ul><li>Unicellular creatures divide as a way to reproduce. Their “children” are just separated halves of the “parent”. </li></ul><ul><li>Multicellular lifeforms divide their cells in order to grow larger and to replace dead cells. Your body replaces about 300,000 cells each minute. </li></ul>
  4. 4. Parent and Daughter Cells <ul><li>Cell division creates 2 identical copies </li></ul><ul><ul><li>The cell that is divided is called the “Parent Cell” </li></ul></ul><ul><ul><li>The 2 new cells are called “Daughter Cells” </li></ul></ul>Parent Cell Two identical daughter cells
  5. 5. Daughter Cell DNA <ul><li>Remember that DNA carries all of the instructions for a cell. </li></ul><ul><li>Every daughter cell needs a complete set of its parent’s DNA. Without a full set information would be lost. </li></ul><ul><li>This means that a parent cell must create two sets of DNA before dividing so each daughter can have one. </li></ul>
  6. 6. Chromatin & Chromosomes <ul><li>DNA is usually packed loosely within the cell. DNA in this “normal” state is called chromatin. </li></ul><ul><li>Before dividing, a cell’s DNA will form large, tightly packed clumps called chromosomes. This is done to allow pieces of DNA to be easily sorted and moved around. </li></ul><ul><li>After dividing, a chromosome will loosen up and the DNA converts back into chromatin. </li></ul>
  7. 7. Chromosomes
  9. 9.
  10. 10. Cell Division in Prokaryotes
  11. 11. Prokaryotic Chromosome <ul><li>Remember that prokaryotes have no nucleus to contain DNA </li></ul><ul><li>Their DNA forms one, circular chromosome attached to the inside of the cell membrane </li></ul>
  12. 12. Cell Division in Prokaryotes <ul><li>Prokaryotes such as bacteria divide by a quick and simple process called binary fission </li></ul><ul><li>First the single chromosome makes a copy of itself </li></ul><ul><li>A cell wall then forms between the chromosomes dividing the cell </li></ul>
  13. 13. Prokaryotic Division Video
  14. 14. Eukaryotic Division: Cell Cycle <ul><li>Eukaryotic cells divide by a longer and more complex method known as the cell cycle. </li></ul><ul><li>There are 4 stages of the cell cycle. </li></ul><ul><ul><li>G 1 : First Growth </li></ul></ul><ul><ul><li>S: Synthesis Stage </li></ul></ul><ul><ul><li>G 2 : Second Growth </li></ul></ul><ul><ul><li>M: Mitosis </li></ul></ul>
  15. 15. G 1 Stage <ul><li>G 1 is the first growth stage of a newly created cell. </li></ul><ul><li>The cell matures by growing larger and creating more organelles. </li></ul><ul><li>Cell carries on its normal metabolic activities </li></ul>
  16. 16. S Stage <ul><li>S is the synthesis stage. The cell copies all of its DNA to make a second set. </li></ul><ul><li>This prepares for division at later stages </li></ul>
  17. 17. G 2 Stage <ul><li>This second growth stage occurs after DNA has been copied </li></ul><ul><li>The cell begins creating specialized organelles and structures that will do the work of dividing. </li></ul>
  18. 18. Cell Cycle Daughter Cells DNA Copied Cells Mature Cell prepares for Division Cell Divides into Identical cells
  19. 19. M stage <ul><li>Mitosis is the division process. </li></ul><ul><li>During this time DNA clumps into chromosomes and then is separated into two groups. </li></ul><ul><li>When the cell divides, each daughter receives half of the chromosomes. </li></ul>
  20. 20. 5 Stages of Mitosis <ul><li>Mitosis is divided into 5 steps that we will study in detail in future lessons. </li></ul><ul><ul><li>Prophase </li></ul></ul><ul><ul><li>Metaphase </li></ul></ul><ul><ul><li>Anaphase </li></ul></ul><ul><ul><li>Telophase </li></ul></ul><ul><ul><li>Cytokinesis </li></ul></ul>
  21. 21. Cell Cycle Summary Video