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Mitosis

Mitosis. Where it all began……. You started off as a cell smaller than the period at the end of a sentence………. And now look at you! . How do you get from being smaller than a “period” to a growing human being?. Getting from here to there. Going from egg to baby….

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Mitosis

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  1. Mitosis

  2. Where it all began……. You started off as a cell smaller than the period at the end of a sentence………

  3. And now look at you! How do you get from being smaller than a “period” to a growing human being?

  4. Getting from here to there Going from egg to baby…. the original fertilized egg has to divide… and divide… and divide… and divide…

  5. Why do cells divide? • Growth • From fertilized egg to multicellular organism • Repair • Replace cells from normal wear and tear and injury • Reproduction • Asexual Reproduction (1 celled organisms)

  6. What is the Cell cycle? • The cell cycle is the process by which the cell grows and divides to make copies of itself • The life of a cell is divided into 2 stages: • Mitosis (Division of nuclear material) • Cytokinesis (Division of cytoplasm and organelles)

  7. Cells in Interphase for about 90% of their life Your cell muscles are constantly breaking apart and being replaced, the cells in your small intestine are constantly absorbing nutrients and cells are always dividing. A cell doing its “everyday job” as well by making proteins, enzymes and etc… Interphase

  8. DNA REPLICATION • We know that DNA can replicate by “unzipping”, and then rejoining itself • When it creates a copy of itself, the copy is called the sister Chromatids

  9. Mitosis • There are 5 parts (four steps) in Mitosis. • 1 Interphase, 2 Prophase, 3 Metaphase, 4 Anaphase, 5 Telophase (and here is where the sister cell is found) Nucleus Cytokinesis starts Chromosome Spindle Fibre 1 2 3 4 5

  10. Prophase Chromosomes coil up into an X-Shaped chromosome Spindle Fibers form and stretch across the centrioles at opposite ends of the cell Chromosomes attach to spindle fibers at their centromeres Nucleolus disappears and the nuclear membrane breaks down

  11. Prophase Centrioles (a part of the cell): Produce spindle fibers, and help organize the spindle fibers during cell division Spindle Fibers : Attach to the centromeres and direct the process of cell division Centromere : Hold the sister chromatids together

  12. Spindle fibers Plasma Membrane Centrioles Centromere Nuclear membrane Sister Chromatids

  13. Metaphase Spindle fibers pull chromosomes towards the middle of the cell The Chromosomes line up across the middle and prepare to split

  14. Anaphase 1 chromosome 2 sister chromatids Double Stranded 2 chromosomes Single Stranded Sister Chromosomes separate at the centromeres Spindle fibers pull the sister chromatids to the opposite side of the cell

  15. Telophase Spindle fibers disappear Nuclear Membrane forms around each set of chromosomes A nucleolus appears in each nucleus No there are two nuclei in one (1) cell

  16. Cytokinesis This process is what starts the Mitosis process. The cell membrane pinches together to divide the cells cytoplasm and organelles. The two nuclei are separated into 2 new daughter cells New daughter cells are identical to parent cell

  17. Mitosis Chromosomes line up at the Equator Sister Chromosomes separate and are pulled to the opposite sides of the cell Cytoplasm divides and two new daughter cells are formed that are genetically identical to the parent cell

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