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The Cell Cycle

The Cell Cycle

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The Cell Cycle

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  1. The Cell Cycle

  2. 1/27/12 • Objective: Understanding the components of the cell cycle • Do now: Do the hokey pokey, turn yourself around. • Do later: Draw a cell going through the four phases of mitosis, and label the major events in each phase.

  3. Quiz time! • On a sheet of paper, define (8 words or less!) • Mitosis • Cytokinesis • Stem Cell • Apoptosis

  4. Cell Theory • All cells arise from the division of older cells • Mitosis!

  5. Cell cycle • Short version: • Cell grows, divides, forms two new cells • Long version: • Much more detailed…

  6. Cell Cycle • First phase: G1 • Growth phase 1 • Cell grows in size and increases its supply of organelles

  7. Cell Cycle • First phase: G1 • Most of a cell’s life is spent in G1 • End of G1: Checkpoint • Proceed to division? • Die?

  8. Cell Cycle • Second phase: S • Synthesis of DNA • Cell copies its DNA so that there is enough for two new cells.

  9. How much DNA do we have? Full complement of DNA 46 chromosomes

  10. DNA Replication What is the difference between these two pictures? Can you explain the difference?

  11. DNA Replication • DNA is a double helix • Complementary base pairs • Helicase unzips DNA • DNA polymerase creates a complement for each strand

  12. Cell Cycle • Third phase: G2 • Cell continues to grow • Produces all the components necessary to form two complete cells

  13. Cell Cycle • G1 + S + G2= Interphase • Interphase = when the cell is growing and preparing for cell division

  14. Cell Cycle • Fourth phase: Mitosis • Cell divides into two daughter cells • Each has one full set of DNA • 4 phases • Prophase • Metaphase • Anaphase • Telophase

  15. Mitosis • Prophase • DNA condenses into chromosomes • Nucleus disintegrates • Spindle apparatus forms

  16. Mitosis • Spindle apparatus • Microtubules extend out from the centrosomes and attach to each doubled chromosome • Organizes and pulls apart doubled chromosomes to ensure a full set of DNA in each daughter cell.

  17. Mitosis • Metaphase • Doubled chromosomes line up in the center of the cell

  18. Mitosis • Anaphase • Doubled chromosomes break apart • 1 copy of each chromosome goes to each side of the dividing cell

  19. Mitosis • Telophase • Prophase in reverse • Spindle apparatus disintegrates • Nuclei re-form • Chromosomes unwind

  20. Quiz time! • Which phase of mitosis is represented in this picture?

  21. Quiz time! • Which phase of mitosis is represented in this picture?

  22. Quiz time! • Which phase of mitosis is represented in this picture?

  23. Quiz time! • Which phase of mitosis is represented in this picture?

  24. Cytokinesis • Cytokinesis • Division of the cytoplasm to form two new cells