The Cell Cycle

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Author:
rica_ross
ID:
227193
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The Cell Cycle
Updated:
2013-07-22 01:03:52
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Biology GRE
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Biology GRE
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  1. Mitosis: Steps
    • G1-growth 1
    • G0-Resting state
    • S- Synthesis
    • G2- Growth 2
    • Prophase
    • Metaphase
    • Anaphase
    • Telophase
  2. Interphase
    • G1-G2
    • Chromosomes are un condensed
  3. Go
    • Resting state
    • If cells are in G0 they usually remain here until they die
  4. Synthesis
    • DNA is replicated (looks like x)
    • Centrioles copy themselves and move to opposite ends of the cell
  5. Growth two
    • wants to make sure volume has actually doubled before cell division 
    • In fast dividing cells G2 is very short and cell size may remain the same
  6. Mitosis: Key points
    • Chromosomes shorten and thicken/condense in the nucleus and nuclear membrane dissolves
    • The mitotic spindle of microtubules is formed
    • The contractile ring of actin develops around the center of the cell
  7. Centrioles in cell division
    • Replicate in S and move to opposite ends of the cell
    • These centrioles form the foundation for centrosomes (Centrioles are inside them)
    • Microtubules organizing centers that shoot linked tublin across the cells
  8. Prophase
    • Chromatin shows up under microscope as well desfine chromosomes
    • Chromosomes are see as x shape
    • Two sister chromatids connect at a centromere
    • Mitotic Spindle begins for form
  9. Prometaphase
    • Nuclear membrane dissolves
    • Spindle of microtubules enter nucleus and attach to chromosomes
  10. Kintochore
    Attached microtubules to chromosomes
  11. Polar or non Kintochore Microtubules
    Non attached microtubules
  12. Metaphase
    • Kintechore microtubules push from opposite poles equally so chromosomes are at center of the cell
    • This center area, where chromosomes line up, is called the metaphase plate
  13. Anaphase
    • Paired sister chromatids separate and kintochore microtubules shorten rapidly
    • Polar microtubules lengthen pushing cells farther apart
  14. Chromatin
    Uncondensed chromosomes
  15. Telophase
    • Separated sister chromatids group together by centrosome
    • New nuclear envelope
    • Mitosis has ended
    • Chromosomes uncondense
  16. Cytokenesis
    • Contractile ring of actin fiber shorten at center of cell
    • Creates cleavage (indentaentation) at ring
    • Membrane pinches off and two cells now exist where one did before
  17. Plant Cytokensis
    • Cannot form actin ring with a cell wall
    • New cell is created within old cell vesicles filled with cell wall parts merge along a straight line at center of cell
    • As the Vesicles merge new cell wall is created  (Cell plate)
  18. Checkpoints
    Determine if cell goes to next stage of cell cycle
  19. Cyclin Dependent Protein Kinases (Cdk's)
    • Regulate cell cycle
    • Protein kinases are enzymes that add phosphate groups to phosphorylate other proteins
    • Are activated by cyclins and once active they activate other proteins to initiate next stage in cell cycle
  20. Cell Error:Polyploid
    • If a cell undergoes s phase but does not enter or complete metaphase the cell will be polyploid
    • Have two copies of DNA
  21. Cancer
    Is characterized by a loss of control over cell proliferation
  22. Four Genes Associated with Cell Division
    • Growth factors
    • Growth factor receptors
    • Intracellular signal transducing proteins
    • Nuclear transcription factors
  23. Proto-oncogenes vs oncogenes
    Normal genes vs when mutations occur that genes loose control over some aspect of growth and division
  24. Growth factors
    act on cell surface receptors causing cells to initiate growth division
  25. Density Dependent Inhibition
    Normal cells can surpress growth when near other cells
  26. Growth factor receptors
    • Membrane spanning proteins
    • Problems occur when mutation occurs and receptors increase affinity for growth factor proteins
    • Persistant activation of second messenger, leads to activate of genes involved in cell division and growth
  27. Intracellular signal transducing proteins
    • Carry signals from receptors on surface to nucleus (second messengers)
    • Turn on/off genes
    • Can increase creation/transcription of genes involved in growth divison
  28. Nuclear Transcription Factors
    • Facilitate activation of certain genes 
    • Genes involved with growth division
  29. Protective Mechanisms
    • DNA damage can turn proto-oncogenes to oncogenes
    • Sunlight UV, Viruses, x rays, toxins can lead to DNA damage
    • Pre cancerous cells call kill themselves vis apoptosis
  30. p53 protein
    • Tumor suppressor gene
    • is accumulated in cell in response to DNA damage
    • Can shut down cell cycle in G1 by activating p21 an inhibitor of cdk needed to move cell onward in cell cycle
  31. prb
    • Tumor suppressor gene
    • appears to inhibite e2f crucial for cells moving fromG1-->s
    • Deffective prb causes rapid change in G1-->S

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