The Cell Cycle

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The Cell Cycle

• A cell quest

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I. Cell Cycle Purpose

• A. The cell cycle is the cycle a cell goes
  through in order to make additional cells.
• Growth
• Replacing dead/worn-out cells
• Healing wounds
• B. The Stages of the cell cycle are
• G1 (Gap 1)
• S (Synthesis)
• G2 (Gap 2)
• M (Mitosis)
• Cytokinesis

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II. DNA Packing
Tightly coiled DNA contains genetic information
Two identical parts of a chromosome sister
chromatids
Holds sister chromatids together at the center
Chromatin
Loosely coiled DNA wrapped around histones
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Cell Cycle Wheel
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III. Interphase

• G1, S, and G2 are all part of interphase.
• G1- During G1 the cell grows in size and collects
  all the enzymes needed for Synthesis.
• S- During Synthesis genetic information inside of
  the cell doubles to create two sets of identical
  chromosomes. DNA replication
• So if a cell normally has 23 pairs of chromosomes
  (like us!) after S-phase it has 46 pairs.
• G2- In G2, the cell produces microtubules, which
  are needed for mitosis

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III. Interphase
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IV. Mitosis

• Mitosis is the division of one mother cell into
  two identical daughter cells.
• The phases of mitosis are prophase, metaphase,
  anaphase, and telophase.

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A. Prophase

1. Spindle Fibers form
2. Centrioles move to opposite poles
3. Chromosomes become visible

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B. Metaphase

1. Chromosomes line up along the equator

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C. Anaphase

1. Chromosomes divide
2. Chromatids seperate and move to opposite poles

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D. Telophase

• Nuclear membrane forms around each group of
  chromosomes
• Chromosomes unwind
• Cytokinesis begins

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V. Cytokinesis

• The process by which the cytoplasm divides and
  one cell becomes two individual cells. The
  process is different in plants and animals

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V. Cytokinesis

• Animals - cell membrane pinches inward
• Plants - a new cell wall forms between the two
  new cells

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Cell Cycle Wheel
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VI. What stops cell from growing?

• Touching neighbor cells.
• Cells in a petri dish will continue to grow until
  they come into contact with other cells.
• Similarily, skin around a wound stops to grow
  when it contacts other skin cells
  
  

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Which chemicals regulate the cell cycle?

• A protein called cyclin regulates the timing of
  the cell cycle and causes cells to divide.

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How do cells respond to contact with other cells?

• Normally, cells stop growing when they come into
  contact with other cells

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VII. How are cancer cells different from other
cells?

• Cancer cells do not respond to cyclins that
  regulate the growth of most cells.
• Cells divide uncontrollably and form masses of
  cells called tumors
• The disease cancer results from these cells not
  performing their normal jobs
• Thought to be caused by a mutation on gene p53
• p53 blocks cell maturation in damaged cells.
• apoptosis

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Lung Cancer
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Oral cancer (tobacco chewing)
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Cancer Treatment

• Surgery to remove cancer
• Chemotherapy
• Radiation
• Viral Vector