Controlled cell growth occurs in a petri dish containing nutrient broth'

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Controls on Cell Growth continued

• Controlled cell growth occurs in a petri dish
  containing nutrient broth.
• The cells grow until they come into contact with
  each other.

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Uncontrolled Cell Growth

• Cancer is a disorder where cells lose their
  ability to control their own rate of growth.
• When placed in a culture of living tissue,
  cancer cells will not stop growing when they
  come into contact with other cells.
• They continue to grow until the nutrient supply
  is used up.

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The Cell Cycle

• During a cell cycle, the cell grows, prepares for
  division, and divides to form 2 daughter cells.
• A single turn of the cycle is the time required
  for a cell to reproduce itself.
• The cell cycle includes interphase, mitosis, and
  cytokinesis.

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The Cell Cycle
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The Cell Cycle

• Interphase
• This is the period between cell divisions.
• This period can be quite long, whereas cell
  division occurs quickly.
• Interphase is divided into the following three
  phasesG1, S, and G2.

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The Cell Cycle

• Interphase
• G1( or gap 1) phase cellular growth
  development take place.
• S (or DNA synthesis) phase DNA replication
  takes place several proteins, including those
  associated with the chromosomes, are produced.

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The Cell Cycle

• Interphase
• G2 (or gap 2) phase usually the shortest phase
  of the 3, it involves the synthesis of
  organelles materials needed for cell division.
• Although the cell seems to be quiet during
  interphase, it is actually a period of intense
  activity with ATP production use, DNA
  replication, and protein synthesis.

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The Cell Cycle Interphase
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The Cell Cycle

• Mitosis (or the M phase)
• This is the process by which the cells nucleus
  divides into two nuclei.
• Depending on the cell type, it may last from a
• few minutes to several days.
• Mitosis is divided into four phases prophase,
  metaphase, anaphase, telophase.

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The Cell Cycle

• Mitosis (or the M phase)
• Prophase (1st phase) Longest phase.
• Chromosomes appear due to chromatin condensing
  and coiling.
• Centrioles move to opposite sides of the
  nucleus.
• Spindles develop from the centrioles attach to
  the chromosomes at the centromere.
• Nuclear envelopes breaks down and the nucleolus
  disappears.

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The Cell Cycle
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The Cell Cycle
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The Cell Cycle Mitosis (Prophase)
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The Cell Cycle

• Mitosis (or the M phase)
• Metaphase (2nd phase) Shortest phase.
• Chromosomes line up across the center or
  equator of the cell.
• Microtubules connect the centromere of each
  chromosome to the poles of the spindle.
• Microtubules are called asters which is the Greek
  word for star.

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The Cell Cycle Mitosis ( Metaphase)
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The Cell Cycle

• Mitosis (or the M phase)
• Anaphase (3rd phase)
• It begins when the centromeres split.
• This causes the sister chromatids to separate
  move near the poles of the spindle.
• It ends when the chromosomes stop moving.

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The Cell Cycle Mitosis ( Anaphase)
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The Cell Cycle

• Mitosis (or the M phase)
• Telophase (final phase)
• Chromosomes begin to uncoil into a tangle of
  chromatin.
• Nuclear envelope reforms around chromatin.
• The spindle begins to break apart the
  nucleolus becomes visible.

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The Cell Cycle Mitosis (Telophase)
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The Cell Cycle

• Cytokinesis
• This is the division of the cytoplasm into two
  individual cells.
• It quickly follows mitosis.
• Animal cells
• The cell membrane moves inward until the
  cytoplasm is pinched into two parts.
• Each new half has its own nucleus and
  cytoplasmic organelles.

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The Cell Cycle

• Cytokinesis
• Plant cells
• A cell plate forms midway between the divided
  nuclei.
• Then a cell wall appears in the cell plate.

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The Cell Cycle Cytokinesis (plant cell)