Introduction%20to%20Cells

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Introduction to Cells

• Biology A/Cells

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The Discovery

• Cells were first discovered in 1665 when Robert
  Hooke observed a slice of cork under a
  microscope.
• Hooke thought the small divisions looked like the
  monastery cells that monks lived in.

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The Discovery

• Anton van Leeuwenhoek was the first to observe
  micro-organisms in 1674, when he observed a drop
  of water under a microscope.

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The Discovery Continues

• The combined work of a number of other scientists
  finally led to the development of the cell theory.

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The Cell Theory

• All living things are made of cells.
• Cells are the basic units of structure and
  function in living things.
• New cells are only produced by other cells.

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Micro-organisms

• We will discuss 3 main types of micro-organisms
• 1. Viruses
• 2. Bacteria
• 3. Protists

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Bacteria

• Bacteria are microscopic, single-celled
  organisms.
• Bacteria are prokaryotes which means that their
  DNA is not contained inside the protective
  coating of a nucleus.

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• Cross off Protists section ?

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Viruses

• Viruses are the simplest and smallest
  micro-organisms.
• They contain a small amount of DNA (genetic
  material) and a protective coat called a capsid.
• Viruses reproduce by attaching to another cell
  and overriding normal cell functioning so that
  the cell produces new viruses.

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2 Categories of Cells

• Prokaryotic Cells Eukaryotic Cells

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Prokaryotic Cells

• Do not contain a nucleus
• Are smaller and simpler than eukaryotic cells
• Example Bacteria

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Eukaryotic Cells

• Have a nucleus
• Are larger and more complex than prokaryotic
  cells
• Contain specialized structures called organelles
• Examples Plant cells
• Animal cells

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Protists

• Protists are generally larger than viruses and
  bacteria, but they are still microscopic.
• Protists are eukaryotes, which means their DNA is
  contained in a protective nucleus.