Cells: A Review

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Cells A Review
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A Little History. . .

• English scientist, Robert Hooke (1665)

• looked at cork through a compound microscope
• saw tiny, room-like structures
• called these structures 'cells'
• saw only outer walls - cork cells are not alive
• (But they used to be!)

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Dutch fabric merchant and amateur scientist,
Anton van Leeuwenhoek (1680)

• looked at blood, rainwater, scrapings from teeth
  through a simple microscope
• observed living cells
• called these 'animalcules'

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German scientists

• Matthias Schleiden (1838)
• Said that plants are made of cells

Schleiden

• Theodor Schwann (1839)
• Said that animals are
• made of cells

Schwann

• Rudolph Virchow (1854)
• Said that new cells form
• when old cells divide.

Virchow
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Cell Theory
The work of Schleiden, Schwann and Virchow led to
the development of the cell theory.

• All living things are made of one or more cells.
• Cells are the basic unit (building block) of all
  living things.
• All cells come from cells that already exist.

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Unicellular or multicellular?
Some complete organisms are made of only one cell.
Some are made of only a few cells.
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• Others are made of many cells.

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Parts of a Cell All cells have some very basic
parts.
Cell Membrane - forms the outer boundary of the
cell and allows only certain materials to move
into or out of the cell
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• Nucleus - directs the activity of a cell it
  contains chromosomes made of DNA

Nuclear Membrane - separates the nucleus from the
rest of the cell
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• Endoplasmic Reticulum - moves materials around in
  the cell
• (called ER for short)

Golgi Bodies - are used for packaging and
secreting hunks of ER pinch off to form Golgi
bodies
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• Ribosomes - make protein for the cell

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• Mitochondria - break down food and release energy
  to the cell

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• Vacuoles - are storage areas for the cell

exocytosis and endocytosis
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Lysosomes

• The cells recyclers.
• The garbage men of the cell.

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• Cytoplasm - a gel-like material inside the cell
  that is made of water nutrients

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We will look at these cells!
Onion cells
Cheek cells (stained)
Elodea cells (plant)
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Microscopes

• scope to look

micro small


Light Microscopes

• 1. Simple
• a. one lens
• b. first invented in 1500s
• Compound
• two lenses
• We use this one in class.

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Electron Microscopes

• TEM
• Transmission electron microscopes
• invented in 1931
• two dimensional image

2. SEM

• Scanning electron microscopes
• invented in 1981
• three dimensional image
• May be referred to as tunneling

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