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Cells: A Review 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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Cells: A Review

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Cells: A Review


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!)


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'


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


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.


Unicellular or multicellular?

Some complete organisms are made of only one cell.

Some are made of only a few cells.


Others are made of many cells.


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


Nucleus - directs the activity of a cell; it contains chromosomes made of DNA

Nuclear Membrane - separates the nucleus from the rest of the cell


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


Ribosomes - make protein for the cell


Mitochondria - break down food and release energy to the cell


Vacuoles - are storage areas for the cell

exocytosis and endocytosis


Lysosomes

  • The cell’s recyclers.

  • The garbage men of the cell.


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


We will look at these cells!

Onion cells

Cheek cells

(stained)

Elodea cells (plant)


Microscopes

micro = small

+

scope = to look

Light Microscopes

  • 1. Simple

    • a. one lens

    • b. first invented in 1500’s

  • Compound

    • two lenses

    • We use this one in class.


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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