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History of the Cell:• 1665 – Robert Hooke discovered and described the fundamental unit of all living things (cells) by using thin slices of cork.• He gave the tiny chambers the name “cell” because it reminded him of a monastery's tiny room which were known as cells.
History of the Cell:
• 1674 – Anton Van Leeuwenhoek (“Father of Microbiology”) was the first man to witness a live cell under a microscope.
• He made many different types of single lens microscopes that could magnify up to 300 X.
• When observing pond water, he discovered tiny organisms he called "animalcules.”
History of the Cell:
• 1838: Matthias Schleiden (Botanist) concluded that all plants are made out of cells.
History of the Cell:• 1839: Theodor Schwann (Zoologist) concluded
that ALL organisms including animals are made up of cells.
History of the Cell:
• 1855: Rudolph Virchow (Doctor) – proposed that all cells arise from existing cells.– Until 1855: Schleiden and Schwann believed that cells
might “crystallize out” from fluids.
What is the Cell Theory?A fundamental concept in biology that
states:
1. Cells are the basic units of life (Hooke)2. All organisms are made of cells
(Schleiden &Schwann)3. All cells come from existing (other) cells
(Virchow)
Parts of the MicroscopeA. Occular (eye
piece)B. Body TubeC.Revolving
NosepieceD.Objective
LensesE. StageF. Diaphragm
(controls amount of light)
G. Light sourceH. BaseI. Fine Adjustment knobJ. Coarse Adjustment KnobK. Stage Clips (holds slides)L. Arm
Parts of the Microscope
Magnification increases the apparent size of a specimen when you view it through the microscope.
Calculating Magnification
Magnification of X occular lens magnification
objective lens
Since microscopes magnify cells we have a new unit of measurement.
These new units are called microns.
1mm = 1000 µm 1 = 1 µm1000
We can use microscopes to estimate the size of cells we are looking at.
a)if the field of view = 1mm
then onion cells are
______________ mm
or ______________(µm) in length
1mm (1000 µm)
Field of view
Onion cell
0.5
500 microns
Example