Download Cell_Theory_and_Microscopes_2011

CELLS
Smallest unit
of life that
can carry out
all the
functions of
an organism.
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:
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.
These discoveries, confirmed by other
biologists, are summarized in the CELL
THEORY
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)
Examples of Cells
Amoeba Proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Part of the Microscope
Parts of the Microscope
A. Occular (eye
piece)
B. Body Tube
C. Revolving
Nosepiece
D. Objective
Lenses
E. Stage
F. Diaphragm
(controls
amount of
light)
Parts of the Microscope
G. Light source
H. Base
I. Fine Adjustment knob
J. Coarse Adjustment Knob
K. Stage Clips (holds slides)
L. Arm
Carrying a Microscope
Magnification increases the apparent
size of a specimen when you view it
through the microscope.
Calculating Magnification
Magnification of
objective lens
X occular lens magnification
Since microscopes magnify cells we have
a new unit of measurement.
These new units are called microns.
1mm
1
1000
=
1000 µm
=
1 µm
We can use microscopes to estimate the
size of cells we are looking at.
Example
a)if the Field
fieldof view
of view = 1mm
Onion cell
1mm (1000 µm)
then0.5onion cells are
______________
mm
500 microns
or ______________(µm) in length
b)if the field of view = 0.5mm or 500µm
then these cheek cells would be
500
5
100 µm in length
mm or ______________
0.5 mm (500 µm)
Human cheek
cell