Transcript Microscopy - Petal School District

Microscopy
Light and Electron Microscopy
The First Light Microscopes
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Around 1590 Zaccharias and Hans Janssen
experimented with lenses in a tube, leading
to the forerunner of the microscope and the
telescope
In the late 1600’s, Anton van Leeuwenhoek
was the first to see bacteria, yeast, and many
other microbes using a microscope
How Light Microscopes Work
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First, the objective lens gathers light from the
specimen and magnifies the image
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The ocular lens in the eyepiece magnifies and
transmits the image to your eye
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Most microscopes have several objective lenses that
can be rotated into position to provide different
levels of magnification (4X, 10X, 40X)
The magnification of the ocular lens is 10X
To find the total magnification of the microscope
you are using, multiply the magnification of the
objective lens by the magnification of the ocular
lens.
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For example: 40X (objective lense) x 10X (ocular
lense) = 400X magnification
The Parts of a Light Microscope
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Light source: Could be a mirror, but
most likely it is a bulb built into the
base
Diaphragm: Adjusts the amount of
light striking an object
Objective lens: Gathers light and
magnifies image
Ocular lens (eyepiece): Magnifies
objects and focuses light to your eye
Stage: Holds slide
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Can be moved using the coarse or fine
adjustment knobs to bring the object
into focus
Stage clips: Hold slide in place
Base and arm: Structural support for
the microscope
Can you name the parts?
Start on the left side and work from the top down. Then go to the right
side and work from the top down.
Ocular lens (eyepiece)
Arm
Objective Lenses
Stage clip
Stage
Course adjustment
Diaphragm
Fine adjustment
Light Source
Base
Nice Job !
Images Produced by Light
Microscopes
Amoeba
Streptococcus bacteria
Anthrax bacteria
Human cheek cells
Plant cells
Yeast cells
Beyond Light Microscopes
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Light microscopes are limited by
their resolution.
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Light microscopes cannot produce
clear images of objects smaller
than 0.2 micrometers
The electron microscope was
invented in the 1930’s by Max
Knott and Ernst Ruska
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Electron microscopes use beams
of electrons, rather than light, to
produce images
Electron microscopes can view
objects as small as the diameter of
an atom
Types of Electron Microscopes
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Transmission electron microscopes (TEMs) pass
a beam of electron through a thin specimen
Scanning electron microscopes (SEMs) scan a
beam of electrons over the surface of a
specimen
Specimens from electron microscopy must be
preserved and dehydrated, so living cells cannot
be viewed
Images Produced by Electron
Microscopes
Cyanobacteria
(TEM)
House ant
Lactobacillus
(SEM)
Avian influenza
virus
Campylobacter
(SEM)
Human eyelash
Deinococcus
(SEM)
Yeast
Using Microscopes to Visualize the
Three Shapes of Bacteria
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Cocci (round)
Bacilli (rod)
Spirilla (spiral)
Three shapes of bacteria
taken with an SEM
Light microscope:
Cocci
Bacilli
Spirilla
References
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http://education.denniskunkel.com/catalog/pro
duct_info.php?products_id=1123
http://micro.magnet.fsu.edu/
http://inventors.about.com/library/inventors/b
lroberthooke.htm