Review:
­ Redi
­ Needham
­ Spallanzani
­ Pasteur
­ Leeuwenhoek
­ why their discoveries disproved spontaneous generationi
Sep 13­11:35 AM
The Microscope (pages 12 ­ 14)
­ the microscope consists of a lens or combination of lenses that produce enlarged images of small objects
­ earliest microscopes were a single curved lens mounted on a metal plate (similar to a magnifying glass)
Sep 13­11:44 AM
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­ later the compound light microscope was developed
­ it had two lenses (ocular and objective) and total magnification was determined by multiplying the power of the ocular by the objective
­ newer microscopes had improved resolution which refers to its ability to distinguish between objects that are close together
Sep 13­11:48 AM
Types of Microscopes:
1. Compound microscope
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­
uses light and a combination of lenses to enlarge small objects
maximum magnification of about 2000X
Sep 13­11:51 AM
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2. Transmission Electron Microscope: (TEM)
­ directs a beam of electrons through an object
­ object must be thin and treated with chemicals for an accurate image to be obtained
­ maximum magnification of to 50,000,000X
Sep 14­7:44 AM
3. Scanning Electron Microscope: (SEM)
­ uses electrons to take pictures of the specimen and displays it on a television screen
­ uses the whole organism to produce almost 3­d images
­ maximum magnification is about 500,000X
Sep 14­7:49 AM
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What is this?________________
Which microscope was used?
___________________________
See pages 20 ­ 21 for more information
Sep 14­7:55 AM
Parts of a Microscope
a.Ocular Lens: magnifying lens you look through
b. Ocular Tube: holds the ocular lens
c. Coarse Adjustment Knob: move the stage up and down to bring an object into focus
d. Fine Adjusting Knob: brings an object into sharper focus (use with medium/high)
e. Revolving Nosepiece: holds two or more objective lenses which you can rotate or change
f. Arm: connects the body tube with the base (use it for carrying)
g.Objective Lens: magnify the object on a slide
h. Stage Clips:
hold the slide in place
Sep 14­7:56 AM
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i. Stage: platform that supports the slide
j.Disk diaphragm: controls the amount of light that reaches the object
k. Inclination Joint: pivots the microscope
l. Light Source (mirror): directs light through the diaphragm to help with observation
m. Base:
supports the microscope
Sep 14­3:06 PM
Readings:
Pages 12 ­ 21
Activities:
Complete handout on microscope
Sep 14­3:09 PM
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