Exploring life
CHAPTER 1 LESSON 3
THE DEVELOPMENT OF THE MICROSCOPE
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Allowed people to see details of an object
that they could not see before
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Robert Hooke- in the 1600’s used a
microscope to look at cork
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He was the first scientist to name cells
because they resemble “prison cells”
He was looking at the remains of the cell wall
in the cork
THE FIRST MICROSCOPES
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Anton van Leeuwenhoek- Dutch merchant
Late 1600’s
Made improvements to the existing
microscopes
Microscopes could not magnify up to 270 time
the original size
CHARACTERISTICS OF MICROSCOPES
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Magnification of the microscope
 Magnification
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makes the object look bigger
Resolution of a microscope
 How
clearly you can see the object has to do with
the resolution of the microscope
TYPES OF MICROSCOPES
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Two major types based on the source of
illumination
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Light
Electron
Electron
Light
LIGHT MICROSCOPES
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Uses a light source or mirrors to enlarge an object
Some light microscopes have a single lens
The microscope we use is a compound microscope
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Two lenses
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1. In the ocular
2. In the objective
To find the magnification you MULTIPLY the ocular value by
the objective
Example: Ocular 4 X
Objective 10 X
So total magnification is 4 x 10 or 40 X
RESOLUTION OF LIGHT MICROSCOPES
0.2 micrometers or two millionths of a
meter
 Dyes maybe used to help visualize parts
of the cell
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ELECTRON MICROSCOPES
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Use a magnetic field to focus a beam of
electrons through an object
Can magnify up to 100,000 times or more
(light can only magnify up to 1500 times)
The resolution is 0.2 nanometers or two
billionths of a meter
TEM
SEM
TWO TYPES OF ELECTRON
MICROSCOPES
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Transmission
electron
microscopes (TEMs)
Study extremely
small structures in
cells
Specimen needs to
be in plastic and
then thinly sliced
Only dead
specimens can be
used
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Scanning electron
microscopes (SEMs)
Study the objects
surface
Electrons bounce off
the image and
produce a 3 D image
on the computer
Can be a living
specimen
REAL WORLD USES OF MICROSCOPES
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Health care
 Laboratory
to study specimens like
blood
 Surgery like cataracts or brain surgery
 Determine if tissue sample has cancer
or not
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Forensics
 Crime
scenes- to determine body
fluids and insect data
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Archeologists
 Study
fossils and the material
surrounding the fossil