Transcript Chapter 2: The Microscope

Tooth with plaque
Magnification: 10X
Toothbrush and Tooth
Magnification: 75X
Human Finger tip
Magnification: 12X
Human Finger tip
Magnification: 600X
Human Skin with Bacteria
Magnification: 8,000X
Mosquito
Magnification: 50X
Human Cells
Magnification:
10,000X
Embryonic Hand
Magnification 7X
5 weeks
Embryonic Hand
Magnification 10X
11 weeks
Human Embryo
Magnification 10X
16 weeks
Stomach Pit with Red Blood Cell and Acid
Magnification: 3,000X
Human Brain
Magnification: 5X
6 week Human Embryo
Magnification: 10X
The Microscope
• Microscope—tool used
to study things too small
to be seen by the
unaided eye.
• History:
– Invented by the Jansen
brothers in 1590.
– Improved by Anton Van
Leeuwenhoek in the
1600’s.
• His first scope had a power
of 270X.
• He made over 400 different
microscopes.
• Known as the “Father of
Microbiology.”
Anton Van Leeuwenhoek
Types of Microscopes
• Compound Light Microscope —
uses lenses to magnify and light to
illuminate. The most powerful can
magnify 2000X.
– Eyepiece —lens closest to the eye.
– Objective lens —lens closest to the
object.
– Total magnification —the power of
the eyepiece times the power of the
objective.
– Example: 10X x 43X =
430X
Types of Microscopes
• Stereoscope —used
to view larger objects.
The light source is
above the object, not
below.
Types of Microscopes
• Electron Microscope —uses magnets to focus a
beam of electrons.
– Electrons are negatively charged particles.
– Total magnification can be up to 1,000,000X.
– Disadvantages—sometimes can not study living
organisms; expensive; too powerful
– Types:
• Transmission Electron Microscope (TEM)—used to study
internal parts of a specimen.
• Scanning Electron Microscope (SEM)—used to see the
surface of whole objects.
• Scanning Tunneling Microscope—the most powerful.
Invented in 1981. Has a magnification of 100 million times
and a resolution of 1/100th the diameter of an atom.
Transmission Electron
Microscope
• The TEM passes electrons through the object
being studied. It can magnify as much as
200,000x but can not be used to observe living
tissue.
• The TEM gives very detailed pictures of
the internal structure of materials, either
biological or non-biological.
Example: Golgi body of an a
animal cell.
Scanning Electron Microscope
• The SEM has a
magnification range of
15x to 200,000x and a
resolution of 5
nanometers.
• It produces a detailed,
three dimensional black
and white image
35x
200x
1000x
35000x
• Specimens to be viewed by the SEM must
be carefully dried to prevent shriveling and
must be made to conduct electricity by
coating them with a thin layer of gold in a
machine called a sputter coater.
Dried specimen
Sputter coater
• Finally, the specimen is placed in the
microscope’s vacuum column through an
air-tight door. Air is pumped out and an
electron gun emits a beam of high-energy
electrons which is focused by a series of
magnets.
• The Scanning
Tunneling Microscope
invented by John
Wendelken and Joe
Carpinelli. The
microscope is
nicknamed JEOL.
Microscope Diagram
Microscope Flipchart
Activity
Revolving Nosepiece
Objective lenses
Stage
Diaphragm
Light
Base
Eyepiece
Eyepiece Tube
Body
Arm
Stage Clips
Coarse Adjustment
Fine Adjustment