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Chapter 3Section 1 Microscopes
Units of Measure Metric system of measurement
International System of Measurement SI Base Unit is the Meter (m)
Kilometer = 1,000 m (2/3 of a mile) Centimeter = .01 m (1/2 diameter of
penny) Millimeter = .001 m (width of pencil tip) Micrometer = .000001m (bacteria cell) Nanometer = .000000001 m (water mol.)
Light Microscopes Light passes
through one or more lenses to produce an enlarged image of a specimen
Electron Microscopes Forms an image of
a specimen using a beam of electrons rather than light
3 Types Transmission
electron microscopes (TEM)
Scanning electron microscope (SEM)
Scanning tunneling microscope
Micrographs The image
produced by the microscope Type of microscope Magnification Name of object
Light Microscope 320 magnification Amoeba
Magnification & Resolution Magnification
Makes the image appear larger than its actual size
Resolution A measure of the clarity of an image
High magnification & good resolution are needed to view details of extremely small objects clearly.
Limitations of Microscopes Light microscopes: lower
magnification power but can view LIVING cells
Electron microscopes: higher magnification but cannot view living cells
Light Microscope Ocular lens -
closest to the eye Objective lens -
closest to the specimen
Both magnify 40x objective &
10x ocular = 400x magnification
Electron Microscopes Can magnify 200,000x Both electron beam and specimen
must be placed in a vacuum chamber Living cells cannot be viewed 3 Types
Scanning Electron Microscopes (SEM) Transmission Electron Microscopes (TEM) Scanning Tunneling microscopes
Scanning Electron Microscope
Specimen is coated with a thin layer of metal
3-D image of cell surfaces
Black & white image that can be artificially colored
Thin metal coating
SEM of Human Blood
Foot of a House Fly SEM x300
Transmission Electron Microscope
Cross section of specimen
Non living Stain with metal ions Electrons pass
through specimen & form image
Image is in black & white (Can be enhanced with color)
Corona Virus (TEM)
Cytoplasm of Liver Cell (TEM)
Bacteriophages (TEM)
Golgi Apparatus (TEM)
Scanning Tunneling Microscope
3D image of the specimen’s surface
Can be used on living organisms
Scanning Tunneling Image