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Chapter 3

Chapter 3. Section 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)

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Chapter 3

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  1. Chapter 3 Section 1 Microscopes

  2. 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.)

  3. Light Microscopes • Light passes through one or more lenses to produce an enlarged image of a specimen

  4. 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

  5. Micrographs • The image produced by the microscope • Type of microscope • Magnification • Name of object • Light Microscope • 320 magnification • Amoeba

  6. 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.

  7. Limitations of Microscopes • Light microscopes: lower magnification power but can view LIVING cells • Electron microscopes: higher magnification but cannot view living cells

  8. Light Microscope • Ocular lens - closest to the eye • Objective lens - closest to the specimen • Both magnify • 40x objective & 10x ocular = 400x magnification

  9. 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

  10. 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

  11. Thin metal coating

  12. SEM of Human Blood

  13. Foot of a House Fly SEM x300

  14. 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)

  15. Corona Virus (TEM)

  16. Cytoplasm of Liver Cell (TEM)

  17. Bacteriophages (TEM)

  18. Golgi Apparatus (TEM)

  19. Scanning Tunneling Microscope • 3D image of the specimen’s surface • Can be used on living organisms

  20. Scanning Tunneling Image

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