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Microscopy

Microscopy. Micro = ‘very small’ Scope = ‘to see’ Early biologists could only examine what they could see with the naked eye. Middle ages : Used a single lens magnifying glass (10-30X power) 1590: Two Dutch eyeglass maker – Hans and Zacharias Janssen Made the first compound microscope

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Microscopy

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  1. Microscopy

  2. Micro = ‘very small’ • Scope = ‘to see’ • Early biologists could only examine what they could see with the naked eye

  3. Middle ages: Used a single lens magnifying glass (10-30X power) • 1590: Two Dutch eyeglass maker – Hans and Zacharias Janssen • Made the first compound microscope • Two lenses on opposite ends of a tube

  4. Late 1600s: Anton van Leeuwenhoek ground glass to make many microscopes • Used a single lens, but was able to get a magnification over 200X • He was the first to see living cells • This was the start of microbiology

  5. Types of Microscopes • Light Microscope • Uses light (from mirror or light source) • Most have several objectives • Different powers • Can magnify up to 2000X • Unit of measurement: micron • Aka: A micrometer (1/1000 mm) • Light microscopes are limited by their resolving power (resolution) which is the ability to see objects close together clearly and separate

  6. TEM: Transmission Electron Microscope • Invented in the 1930s • Uses a stream of electrons instead of light and magnets to focus the beam • The e- beam passes through the subject • 200,000X magnification • Can enlarge to ~ 1 million • Very good resolution, but cannot view living specimens

  7. SEM: Scanning Electron Microscope • Magnification up to 100,000X • Still can’t view living things (vacuum) • See the surface of the object (3D)

  8. Other Biological Tools • Ultra centrifuge • Spins out different sized particles and heavier particles fall to the bottom

  9. Chromatography • Paper: A spot of a mixture is placed on paper and the edge of the paper touches a liquid • As the liquid is drawn up, the different substances in the mixture travel different distances • Column: uses a glass column, same principle

  10. Electrophoresis • A mixture is placed on a gel-like tray and electric current moves the proteins in the mixture different distances

  11. X-ray Diffraction • Used to see the structure of crystals or large molecules • The x-rays are bent or scattered as they pass through a crystal, creating a pattern

  12. Parts of a Microscope • 1. Ocular Lens (eyepiece) • Lens system at top of tube • 2. Arm • Supports lenses, used for carrying • 3. Stage • Platform to hold slide • 4. Coarse Adjustment Knob • Crudely adjusts focus

  13. 5. Fine Adjustment Knob • Critically adjusts focus • 6. Base • Solid support for the microscope • 7. Body Tube • Carries light from the objective lens to the eyepiece • 8. Revolving Nosepiece • Supports the objective lenses

  14. 9. Objectives • At bottom of body tube • Magnifies object • 10. Stage Clips • Hold slide in place • 11. Diaphragm • Regulates amount of light • 12. Light Source • Directs light into the lens

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