From Lab manual

• Bright field microscopy


  Can magnify 1,000 - 1,500 x<|>Used to visualize bacteria and fungi<|>Specimen appears dark against surrounding brighter view<|>Very low contrast, specimen needs to be stained to be properly viewed
• Dark field microscopy


  Utilizes REFLECTED light instead of transmitted light<|>Specimen appears bright against a DARK BACKGROUND<|>Ideal for studying specimens that are unstained / transparent<|>Used to view SPIROCHETES
• Phase-contrast microscopy


  Contrast enhancing optical technique to produce high contrast images of transparent specimens, including THIN TISSUE SLICES and SUBCELLULAR PARTICLES (such as nuclei and organelles)
• Differential interference contrast (DIC) microscopy


  Similar to phase contrast, except it utilizes 2 beams of light instead of 1, therefore has HIGHER RESOLUTION<|>Useful in examining LIVING SPECIMENS when normal biological processes might be inhibited in standard staining procedures
• Fluorescence microscope


  Makes use of UV light and fluorescent dyes called FLUOROCHROMES<|>Visualize structural components of small specimens such as cells and to detect VIABILITY OF CELL POPULATIONS<|>Visualize genetic material of the cell (DNA and RNA)
• Confocal microscopy


  Uses a spatial pinhole to block out-of-focus light in image formation<|>Scanned with a laser into planes and regions, produces 3-D image<|>Useful in the study of cell physiology
• Scanning probe microscopy


  Used to study the molecular and atomic shapes of organisms on a nanoscale<|>Physical probe is used to scan back and forth over the surface of the sample<|>A computer gathers the data and generates an image<|>Determine variations in temperature inside the cell as well as its chemical properties
• Electron microscope


  Utilizes BEAM OF ELECTRONS to create an image of the specimen<|>Magnets are used to focus the beam<|>Modern microscopes are capable of magnifying objects 2 MILLION TIMES the original size<|>Visualize VIRUSES and SUBCELLULAR STRUCTURES OF THE CELL
• Types of electron microscopes

  • Transmission Electron Microscope (TEM)
  • Scanning Electron Microscope (SEM)
• Transmission Electron Microscope (TEM)


  Original form of the electron microscope<|>Produces 2-D, black & white images, magnifies 200,000 x
• Scanning Electron Microscope (SEM)

  Magnify bulk samples with greater depth of view so that image represents a 3-D structure of the sample, but the image is still only black and white<|>It can magnify the object up to 10,000 times
• All cocci are gram positive except Neisseria, Veilonella and Branhamella
• All bacilli are gram negative except Corynebacterium, Clostridium, Bacillus, Bacillus, and Mycobacterium