Electron Microscopy and Gram Staining

Electron Microscopy

• Core Components and Operation:

  • Utilizes electromagnetic lenses, an electron beam, and a fluorescent screen to visualize micro-structures.
  • Replaces traditional dyes with heavy metals to generate contrast in samples.

• Magnification Capability:

  • Can amplify and magnify objects up to $100,000\times$

Hans Christian Joachim Gram ($1853\text{--}1938$)

• Historical Background and Discovery:

  • Worked as a physician in a morgue in order to better understand pneumonia.
  • Revealed that two different types of bacteria were responsible for causing pneumonia.
  • Discovered that these two distinct bacterial groups retained dye in different ways during staining procedures.

• The Gram Stain Method:

  • The procedure is known today as the Gram stain.
  • Differentiates and identifies two fundamental groups of bacteria:
  • Gram-positive
  • Gram-negative

• Diagnostic Significance:

  • Serves as the overall key test in the initial identification of a bacterium.