GCSE Biology (AQA)

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Microscopes

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Cell Biology Cell Structure

Microscopes

4:11 Microscopy
Spec 4.1.1.5
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  • Light microscopes use magnifying lenses to focus and reflect light waves to magnify objects.
  • The first light microscopes were likely invented in the 1590s in the Netherlands by eyeglass makers.
  • Modern light microscopes differ significantly from early examples.
  • For exams, knowledge of light microscope types is required, but not their historical details.
  • A typical light microscope includes an objective lens (with options like 5x, 10x, 25x magnification), a stage for the specimen, a light source, an eyepiece, and focusing dials (coarse and fine).
  • Electron microscopes, invented in 1931 by German scientists, use electron beams to create images on computer screens.
  • There are two types of electron microscopes: Transmission Electron Microscopes (TEM) for examining thin cell/tissue sections (invented in 1931) and Scanning Electron Microscopes (SEM) for examining surface structures (invented in 1937).
  • Electron microscopes offer greater magnification and resolution than light microscopes, allowing for the visualization of subcellular structures in finer detail.
  • Light microscopes have a maximum resolution of about 200 nanometers, limiting their ability to distinguish points closer than 200 nanometers apart.
  • Electron microscopes can achieve resolutions as fine as 0.1 nanometer.
  • Electron micrographs are typically black and white but can be colorized using computer software.
  • Understanding the development of microscopy techniques and the impact of electron microscopy on the study of subcellular structures is crucial for exams.

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