Summary
TEM and SEM use electron beams to achieve resolution thousands of times better than light microscopes.
In depth
TEM transmits electrons through ultrathin sections (below 100 nm); SEM scans a surface coated with gold for 3D images. Resolution about 0.1 nm for TEM. Artefacts can arise from fixation.
Samples are fixed, dehydrated, embedded and sliced for TEM. SEM needs conductive coating. Images are greyscale; colours are added artificially.
Key idea: electron microscopes reveal ultrastructure but cannot view living cells.
Electron microscopes use beams of electrons, which have wavelengths about 100,000 times shorter than visible light, giving much higher resolution. Transmission electron microscopes (TEM) pass electrons through ultra-thin sections, showing internal structure at about 0.1 nm resolution; scanning electron microscopes (SEM) scan a beam across the surface, giving 3D-like images of surfaces at about 1 to 10 nm.
Samples must be fixed, dehydrated and put in a vacuum, so living cells cannot be observed, and images are in greyscale (colour is added artificially). Sample preparation can cause artefacts. Cryo-EM freezes samples in ice to preserve structure.
Example: TEM showed membranes, ribosomes and mitochondria in detail.
Remember: TEM for inside, SEM for surface.
Frequently asked questions
What is Electron Microscopy?
TEM and SEM use electron beams to achieve resolution thousands of times better than light microscopes.
Which area of biology covers Electron Microscopy, and how advanced is it?
Electron Microscopy is one of the 51 topics in Lab Methods & Biostatistics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Magnification and Resolution, Confocal Microscopy, Light Microscope.
Can you give an example of Electron Microscopy?
TEM first revealed the internal structure of mitochondria.
What should I learn before Electron Microscopy?
Work through the Beginner topics in Lab Methods & Biostatistics first, such as Scientific Method, Hypothesis, Variables, then return to Electron Microscopy. Intermediate topics assume the Beginner vocabulary.
What topics are related to Electron Microscopy?
The closest topics to Electron Microscopy are Magnification and Resolution, Confocal Microscopy, Light Microscope, Super-Resolution Microscopy. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Electron Microscopy?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Electron Microscopy. To practise the whole of Lab Methods & Biostatistics, use the Lab Methods & Biostatistics quiz.
How is Electron Microscopy different from Magnification and Resolution?
Electron Microscopy: TEM and SEM use electron beams to achieve resolution thousands of times better than light microscopes. Magnification and Resolution: Magnification enlarges an image, while resolution is the ability to distinguish two close points. Read both side by side and note what each one explains.
How should I study Electron Microscopy step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Magnification and Resolution and explain the difference aloud. Finally, take the Lab Methods & Biostatistics quiz and come back to this page for any question you miss.