Advances in microscopy improve resolution, contrast, molecular specificity, and preservation, allowing cellular surfaces, internal ultrastructure, and selected molecules to be distinguished.
Coverage 2017–2025 · Updated 15 Jul 2026
Microscopy advances improve resolution, preserve different structures or attach molecular identity; the best method depends on the evidence required.
| Method | Main advantage | Typical evidence |
|---|---|---|
| TEM | High-resolution electrons pass through a thin section | Internal ultrastructure |
| SEM | Electrons scan a surface | Three-dimensional surface detail |
| Freeze fracture | Frozen membranes split along the bilayer | Membrane faces and embedded proteins |
| Cryogenic EM | Rapid freezing preserves near-native structure | High-resolution molecular or cellular structure without conventional staining |
| Fluorescent stain | Fluorophore marks a selected structure | Location of labelled material in a light microscope |
| Immunofluorescence | Labelled antibodies bind a target antigen | Location of a specific protein |
A fluorescent antibody can locate one membrane protein, whereas freeze fracture can reveal particles embedded in the membrane face without identifying their molecular name.
Electron micrographs and fluorescence images may use false colour. Colour is not automatically part of the specimen.
This objective is assessed through multiple choice, commonly using State / Identify.
State / Identify
Build the answer around this relationship: Resolution is the ability to distinguish two nearby points as separate.
Using magnification and resolution as if they describe the same property.
Representative question
What is a feature of immunofluorescence in light microscopy?
Can only be used on dead cells
Enables higher resolution
Attaches a fluorescent stain to an antibody
Attaches a fluorescent stain to an antigen
The SL core is a practical chain. First, understand cells as structural and functional units. Then use microscopes correctly: prepare, stain, calibrate, measure, and choose a method based on resolution and the detail needed. Finally, identify cell types from visible evidence and draw only what the micrograph shows. This is how the topic turns from definitions into exam performance.
