AQA A Level Biology复习笔记2.2.7 Scientific Research into Cell Organelles
Appreciating the Process of Distinguishing Organelles
- When looking at a?prepared sample?(e.g. a cell or a group of cells) under a microscope, you can sometimes see things that aren’t actually part of the specimen
- These are known as?artefacts
- Artefacts can be a variety of things, such as:
- dust
- air bubbles
- fingerprints
- These artefacts often occur during the?preparation?of a sample
- During preparation, a sample is often?squashed?or?stained, which can generate artefacts
- The occurrence of artefacts can be?decreased?by?more careful preparation?of samples
- Artefacts are?common?in?electron micrographs?(especially in samples prepared for viewing using a transmission electron microscope) due to the?lengthy treatment?required to prepare samples
- This was particularly problematic for?early research?by scientists using the first electron microscopes
- To?distinguish?between artefacts and organelles, they had to repeatedly prepare a specimen in?different ways, using different techniques
- If they saw a particular object in a specimen prepared using?one?preparation technique, but?not another, the object was more likely to be an?artefact?than an?organelle
- This was a problem for the scientific community that?persisted?for a considerable period of time until preparation techniques and knowledge of organelles?improved
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