Revealing viruses
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Bernard Nebel.
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The infectious disease-causing particles (viruses) were seen for the first time under the newly developed electron microscope in the 1930s. Type into your browser: electron micrographs of viruses images
Note different viruses have specific shapes and structures allowing them to be classified much like other organisms. Then, chemical analysis showed viruses to consist of genetic material, DNA or RNA, surrounded by a “shell” of protein, nothing more. Type into your browser:
basic structure of a virus diagram images/
Ask students: How does this explain why they can’t be cultured? Lacking any cellular apparatus for metabolism, much less cell division, viruses can’t grow by themselves. They highjack the host’s metabolic system to manufacture copies of themselves as shown in this video:
Seeing this life cycle, it is easy to see how virus infections can become deadly. Fortunately, organisms have evolved a defense system, an immune system, that fights infection. A brief, highly simplified overview of this system may be seen here:
The details of he immune system, as they have been gradually worked out by scientists, extremely complex as shown in this video:
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