Most viruses are nano-sized and cannot be observed by ordinary microscopes. Under the visible light source, the virus cannot be observed.
Therefore, the virus can only be observed by transmission electron microscope, but not directly by naked eye. The principle of transmission electron microscope is to use high-speed electrons to pass through virus samples and hit the fluorescent screen for imaging.
The basic structure of the virus:
The protein shell of virus is called capsid, and the genetic material is mostly RNA or DNA. Capsules and nucleic acid molecules are collectively referred to as core-shell However, taking HIV as an example, the virus surface is also wrapped with cell membrane and spiny structure similar to cell membrane, which together with capsid * * * determines the specificity of the virus. There are some enzymes, such as reverse transcriptase.
The most common virus consists of protein shell and nucleic acid (DNA or RNA); But prions have no nucleic acid, only protein; There is a virus-like. There is only one nucleic acid without protein.
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