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1. What properties do living organisms?
2. What Nucleic acids you know?
3. What are the functions of nucleic acids?
Viruses (from Latin virus - poison) do not have a cellular structure.
They represent the simplest form of life on our planet, occupying a borderline position between inanimate and living matter.
Viruses differ from inanimate matter in two properties: the ability to reproduce similar forms to themselves (multiply) and the possession of heredity and variability.
Viruses are arranged very simply. Each viral particle consists of RNA or DNA enclosed in a protein coat called a capsid (Fig. 16).
Having penetrated into the cell, the virus changes its metabolism, directing all its activities to the production of viral nucleic acid and viral proteins... Self-assembly of viral particles from synthesized nucleic acid molecules and proteins occurs inside the cell. Until the moment of death, a huge number of viral particles have time to be synthesized in the cell. Ultimately, the cell dies, its membrane bursts and viruses leave the host cell (Fig. 17).
Living in the cells of living organisms, viruses cause many dangerous diseases: in humans - influenza, smallpox, measles, poliomyelitis, mumps, rabies, AIDS and many others; in plants - mosaic disease of tobacco, tomatoes, cucumbers, leaf twisting, dwarfism, etc.; in animals - foot and mouth disease, swine and bird plague, infectious anemia of horses, etc.
Viruses. Capsid.
1. What structure do viruses have?
2. On what basis are viruses classified as living organisms?
3. What features distinguish viruses from other living organisms?
Kamensky A.A., Kriksunov E.V., Pasechnik V.V. Biology Grade 9
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