Viruses and Bacteria
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Viruses and bacteria are microscopic organisms that can cause infection. Viruses are non-living particles that enter and reproduce inside living cells. They come in various shapes and sizes smaller than cells, and have a protein coat and genetic material. Bacteria are single-celled organisms that lack a nucleus and other structures found in more complex cells. They also appear in different shapes and sizes around 0.5-1 micrometer. Both viruses and bacteria can infect and potentially harm their host cells.
Viruses and Bacteria
- 2. Viruses • A tiny, non-living particle that enters and then reproduces inside a living cell • Needs a host, which provides a source of energy • Parasite – Lives on or in a host and can cause harm
- 3. Shapes • Round, rod-shaped, bricks, threads, bullets, robot-like shapes
- 5. Sizes • Smaller than cells • Cannot be seen with school microscopes • Measured in nanometers – 1 billionth of a meter
- 6. Structure • Two basic parts – Protein coat which protects itself – Inner core • Genetic material
- 7. Surface Proteins • Can attach to host cells • Lock and key • Specific
- 8. Multiply • Inside host cell – Virus’s genetic material takes over many cell functions – Instructs cell to produce the virus proteins and genetic material – Make new virus’s
- 9. Bacteria • Anton van Leeuwenhoek (late 1600s) – Scrapings from teeth – Could only see shapes, but not the parts inside the cells
- 10. Bacteria • Prokaryotes – Genetic material is not contained in a nucleus (have no nucleus) – Lack some other structures as well
- 11. Shapes and Sizes • Spherical, rodlike, spiral • Vary in size, average is about 0.5-1 micrometer – 1 millionth of a meter