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Bacteria & Viruses

Bacteria & Viruses. Prokaryote Review. Mostly single-celled No nucleus or organelles Cell walls Reproduce mostly asexually Anaerobic or aerobic Heterotrophic or autotrophic. Bacteria are named by shape. Rod: bacillus Spheres: coccus Spirals: spirillum. Arrangement. Paired: diplo

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Bacteria & Viruses

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  1. Bacteria & Viruses

  2. Prokaryote Review • Mostly single-celled • No nucleus or organelles • Cell walls • Reproduce mostly asexually • Anaerobic or aerobic • Heterotrophic or autotrophic

  3. Bacteria are named by shape • Rod: bacillus • Spheres: coccus • Spirals: spirillum

  4. Arrangement • Paired: diplo • Grape-like clusters: staphylo • Chains: strepto

  5. Examples • Streptococcus: chains of spheres • Staphylospirillum: Grapelike clusters of spirals • Streptobacillus: Chains of rods

  6. Reproduction of Bacteria • The time of reproduction depends on how desirable the conditions are • Bacteria can rapidly reproduce themselves in warm, dark, and moist conditions • Some can reproduce every 20 minutes • (one bacterium could be an ancestor to one million bacteria in six hours)

  7. Bacteria Survival – Food sources • parasites – bacteria that feed on living things • saprophytes – use dead materials for food (exclusively) • decomposers – get food from breaking down dead matter into simple chemicals • important- because they send minerals and other materials back into the soil so other organisms can use them

  8. Helpful Bacteria • Decomposers help recycle nutrients into the soil for other organisms to grow • Bacteria grow in the stomach of a cow to break down grass and hay • Most are used to make antibiotics • Some bacteria help make insulin • Used to make industrial chemicals

  9. If I were a virus how big would bacteria be?

  10. Viruses Dead or alive?

  11. Viral structure • Viruses are not cells. • Basic structure: • Protein coat • Nucleic acid core (RNA or DNA) • Lipoprotein coat • (second coat – only in enveloped viruses)

  12. Virus Categories • DNA viruses – stable, do not mutate rapidly • Single-stranded or double-stranded • Smallpox, Hepatitis B • RNA viruses – mutate rapidly, unstable • Single-stranded or double-stranded • HIV, Rhinovirus

  13. Are viruses alive? • Only 1 characteristic of life: reproduction • Can only reproduce inside a host cell! • Process or reproduction = lytic cycle

  14. Lytic Cycle • Virus attaches to host cell’s membrane and injects its nucleic acid into the host cell. • The viral nucleic acid takes over protein synthesis, creating new viruses. • The host cell bursts, lyses, releasing the newly formed viruses.

  15. Before attachment Attachment Injection Release Assembly Replication

  16. HIV undermines the body's ability to protect against disease by depleting T cells thus destroying the immune system. • The virus can infect 10 billion cells a day, yet only 1.8 billion can be replaced daily.

  17. After many years of a constant battle, the body has insufficient numbers of T-Cells to mount an immune response against infections. At the point when the body is unable to fight off infections, a person is said to have the disease AIDS. • It is not the virus or the disease that ultimately kills a person; it is the inability to fight off something as minor as the common cold.

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