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Viruses

Viruses. When is a life form not a life form?. When it’s a virus!

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Viruses

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  1. Viruses

  2. When is a life form not a life form? • When it’s a virus! • Viruses are strange things that straddle the fence between living and non-living. On the one hand, if they're floating around in the air or sitting on a doorknob, they're inert. They're about as alive as a rock. But if they come into contact with a suitable plant, animal or bacterial cell, they spring into action. They infect and take over the cell like pirates hijacking a ship.

  3. A virus is basically a tiny bundle of genetic material—either DNA or RNA—carried in a shell called the viral coat (or capsid) Flu virus

  4. What kind of Microbe is it? • Microbes are single-celled organisms that can perform the basic functions of life — metabolism, reproduction, and adaptation.

  5. Except viruses. Viruses can’t metabolize nutrients, produce and excrete wastes, move around on their own, or even reproduce unless they are inside another organism’s cells. HIV Virus

  6. They aren’t even cells. • Diagram of Flu virus

  7. When viruses come into contact with host cells, they trigger the cells to engulf them, or fuse themselves to the cell membrane so they can release their DNA into the cell.

  8. Once inside a host cell, viruses take over its machinery to reproduce. Viruses override the host cell’s normal functioning with their own set of instructions that shut down production of host proteins and direct the cell to produce viral proteins to make new virus particles.

  9. Some viruses insert their genetic material into the host cell’s DNA, where they begin directing the copying of their genes or simply lie dormant for years or a lifetime. Either way, the host cell does all the actual work: the viruses simply provide the instructions. Hiv virus

  10. Viruses may be able to infect and reproduce in more than one kind of animal, but the same virus can cause different reactions in different hosts. • For example, flu viruses infect birds, pigs, and humans. While some types of flu viruses don’t harm birds, they can overwhelm and kill humans. • Plant viruses do not infect animals or vice versa. Viruses that infect bacteria do nothing to animal or plant cells. Swine flu virus

  11. Viruses exist for one purpose only: to reproduce. To do that, they have to take over the reproductive machinery of suitable host cells.

  12. Virus or Bacteria? • Because bacteria and viruses cause many of the diseases we're familiar with, people often confuse these two microbes. But viruses are as different from bacteria as goldfish are from giraffes.

  13. For one thing, they differ greatly in size. The biggest viruses are only as large as the tiniest bacteria.

  14. Another difference is their structure. Bacteria are complex compared to viruses.

  15. A virus may or may not have an outermost spiky layer called the envelope. All viruses have a protein coat and a core of genetic material, either DNA or RNA. And that's it. Period. HIV Virus

  16. Viruses are moochers. They contain only a limited genetic blueprint and they don't have the necessary building tools. They have to invade other cells and hijack their cellular machinery to reproduce. Viruses invade by attaching to a cell and injecting their genes or by being swallowed up by the cell.

  17. These are T4 bacteriophages (back-tear-e-oh-faj-es). They are a kind of virus that infects bacteria. Here they are landing on the surface of an E. coli bacterium.

  18. The bacteriophage cuts a hole in the E. coli's cell wall. It then injects its genetic material into the bacterium. By taking over the E. coli's genetic machinery, the viral genes tell the bacterium to begin making new virus parts. These parts come together to make whole new viruses inside the bacterium. • Eventually so many new viruses are made that the E. coli bursts open and dies, releasing all those new viruses to infect more cells

  19. The way that viruses spread is specific to the type of virus. They can be spread through the following means: • Carrier organisms - mosquitoes, fleas • The air • Direct transfer of body fluids from one person to another - saliva, sweat, nasal mucus, blood, semen, vaginal secretions • Surfaces on which body fluids have dried • Virus Videohttp://www.npr.org/templates/story/story.php?storyId=114075029

  20. Are viruses and bacteria treatable? • Well………… most bacteria are easily treatable with an antibiotic which is prescribed by the doctor. • However………since viruses take over cells in your body, they are not easily treated. Usually it is left up to your immune system to deal with the virus. There are some new antiviral drugs becoming available but only for a few viruses. • The best thing is to avoid getting a virus in the first place.

  21. To reduce the risk of spreading or contacting viruses, here are things you can do: • Cover your mouth or nose when you sneeze or cough. • Wash your hands frequently, especially after going to the bathroom or preparing food. • Avoid contact with the bodily fluids of others. • These practices are not foolproof, but they can help you reduce the risk of viral infection.

  22. Sources • http://www.netdoctor.co.uk/health_advice/facts/virusbacteria.htm • http://www.microbeworld.org/ • http://www.nationalgeographic.com/ • https://eapbiofield.wikispaces.com/Erika+PR+9+Classification?f=print

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