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Virus Introduction

Virus Introduction. What is a Virus?. A small infectious agent that can replicate only inside the cells of other organisms, bacteria, plants or animals. Consists of at least two of three parts Genetic material, DNA or RNA (retro virus) Protein coat that protects the genetic material

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Virus Introduction

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  1. Virus Introduction

  2. What is a Virus? • A small infectious agent that can replicate only inside the cells of other organisms, bacteria, plants or animals. • Consists of at least two of three parts • Genetic material, DNA or RNA (retro virus) • Protein coat that protects the genetic material • Possible lipid membrane

  3. How do they compare to Bacteria? • They both can cause disease and have a similar structure

  4. Are viruses alive? • Viruses have characteristics that may classify them as living. • They also have characteristics that classify them as non-living • They have no metabolism and cannot reproduce on their own so they do not qualify as a living organism.

  5. How small are viruses? • Viruses are typically 20 – 400 nm • Bacteria are typically 1000 nm

  6. 4Shapes of a virus • Helical

  7. Icosahedral

  8. Envelope

  9. Complex

  10. Virus discovery and origin • In 1884 by French microbiologist Charles Chamberland • Origin is unclear because they do not leave behind any fossils or life evidence • The viruses that have been preserved by scientists date back about 90 years • There are 3 different theories of possible origin

  11. 1. Regressive • Viruses may have been small cells that parasitized larger cells and then lost unnecessary genes • 2. Cellular • May have evolved from bits of DNA, RNA or plasmids that may have escaped or been lost • 3. Coevolution • May have evolved from complex proteins and genetic material at the same time as cells first originated and are dependant on cells to stay in existence

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