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Viruses and Monera

Viruses and Monera. Microbiology – study of small life. Virus – “poison”. Alive? – we are not sure. Consensus is they are not alive, they meet some but not all of the traits of life. Why study?. They affect living things, also helps understand difference between life and non-life.

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Viruses and Monera

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  1. Viruses and Monera Microbiology – study of small life

  2. Virus – “poison” • Alive? – we are not sure. Consensus is they are not alive, they meet some but not all of the traits of life

  3. Why study? • They affect living things, also helps understand difference between life and non-life

  4. Composition and Structure

  5. Composition and Structure • Nucleic acid – DNA or RNA, genetic material

  6. Composition and Structure • Protein coat - (capsid) surrounds and protects the nucleic acid

  7. Composition and Structure • Envelope – additional protective coating, contains spikes that bind to sites on a cell

  8. Classification Shape Host they infect How they function

  9. Shape – the arrangement of proteins in capsids

  10. Helical • RNA coils tightly inside the long, narrow capsid

  11. Binal • Two parts, polyhedral capsid and a helical tail

  12. Polyhedral • Multifaceted geometric appearance Adenovirus is one that causes colds

  13. Filovirus • No distinct shape, threadlike or looped at end

  14. What shape is it?

  15. What shape is it?

  16. What shape is it?

  17. What shape is it?

  18. Host – who they infect

  19. Animal • infect only animals

  20. Plant • Infect only plants

  21. Bacteria • (bacteriophages) Infect only bacteria

  22. Other • Can infect many different hosts or only certain species of that host

  23. Function • How they behave or work inside a host Normal viruses and Retroviruses

  24. Retrovirus • “reverse” virus, turns its RNA to DNA

  25. Discovery – found by surprise, looking for the cause of tobacco mosaic disease

  26. Dmitri Ivanovsky • Must be caused by unusually small bacteria or poisons from bacteria Russian Biologist 1892

  27. MartinusBeijerinck • Caused by something smaller than bacteria, an infectious agent he called virus Dutch Biologist 1897

  28. Still unsure where viruses came from, but have discovered many diseases since that have been caused by viruses

  29. Viral Diseases in Humans: • Common cold

  30. Viral Diseases in Humans: • Measles infection of the respiratory system, spread through air, fever, cough, red eyes, rash

  31. Viral Diseases in Humans: • Warts

  32. Viral Diseases in Humans: • AIDS Auto immune deficiency syndrome – spread through body fluids or blood

  33. Viral Diseases in Humans: • Mono Spread through saliva or mucus, fatigue, swollen lymph nodes, enlarged spleen

  34. Viral Diseases in Humans: • Polio damage the nervous system and cause paralysis Enters mouth by contaminated hands with feces

  35. Viral Diseases in Humans: • Viral pneumonia Inflammation of the lungs, cough with mucus, fever, chills

  36. Viral Replication – do not reproduce, no cell division, need a host

  37. Host • An organism that shelters and nourishes something

  38. Lytic Life Cycle • Virus rapidly kills the host cell (lyses = break apart)

  39. Lytic Life Cycle • Attachment – virus sticks to cell and enzymes eat a hole in host cell membrane

  40. Lytic Life Cycle • Entry – viral DNA enters host cell and takes control

  41. Lytic Life Cycle • Replication – viral DNA instructs host to make copies of itself and protein coats

  42. Lytic Life Cycle • Assembly – viral parts are put together to form new viruses

  43. Lytic Life Cycle • Release – host cell bursts releasing new viruses

  44. Then it all starts again… But sometimes…

  45. Lysogeniccycle • Virus doesn’t immediately kill the host cell

  46. Lysogenic cycle • Attachment – virus sticks to cell and enzymes eat a hole in host cell membrane

  47. Lysogenic cycle • Entry – viral DNA enters host cell and inserts into chromosomes

  48. Lysogenic cycle • Replication – host cell divides, replicating viral DNA with own DNA

  49. Lysogenic cycle • Stimulus – something causes the viral DNA to separate from chromosome and enter Lytic cycle Without a stimulus, the viral DNA stays dormant in the cell’s chromosomes

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