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Viruses

Viruses. Virus Facts. Nonliving particle that invade the cells of plants, animals, fungi, and bacteria. Often destroy the cells they invade Virology is the study of viruses. History of Virology. Wendell Stanley crystallized the tobacco mosaic virus in 1935

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Viruses

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  1. Viruses

  2. Virus Facts • Nonliving particle that invade the cells of plants, animals, fungi, and bacteria. • Often destroy the cells they invade • Virology is the study of viruses

  3. History of Virology • Wendell Stanley crystallized the tobacco mosaic virus in 1935 • Discovered that it may be a chemical rather than a cell

  4. Tobacco Mosaic Virus

  5. Characteristics • No Growth • No Homeostasis • No Metabolism • Can Mutate • May contain DNA or RNA

  6. Characteristics • Can only reproduce in a host cell • Made up of a nucleic acid core, protein coat, and in some cases an envelope • The coat protects the genetic material • Enables the virus to invade its host cell

  7. Virus

  8. Viral Shape • Determined by capsid or its nucleic acid • Icosahedron-20 triangular faces - herpes simplex, chicken pox, polio • Helix - a coiled spring - rabies, measles, tobacco mosaic virus

  9. Icosahedron

  10. Helix

  11. DNA Viruses • Virus may directly produce DNA that then makes more viral proteins • May join with the host cell’s DNA to direct the synthesis of new viruses • Chicken pox, mono, herpes

  12. DNA Viruses

  13. RNA Viruses • Viral RNA is released into the host cell’s cytoplasm • Uses the host cell’s ribosomes to produce new viral proteins

  14. RNA Viruses

  15. Retroviruses • RNA Viruses • Contains an enzyme called reverse transcriptase. • Uses a template to make DNA

  16. Viruses

  17. Viroids and Prions • Viroids - smallest known particles that are able to replicate • Consist of a short, single strand of RNA and has no capsid • Disrupt plant cell metabolism and damage crops

  18. Viroid

  19. Viroids and Prions • Prions - abnormal forms of protein that clump together inside a cell • Clumping kills the cell • Scrapies, Mad Cow

  20. Prion

  21. Viral Replication

  22. Bacteriophage • Viruses that infect bacteria • Viral nucleic acid head, a collar, a sheath, which makes up the tail, together making the capsid. There is also a base plate and tail fibers.

  23. Animation • http://www.hybridmedicalanimation.com/anim_bacteriophage.html

  24. The Lytic Cycle • Destroys the host cell • Attachment • Entry • Replication • Assembly • Release – Released viruses are called progeny

  25. Lysogenic Cycle • These viruses do not destroy the host immediately • Attachment • Injection • Integration • Cell multiplication

  26. Lysogenic

  27. Viruses and Human Disease

  28. Transmission of Diseases • Human contact • Air • Water • Insect bites

  29. Prevention and Treatment • Antiviral drugs • Interfere with viral nucleic acid synthesis • Already infected patients

  30. Prevention and Treatment • Vaccination • Inactivated • Do not replicate in a host system • Attenuated • Genetically altered so they are incapable of causing disease

  31. Emerging Viruses • Newly discovered viruses • Exist in isolated habitats, but infect humans when habitats are developed. • Ebola found in the Democratic Republic of Congo

  32. Viruses and Cancer • Lysogenic viruses may trigger cancer genes • Hepatitis B • Epstein-Barr

  33. Eradication Lysis Capsid More terms to know

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