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Viruses and Bacteria

Viruses and Bacteria. Viruses: Section 19-2. History of Viruses. Iwanowski and Beijernick (1890’s) Worked on Tobacco Mosaic Virus (infects tobacco and tomato leaves). Creates mosaic pattern on leaves.

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Viruses and Bacteria

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  1. Viruses and Bacteria Viruses: Section 19-2

  2. History of Viruses • Iwanowski and Beijernick (1890’s) • Worked on Tobacco Mosaic Virus (infects tobacco and tomato leaves). • Creates mosaic pattern on leaves. • Made a juice of the infected leaves and then put this juice through a filter. Rubbed the filtered juice onto leaves. Still became infected. Concluded that whatever these disease causing particles were, they were very small (smaller than bacteria). • Named them viruses meaning “poison”.

  3. History of Viruses • Stanley (1935) • Purified TMV into a crystal. • Living particles don’t crystallize therefore, viruses are non-living pathogenic (disease causing) particles.

  4. Viruses • Particles of nucleic acid, protein and sometimes a lipid envelope. • Obligate intracellular parasite (can only replicate within a living cell)

  5. Structure of a Virus • Small – 20nm (polio virus) – 350nm (small pox virus) • Single type of nucleic acid (RNA or DNA but never both) • Protein coat – capsid • Some have envelopes (made of lipids)outside of capsid • Surface projections made up of lipids for attachment onto host cells • Are specific to their host

  6. Structure of a Virus

  7. PROCESS BOX 19-1 Based on the information provided, explain why viruses are not considered living WRITE AT LEAST 3 LINES

  8. Viral Shapes • Shapes are • Rod • Helical • Icosahedral (20 sides)

  9. Bacteriophage • Infect E. coli bacteria • Attach with tail fibers onto cell. • Inject nucleic acid into cell

  10. The Lytic Cycle • Get in, replicate and get out to invade other host cells • Virulent (Disease causing) • The cold, rubella (German measles), mumps Release Attachment at Receptor site Entry Assembly Replication

  11. The Lytic Cycle of Virus infection Attaches onto host cell Injects DNA into host cell Replication of Viral parts Reassembly of virons Lysis – bursting out Viruses that reproduce only by the lytic cycle are called Virulent

  12. PROCESS BOX 19-2 In your own words, describe the process of the lytic cycle, and include why it could be seen as “DNA hijacking” WRITE AT LEAST 4 LINES

  13. Lysogenic Infection • Virus embeds its DNA into hosts DNA which is replicated with host cell’s DNA. • Remains unnoticed for sometimes years • AIDS, cold sores, chicken pox, hepatitis Prophage Attachment Integration Cell multiplication & Injection of nucleic acid Prophage remains unnoticed and not transcribed

  14. PROCESS BOX 19-3 In what ways are the lytic and lysogenic cycles similar? In what ways are they different? WRITE AT LEAST 3 LINES

  15. Viral Diseases • Measles, Mumps, Rubella, Rabies, the Cold, the Flu, Influenza, Hepatitis, AIDS, Chicken pox, Small pox, Polio, Yellow fever, Meningititis, some cancers • Vaccines are small doses of either killed, altered or live viruses. Body builds up antibodies against virus

  16. Diseases Caused by Viruses • AIDS • The Cold • Measles • Mumps • Rubella • Chicken pox/Shingles • Small Pox • Hepatitis • SARS • The Flu • Ebola • HPV • Bird Flu • Polio

  17. The Different Forms of Viruses • Retroviruses – AIDS. Contains RNA instead of DNA. Goes from RNA to DNA to RNA to protein. Normal is DNA to RNA to protein. • Viroids – another disease causing agent but no capsid, only the RNA. • Found only in plants • Prion – viral proteins that cause diseases. Scrapie in sheep degrades nervous system. Mad Cow disease (Bovine spongiform encephalopathy) in cows – puts holes into brain. • In humans, its Creutzfeld-Jakob disease & Kuru.

  18. Viruses and Bacteria Bacteria: Section 19-1

  19. Bacterial sizes • Prokaryotesrange from 1-5 μm • Exception: • Epulopisciumfisheloni is 500 μm!

  20. Classification • Old system • One kingdom: Monera • New system • 2 kingdoms • Eubacteria (Domain Bacteria) • Archaebacteria (Domain Archaea)

  21. Archae is more like us (Eukarya) because we share key genes

  22. Bacillus (pl bacilli) Rod-shaped Coccus (plcocci) Spherical Spirillum (plspirilla) Spiral-shaped Bacteria Shapes

  23. PROCESS BOX 19-4 How are these shapes similar? How are they different? What tricks will you use to remember which term goes with each shape/picture? WRITE AT LEAST 3 LINES

  24. Cell Wall • Gram staining can be used to differentiate bacteria • Thick wall of peptidoglycan—purple color • Thin/no wall—pink/red color anthrax gonorrhea

  25. Identify it!

  26. Identify it!

  27. Identify it!

  28. Identify it!

  29. Nonmotile Flagella Movement Escherichia aurescens Escherichia coli

  30. Spiral movement Glide on slime Movement Spirillum volutans Myxobacterium

  31. Metabolism • Bacteria can be either heterotrophic or autotrophic • Heterotrophic—does not produce own food source • Autotrophic—does produce own food source

  32. Heterotroph types • Chemoheterotrophs- take in organic molecules for energy and carbon source • EX: E. coli • Photoheterotrophs- photosynthetic, but needs organic molecules for a source of carbon

  33. Autotroph types • Photoautotrophs- use light energy to convert CO2 and water into organic compounds and O2 • EX: cyanobacteria— “blue green algae” • Chemoautotrophs- make organic molecules from CO2 but use chemical reactions instead of light • Live deep in ocean vents

  34. Releasing energy • Obligate aerobes—need O2 to live • Ex Mycobacterium tuberculosis • Obligate anaerobes—die with O2 • Ex Clostridium botulinum • Facultative anaerobes—either or • Ex E. coli

  35. PROCESS BOX 19-5 Create a graphic organizer that includes heterotroph, autotroph, chemoheterotroph, chemoautotroph, photoheterotroph, obligate aerobe, obligate anaerobe, facultative anaerobe

  36. Growth and Reproduction • Binary fission—grow, double cellular components, and divide

  37. Growth and Reproduction • Conjugation– hollow bridge forms so that bacteria can exchange genetic material

  38. Growth and Reproduction • Spore formation– bacteria can form spores when growth conditions become bad (too hot/cold, too dry, no food) • Protective barrier • When conditions are good again, bacteria will grow again

  39. PROCESS BOX 19-6 Why is it important for bacteria to have multiple “reproductive” strategies? WRITE AT LEAST 2 LINES

  40. Importance of bacteria • Decomposers- • Nitrogen Fixers- • Human uses-

  41. Will you take him home?

  42. Section 19-3 Diseases Caused by Bacteria and Viruses

  43. What is a pathogen? • Okay, now the bad. Name the two ways bacteria cause disease in living organisms. • How can bacterial diseases be prevented?

  44. How can they be treated? • Make a list of human diseases caused by bacteria. • What does it mean to sterilized a substance?

  45. How can we prevent bacteria from spoiling our food? • What do viruses do to us to produce disease? • How are viral diseases treated and prevented?

  46. What is non-effective at treating viral diseases? • List 9 diseases caused by viruses inhumans • How are most plant diseases spread?

  47. 13. What is a prion? 14. Why are viruses not considered to be alive?

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