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Bacteria and Viruses

Bacteria and Viruses. Lecture Notes for May 12, 2011. Bacteria. Are prokaryotes - do not have a nucleus & membrane-bound organelles. Are placed in either kingdom Eubacteria or kingdom Archebacteria All bacteria are single cells . Some bacteria can stick together or may form strands.

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Bacteria and Viruses

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  1. Bacteria and Viruses Lecture Notes for May 12, 2011

  2. Bacteria • Are prokaryotes- do not have a nucleus & membrane-bound organelles. • Are placed in either kingdom Eubacteria or kingdom Archebacteria • All bacteria are single cells. Some bacteria can stick together or may form strands.

  3. Bacterium Shapes • Cocci~ Sphere-shaped bacteria • Bacillus~ Rod-shaped bacteria • Spirillium ~ Spiral-shaped bacteria

  4. Bacteria and their energy • Autotrophs • Chemotrophs • Heterotrophs

  5. Autotrophs • Photosynthesis- use sunlight to make their food. Four major groups w/ different photosynthetic pigments: a. Purple sulfur (O2 free environment) b. Purple non-sulfur c. Green sulfur (O2 free environment) d. Cyanobacteria (Blue-green alage)

  6. Cyanobacteria • Bluish-greenish color • Carry out the process of photosynthesis • Do not contain the same type of chloroplastsas plants do • Can survive in extremely hot environments and even extremely cold environment

  7. Chemoautotrophs • Make their own food • Remove e-’s from inorganic molecules such as ammonia & methane • Live in the soil & are responsible for nitrification • Ex: Nitrobacter • Ex: Archaebacteria

  8. Heterotrophs • Obtain their own food • Decomposers- break down the bodies of dead organisms • Ex: Rhizobium–live in lumps on legume roots. • Ex: E-coli O157:H7- eats undigested nutrients in mammal intestines

  9. Bacteria Structure: Cell Walls • Two types of cell walls distinguished by Gram staining: Gram – or Gram + • After staining, the color for Gram – is Red & Gram + is Purple. • Gram stain helps determine which antibiotic would be most helpful in fighting an infection.

  10. Gram + and Gram – Bacterium Cell Walls

  11. Movement of Bacteria • Flagella ~ Tail like structure the whips around to propel the bacterium • Cillia ~ Miniature flagella surround the cell that help to “swim” • Pili ~ short hair-like protein structures that help it to stick to surfacces

  12. E. coli with pili Ciliaof a bacterium

  13. Bacteria Reproduction • Binary Fission • Steps of Binary Fission: - DNA condenses to form a circular chromosome & it attaches to the cell membrane. - The DNA is copied, resulting in 2 identical chromosomes (which are both attached to the cell membrane)

  14. Continuation of Reproduction • The cell grow until it reaches TWICE the original size. • The cell begins to divide and a new cell wall forms around the new cell membrane. • The result are two identicaldaughter cells.

  15. Conjugation • Two bacteria swap genetic information, • Enables bacteria to spread genes within a population • Ex: a gene that allows resistance to penicillin

  16. Spore Formation: Endospore • A type of dormant cell • Exhibit no signs of life • Highly resistant to environmental stresses such as: - High temperatures - Irradiation - Strong acids - Disinfectants

  17. Obligate Anaerobes Facultative Anaerobes Obligate Aerobes Live without Oxygen Can live with or without oxygen Cannot live without oxygen. Bacteria Respiration

  18. Parasitism • Bacteria exploit the host cell, injuring them • Eg. Mychobacterium tuberculosis

  19. What are Viruses? A virus is a non-cellular particle made up of genetic material and protein that can invade living cells.

  20. The Structure Of a Virus • Viruses are composed of a core of nucleic acid made of either DNA or RNA but never both. • The nucleic acid core is surrounded by a protein coat called a capsid. • Viruses are classified by differences in the structures of protien coats.

  21. T4 Bacteriophage

  22. Polyhedral Virus Herpes zoster virus

  23. Rod-shaped viruses • Tobacco Mosaic Virus- damages tobacco crops

  24. Rod- shaped Viruses Ebola virus

  25. Are viruses living or nonliving? • They have genetic material that is passed on to future generations • This material can change over time, therefore viruses can evolve • BUT, viruses are not made of cells, they cannot make proteins, cannot use energy (no metabolism), and cannot reproduce.

  26. Multiplication of a Bacteriophage The virus hijacks a living cell’s nucleus. Inserts it’s genetic material into the cell’s DNA. So the cell produces about 100 virus particles in 20 minutes.

  27. Cycle of Lytic and Lysogenic

  28. THE END

  29. Vaccines • Viruses grown on chicken embryos are attenuated vaccines • Another type of vaccine is made by heat killing the virus

  30. Retrovirus • Change DNA into RNA. • Example of a Retrovirus is HIV

  31. A typical, "minimal" retrovirus consists of: • an outer envelope which was derived from the plasma membrane of its host • many copies of an envelope protein embedded in the lipid bilayer of its envelope • a capsid; a protein shell containing • two molecules of RNA and • molecules of the enzyme reverse transcriptase

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