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Bacteria & Viruses

Bacteria & Viruses. Prokaryotes: Smallest and most common microorganisms. Singled celled organisms that lack a nucleus (& membrane bound organelles). Classifying Prokaryotes. For many years, bacteria were in a single Kingdom called “ Monera ”. Now, two separate Kingdoms.

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Bacteria & Viruses

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  1. Bacteria & Viruses • Prokaryotes: Smallest and most common microorganisms. • Singled celled organisms that lack a nucleus (& membrane bound organelles).

  2. Classifying Prokaryotes • For many years, bacteria were in a single Kingdom called “Monera”. • Now, two separate Kingdoms.

  3. Identifying Prokaryotes • Identified by their shape, chemical make-up of their cell walls, how they move, and how they obtain energy. • Shapes: Coccus, Bacillus, & Spirillum. • Arrangements: Diplo-, Staphylo-, and Strepto-

  4. Identifying by Cell Walls • Use a “Gram Staining” method. • If the cell wall contains peptidoglycan, it will absorb the violet colored die. • Known as “Gram-positive”

  5. Identifying by Cell Walls • If the OUTER cell wall does NOT contain peptidoglycan (they have a 2nd, outer layer), they stain pink. • Known as “Gram-negative”

  6. Movement of Bacteria • Some are propelled by flagella. • Whip-like extensions of the cytoplasm.

  7. Movement of Bacteria • Others lash about, slither (like a snake), or spiral forward. • Some move along on a slime-like trail. • Some do not move at all.

  8. Obtaining Energy • Autotrophs: • Photoautotrophs: photosynthesis similar to plants. • Chemoautotrophs: get energy from chemical reactions involving ammonia, sulfur, hydrogen sulfide, etc…

  9. Heterotrophs • Most prokaryotes are heterotrophs. • Most compete with US for food. • Food poisoning comes from the bacteria Staphylococcus aureus. • Food that is handled or prepared improperly and contaminated.

  10. Releasing Energy • Obligate Aerobes: Require a constant supply of O2 to stay alive. • Obligate Anerobes: CANNOT live in the presence of oxygen. O2 is poison! • Facultative Anaerobes: Do not require O2 to live, but they are not poisoned by O2 either.

  11. Growth & Reproduction • In favorable conditions, prokaryotes can grow and divide every 20 minutes. • Warmth, moisture, food, (and space). • Use “Binary Fission” to divide. • Cell divides in two. • NOT MITOSIS (since they do NOT have a nucleus)

  12. Growth & Reproduction • Conjugation allows bacteria to exchange genetic material. • Form of sexual reproduction. • Increases genetic diversity in the population • Endospores may form if conditions are unfavorable for growth. • Can remain dormant for months, even years.

  13. Bacteria in Nature • Vital to maintaining the living world. • Producers • Consumers (includes the Nitrogen Fixers) • Decomposers

  14. Bacteria in Nature • Decomposers: Recycle the raw materials from dead organisms back into the environment.

  15. Bacteria in Nature • Decomposers: Critical component for sewage treatment. • Break down complex compounds into simple ones.

  16. Nitrogen Fixers • Plants and Animals depend on Nitrogen. • Amino Acids, Nucleic Acids, Proteins, etc… • Must be “fixed” from atmospheric N2 into a usable form. • Certain bacteria can convert N2 into Nitrates (NO3) • Live on the roots of certain plants (like legumes).

  17. Bacteria & Disease • Cause disease in two general ways: • 1- Damage Tissue • Grow in or on your body and break down your body tissues, such as tuberculosis & flesh eating bacteria.

  18. Bacteria & Disease • 2- Release Toxins (poison) • Bacteria grow and their waste is toxic to our body. • Typical of food poisoning & strep throat.

  19. Human Uses of Bacteria • Foods: Cheese, pickles, sauerkraut, yogurt. • Industry: Clean up oil spills, waste removal, drug production, and mining.

  20. Human Uses of Bacteria • Biotechnology: Heat stable enzymes, medicines, food production.

  21. Controlling Bacteria • Sterilization: destroys bacteria with heat, chemicals, or radiation. • Refrigeration: Slows bacterial growth in low temperatures.

  22. Controlling Bacteria • Canning: Heat food to high temperatures and seal the container. • Preserve Food: Salting, pickling, drying, etc…

  23. Viruses • Virus-from the Latin word for “poison”. • Have been studied for over 100 years. • -A virus is so small that literally 1 million could fit on the head of a pin.

  24. Viruses (cont.) • Under high power (400 X) a bacteria appears as a dot (.) • The head of a pin would appear as large as the word “dot” • Approximately 20 viruses could fit inside of that dot (.)

  25. Structure of Viruses • Not a cell. • Nucleic acid core surrounded by a protein coat (capsid). • Some have an additional coating called an envelope.

  26. Structure of Viruses (cont.) • 1935: Wendall Stanley isolated the Tobacco Mosaic Virus.

  27. Structure of Viruses (cont.) • Has “spikes”, and other chemical receptors, to chemically recognize an appropriate host.

  28. Structure of Viruses (cont.) • Various shapes and sizes • sizes range from 20 to 400 nm • (0.00000002 m to 0.0000004 m) • one nm is 10-9 m , or one billionth of a meter

  29. Specificity/Infections • Plant viruses only infect plants, animal viruses only infect animals, bacterial viruses only infect bacteria, etc…

  30. Lytic Infection • Virus enters a cell, reprograms the cell’s DNA to make copies of the virus, and causes the cell to burst.

  31. Lysogenic Cycle • Virus enters a cell, reprograms the cell’s DNA (but remains dormant). • Every time the cell replicates, it will also replicate the viral DNA. • After a period of time, the virus becomes active.

  32. Lysogenic Cycle

  33. Diseases • Viruses are responsible for lots of human diseases. • Retroviruses (HIV)- replicate DNA from RNA (backwards). • Viroids (plant) • Prions (animal)-mad cow disease, also some degenerative human brain diseases.

  34. Alive or Non-living? • Some living characteristics. • Nucleic acids, proteins, can reproduce (although not by cell division), can evolve. • Non-living- outside of the host, viruses exhibit no living characteristics. • Cannot move, grow, reproduce, respire. • Are merely inactive chemical particles.

  35. Are they pre-living cell material? • Any hypothesis must include the facts: • 1- Depend totally upon living things. • 2- Infect only a few specific hosts. • 3- Genetic material is similar to the host, and not other viruses. • Some viral genes are almost identical to their host. Must have co-evolved with living hosts.

  36. Protista • Monera: Prokaryotic organisms • Plantae: Eukaryotic, autotrophic, multi-cellular, have a cell wall. • Animalia: Eukaryotic, heterotrophic, multi-cellular, do not have a cell wall. • Fungi: Eukaryotic, heterotrophic, multi-cellular, have a cell wall • What is the Kingdom Protista?

  37. “None of the Above” • Eukaryotic, autotrophic or heterotrophic, mostly single-celled, but some are multi-cellular, may or may not have a cell wall. • Eukaryotic organisms that are NOT members of the Kingdoms Plantae, Animalia, or Fungi.

  38. Protista: Greek for “The Very First” • Lyn Margulis’s “Endo-Symbiotic Theory” • First Eukaryotic life on Earth was most likely the Protists. • Classified several ways. • Movement • Nutrition VonLeuwenhoek: “Cavorting Beasties”: Little Monsters dancing merrily about.

  39. Animal-Like Protists: Protozoans • Zooflagellates: Swim using flagella. • Euglena:

  40. Animal-Like Protists: Protozoans Sarcodines: Literally means “Creeping Flesh”. Use “pseudopods” for feeding and movement. -Pseudopod means “false foot”.

  41. Animal-Like Protists: Protozoans • Ciliates: Use cilia (short hair-like projections similar to flagella) for feeding and movement. • Paramecium:

  42. Animal-Like Protists: Protozoans • Sporozoans: Parasites that do not move on their own. • Complex life-cycles that require more than one host. • Plasmodium: (malaria)

  43. Plant-Like Protists: Algae • Contain chlorophyll and carry out photosynthesis. • Closely related to plants. • Clhorophyll a and b. • Cellulose in cell wall. • Spirogyra:

  44. Plant-Like Protists: Algae • Euglenophytes: Have flagella (can move) and no cell wall. • Characteristics of both plant- and animal-like protists!

  45. Plant-Like Protists: Algae • Dinoflagellates: • Bioluminescent (glow in water). • Chrysophytes: Gold-colored chloroplasts. • Diatoms: Cell wall made of silica (glass!).

  46. Diatom Art!

  47. Plant-Like Protists: Algae • Red Algae: Rhodophyta (killer red tides) • Brown Algae: Phaeophyta (kelp) • Green Algae: Chlorophyta • Most similar to modern land plants.

  48. Human Uses of Algae • Produce over half of the Earth’s oxygen. • Rich in Vitamin C and Iron. • Extract for medicines, vitamins, and supplements. • Thickener for ice cream. • Used in Sushi.

  49. Fungus-Like Protists • Heterotrophic organisms that absorb nutrients from dead, and decaying, organic matter. • Do not have chitin in their cell walls like true fungus.

  50. Great Potato Famine • Ireland (1845) • More than 1,000,000 people starved. • 1.5 million immigrated to the U.S.

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