Viruses and Bacteria


Viruses and Bacteria

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  1. Viruses and Bacteria

    Slide 1 - Viruses and Bacteria

  2. Characteristics of Viruses

    Slide 2 - Characteristics of Viruses

    • Classified as Nonliving
    • Not made up of cells
    • Cannot live independently
    • Do not require food
    • Do not grow or move
  3. Viruses are Nonliving

    Slide 3 - Viruses are Nonliving

    • Viruses are at the borderline of living and nonliving.
    • Do not have all eight characteristics of living things so is classified as nonliving.
    • Characteristics of Living Things
    • 1.)Made up of cells
    • 2.) Must reproduce
    • 3.) Must be based on a universal genetic code
    • 4.) Must grow and develop
    • 5.) Must obtain and use materials and energy
    • 6.) Must respond to their environment
    • 7.) Must maintain a stable environment
    • 8.) Must change over time
  4. Reproduction of Viruses

    Slide 4 - Reproduction of Viruses

    • Cannot reproduce alone
    • Can reproduce ONLY inside a living host cell
    • Must use a host cell
    • Like a parasite
  5. Structure of Viruses

    Slide 5 - Structure of Viruses

    • An inner core made up of nucleic acid
    • Either DNA or RNA
    • Contains the genetic material
    • Outer coat of protein
    • The protein coat gives the virus its shape
  6. Structure of Viruses

    Slide 6 - Structure of Viruses

    • Capsid – A viruses’s protein coat.
    • Includes proteins that enable a virus to enter a host cell.
    • Bind to receptors on the surface of a cell and “trick” the cell into allowing it inside.
    • Envelope - Outer membranous layer made of lipid and protein.
    • Surrounds the capsid in some viruses.
    • Protein spikes of the envelope facilitate adherence and entry into the host cell.
  7. Structure of Viruses (Continued)

    Slide 7 - Structure of Viruses (Continued)

    • Tail Fiber - Structural protein that functions as an anchoring mechanism for the virus to attach itself to the surface of a bacterial cell
    • Only found in viruses (bacteriophages) that infect bacteria.
  8. Viruses Contain:

    Slide 8 - Viruses Contain:

    • An inner core of DNA or RNA
    • An outer protein coat
  9. Viruses are Highly Specific

    Slide 9 - Viruses are Highly Specific

    • HIV infects Helper T cells.
    • Rabies infects brain cells.
    • Different cold viruses attack the cells lining the nose and sinuses.
    • Hepatitis settles in the liver.
  10. Viruses are Highly Specific

    Slide 10 - Viruses are Highly Specific

    • The basic principle of viral infection of a given cell is that if a cell's outer surface contains the receptor to which a virus's attachment protein can bind, the virus will be able to invade and grow in that cell.
  11. Viruses are Highly Specific

    Slide 11 - Viruses are Highly Specific

  12. Diseases Caused by Viruses

    Slide 12 - Diseases Caused by Viruses

    • Common cold
    • Influenza (Flu)
    • Smallpox
    • Warts
    • AIDs
    • Caused by the Human Immuno-deficiency Virus (HIV)
    • Attacks the immune system (Helper T Cells)
    • HIV
    • Helper T Cells
  13. Treatment of Viruses

    Slide 13 - Treatment of Viruses

    • Treatment of virus infections is usually left up to the patient's own immune system.
    • There is no cure for viruses!
    • The only thing you can do is-
    • Rest
    • Drink lots of water
    • Take pain killers
    • May receive a vaccine to prevent from getting the virus if available.
    • A vaccine is a preparation of weakened or killed pathogens (virus or viral particles).
  14. Why isn’t there a cure for viruses?

    Slide 14 - Why isn’t there a cure for viruses?

    • Viruses replicate in the body’s cells.
    • If you destroy the virus, you are destroying your own body cells.
  15. Bacteria

    Slide 15 - Bacteria

    • Bacteria are helpful and harmful organisms
    • Helpful:
    • Cheese, pickles, yogurt, and vinegar are produced as the results of metabolism by certain bacteria
    • Some bacteria produce antibiotics that are used to kill other bacteria
    • Aids in human digestion (E. coli) and other life processes
    • Carry out photosynthesis
    • Decomposers (recycle nutrients)
    • Fix Nitrogen
    • Harmful:
    • Some bacteria cause disease (~½ of all human diseases are caused by bacteria)
    • Pathogen – Disease causing agent
  16. Structure of Bacterial Cells

    Slide 16 - Structure of Bacterial Cells

    • Bacteria are prokaryotes
    • Have no membrane bound organelles
    • Inherited information is held in a single, circular chromosome, rather than in paired chromosomes
    • Bacteria are unicellular (one-celled living organisms)
    • Bacteria contain a cell wall
  17. Structure of Bacterial Cells

    Slide 17 - Structure of Bacterial Cells

    • Some bacteria contain pili
    • extensions of the plasma membrane help bacteria stick to surfaces
    • Bacteria contain flagella
    • enable bacterial cells to move
    • Some bacteria contain capsules
    • prevent bacteria from being easily engulfed
  18. Bacteria are Everywhere!!!

    Slide 18 - Bacteria are Everywhere!!!

    • Bacteria are everywhere!
    • In some of the food you eat
    • In the air you breathe
    • In the water you drink
    • On your skin
    • Inside your body
    • The relationship between most bacteria and the human host is mutualistic.
  19. Types of Bacteria

    Slide 19 - Types of Bacteria

  20. Diseases Caused by Bacteria

    Slide 20 - Diseases Caused by Bacteria

    • Dental Plaque (film destroys tooth enamel)
    • Strep Throat
    • Pneumonia
    • Diphtheria (causes a false membrane to form in the respiratory system which blocks air passages)
    • Acne
  21. Bacteria Cause Disease By:

    Slide 21 - Bacteria Cause Disease By:

    • Damage cells and tissue of the infected organism directly by breaking down the cells for food.
    • Release toxins (poisons) that travel throughout the body interfering with the normal activity of the host.
  22. How to Treat Bacterial Infections

    Slide 22 - How to Treat Bacterial Infections

    • Antibiotics - Compounds that block the growth and reproduction of bacteria.
    • To make sure that you get the right treatment, your doctor may take a sample (a swab from the throat or a urine sample)
    • Do not take antibiotics if you don’t have a bacterial infection. You are only making the bacteria smarter and more resistant!
  23. How to Prevent or Inhibit the Growth of Bacteria

    Slide 23 - How to Prevent or Inhibit the Growth of Bacteria

    • Sterilization
    • Sterilization destroys all bacteria by subjecting them to great heat. Most bacteria cannot survive high temperatures for a long time.
    • Disinfectants
    • Chemical solutions that kill pathogenic bacteria.
    • Overuse of antibacterial compounds increase the likelihood that common bacteria will eventualy evolve to become resistant to them.
    • Food Processing
    • Store food in refrigerator (low temperature = longer for bacteria to multiply)
    • Cooking (boiling, frying, or steaming) raises the temperature of the food to the point that the bacteria are killed.