Viruses

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					                  Viruses
• Acellular
    Viruses are not made up of cells.
• Need a host
    Must replicate (reproduce) inside a
    living cell.
• Generally very small and cause disease.
  • Two main parts:
     • Capsid - outer covering of protein.
     • Inner core - nucleic acid (DNA or RNA)
       Replication of Viruses
• Attachment
  • spikes allow viruses to bind only to specific host cells.
• Invasion
  • after virus enters the host cell, the capsid breaks open
    and the virus’s DNA or RNA is released.
• Replication
  • host cell’s enzymes make many copies of the virus.
• Building
  • viral proteins and nucleic acid copies are assembled to
    form new viral particles.
• Release
  • host cell bursts releasing new viruses.
Host cell bursts releasing the new
              viruses
Lytic Cycle
Virus invades cell,
replicates, and new
viruses get released
right away.
  Chicken Pox
  Measles
  Influenza
  Cold
  H1N1
Lysogenic Cycle
  After the virus invades,
  the host cell divides
  many times making
  copies that are also
  infected. Then in time,
  the rest of the cycle
  continues.
         Herpes
         Hepatitis B
         HIV
         Syphilis
         HPV
            Bacteriophages
• A type of virus that
  infects bacteria
                Viruses
• Is there a


 CURE
 for viruses?
                      Bacteria
• Bacteria
  •   Much larger than viruses and are Prokaryotes.
  •   Are cells but do not have a nucleus
  •   Have a single circular strand of DNA
  •   Reproduce asexually by binary fission
                 Bacteria
• Grouped according to shape.
  • Cocci—round-shaped bacteria.
  • Bacilli—rod-shaped bacteria.
  • Spirilla – curly-que like a spiral
         Controlling Bacteria
• Washing
• Disinfectants
• Food Storage
  – refrigeration
• Food Processing
  – Boiling, frying, steaming
• Sterilization
  – Medical instruments
     Bacteria – Good or Bad?
• Bacteria produce disease in 2 ways
    -Damaging host tissue
          -bacteria reproduces inside a host
          cell, uses up all of the cell’s
          resources and then ruptures the
          cell when the copies of the
          bacteria bust out
    -Releasing Toxins
          -poisons that cause the disease
    Bacteria – Good or Bad?
• Do most bacteria cause disease?
  – NO! a few bad apples give them a bad name
    Bacteria – Good or Bad?
• Can bacteria be used to help mankind?
  – YES! We use them to produce insulin and
    growth hormone
     Bacteria – Good or Bad?
• Can the world survive without bacteria?
  – NO! we need them to breakdown dead
    organic material and return the nutrients to
    the soil
        Bacterial Reproduction
• Binary Fission
  – The bacteria copies its
    DNA and then splits into
    two identical cells
  – Some bacteria also
    contain an endospore to
    protect its DNA from fire
    or drought, allowing it to
    remain dormant during
    times of reduced resource
    availability. (hard times)
      Bacterial Reproduction
• Conjugation
  – One bacterial cell
    donates a copy of the
    plasmid to another
    bacterial cell
               Antibiotics
• Medications that block the reproduction
  and growth of bacteria.

• Designed to disrupt the bacteria cell but
  not the human cell.
          Antibiotic resistance

• Bacteria become immune to the effects of
  antibiotics (mutates quickly)
• Why?
  – If the full prescription of antibiotics is not
    taken, some of the stronger bacteria survive
    and then reproduce clones. These clones are
    also immune to the antibiotic.
  – Now the antibiotic will not kill this stronger
    type of bacteria.
           Bacterial Diseases
•   Strep throat
•   Pneumonia
•   Necrotizing Fasciitis
•   Lyme Disease
•   MRSA
•   Tuberculosis
•   Food Poisoning
                   Fungus
• Fungi (Singular: fungus)
  – A fungus is neither a plant nor an animal. It is
    similar to a plant, but it has no chlorophyll and
    cannot make its own food like a plant can
    through photosynthesis. They get their food
    by absorbing nutrients from their
    surroundings. (They are decomposers)
     Examples:
        – Yeast, mold, mildew, mushrooms
            Fungal Disease
Mycoses—diseases caused by fungi.
  • Tineas - found in soils, on surfaces, and on
    pets. (Ringworm, Jock-itch, Athlete’s foot)
        Activities of Microbes
• Ecological Contributions - nutrient cycling.
  • Decay - bacteria and fungi break down the remains of
    dead organisms into nutrients.
  • Without decomposing microbes, the biosphere,
    including ourselves, would cease to exist.
     Activities of Microbes
• Economic and Aesthetic Contributions
  • Microbial action - beer, bread, wine, yogurt,
    butter, and cheese.
  • Microbial metabolism - vitamins, antibiotics,
    insulin, and enzymes used in detergents.
      Activities of Microbes
• Contributions of Our Health—normal
  microflora inhabit our bodies and
  prevent the invasion of pathogens.
  (Symbiosis)
      Modes of Transmission
       (How do you get it)
• Direct Contact
   – contact with body fluids or lesions of the infected
     person.
• Airborne
   – microbes travel in droplets of saliva or can survive for
     long periods of time in dust. (cough, sneeze)
• Vehicle
   – Contaminated food, cell phones or sharing a soda
     can transmit many diseases.
• Vector-borne
   – an animal that carries disease from one host to
     another. (ticks, mosquitoes, rabid dogs)
22-6
What Causes Your Symptoms?
•   Sore throat – killed cells
•   Diarrhea – body’s way of kicking it out
•   Fever – make it too hot for the bad guy
•   Redness – dead and damaged cells
•   Itching – dead and damaged cells
•   Swelling – dead and damaged cells
•   Pain – dead and damaged cells
               Prevention
• How can you keep from getting a microbe?

•   Vaccinations
•   Wash Hands
•   Cover coughs and sneezes
•   Don’t share drinks and food
•   Get enough sleep (boosts immune system)
•   Eat healthy foods
•   Vitamins
               Vaccinations
• A preparation of
  weakened or killed
  pathogens or inactivated
  toxins

• When injected into the
  body, a vaccine prompts
  the body to produce an
  immune response to the
  specific disease
         Immune Response
• Vaccinations prevent disease by
  stimulating the production of antibodies.
               Hand Washing
• Use warm water (not cold or hot).
• Use whatever soap you like. Antibacterial soaps are
  popular but regular soap works fine.
• Rub your hands together vigorously and scrub all
  surfaces: Lather up on both sides of your hands, your
  wrists, between your fingers, and around your nails.
  Wash for 15 seconds — about how long it takes to sing
  "Happy Birthday."
• Rinse well under warm running water and pat dry with a
  clean towel.
• When there is no soap or water available, hand
  sanitizers are a good alternative.
• Remember, proper and frequent hand washing is the key
  to preventing the spread of many common infections.
      CDC Recommendations
• Cover your nose and mouth with a tissue
  when you cough or sneeze. Throw the tissue in
  the trash after you use it.
• Wash your hands often with soap and water,
  especially after you cough or sneeze. If soap
  and water are not available, use an alcohol-
  based hand rub.
• Avoid touching your eyes, nose or mouth.
  Germs spread that way.
• Stay home if you get sick. CDC recommends
  that you stay home from work or school and limit
  contact with others to keep from infecting them.

				
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posted:12/9/2011
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