Viruses and Bacteria
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Slide 1 - Viruses and Bacteria
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
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
Slide 4 - Reproduction of Viruses
- Cannot reproduce alone
- Can reproduce ONLY inside a living host cell
- Must use a host cell
- Like a parasite
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
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.
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.
Slide 8 - Viruses Contain:
- An inner core of DNA or RNA
- An outer protein coat
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.
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.
Slide 11 - Viruses are Highly Specific
Slide 12 - Diseases Caused by Viruses
- Common cold
- Influenza (Flu)
- Caused by the Human Immuno-deficiency Virus (HIV)
- Attacks the immune system (Helper T Cells)
- Helper T Cells
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-
- 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).
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.
Slide 15 - Bacteria
- Bacteria are helpful and harmful organisms
- 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
- Some bacteria cause disease (~½ of all human diseases are caused by bacteria)
- Pathogen – Disease causing agent
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
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
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.
Slide 19 - Types of Bacteria
Slide 20 - Diseases Caused by Bacteria
- Dental Plaque (film destroys tooth enamel)
- Strep Throat
- Diphtheria (causes a false membrane to form in the respiratory system which blocks air passages)
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.
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!
Slide 23 - How to Prevent or Inhibit the Growth of Bacteria
- Sterilization destroys all bacteria by subjecting them to great heat. Most bacteria cannot survive high temperatures for a long time.
- 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.