1. Microbiology Part 2 Bacteria and Viruses

2. Bacteria There are two main types of bacteria: Eubacteria (“true bacteria”) are found everywhere - in the air, on the ground, and in water…even on the page you are writing on now. Archebacteria (“ancient bacteria”) are found only in extreme environments. - for example, places that are intensely hot (sulfur pools, ocean vents), salty (Dead Sea), or acidic (inside digestive tract).

3. Most bacteria are much smaller than plant and animal cells. They are prokaryotic cells. This means they have no nucleus… all the genetic material is just strewn around loose in the cell. Bacteria do contain ribosomes to manufacture protein. Bacteria

4. Some bacteria also contain the pigment chlorophyll and are autotrophs, able to produce their own food through photosynthesis. Some other autotrophic bacteria can use energy from chemicals in their environment to produce their food (chemosynthesis). Most, however, are heterotrophs, consuming a variety of foods, breaking down dead material or living as parasites off a host. Bacteria

5. Almost all organisms on Earth including most bacteria require oxygen to break down food and release energy- they are called aerobic organisms. Some bacteria, however, are adapted to live completely without oxygen and are called anaerobic. These are usually found buried deep in muddy swamps or bogs, in hydrothermal vents in the ocean, or even in the human intestines! Bacteria in soil intestinal bacteria

6. Bacteria in Nature and Industry Bacteria are involved in:  Oxygen and food production  Environmental recycling and cleanup  Health maintenance and medicine production

7.  Autotrophic bacteria use the Sun's energy to produce their food and as a result they release oxygen into the air.  Scientists believe autotrophic bacteria were responsible for adding oxygen to the Earth's early atmosphere and made it habitable for life as we know it.  Today, distant ancestors of those bacteria continue to keep oxygen levels in the air stable. Bacteria in Nature and Industry: Oxygen Production

8.  The activities of helpful bacteria help produce many foods, like soy sauce, sauerkraut, pickles, apple cider and vinegar.  Bacteria that grow in milk help produce dairy products such as buttermilk, yogurt, sour cream and cheeses. Bacteria in Nature and Industry: Food Production

9.  Some bacteria, however cause food to spoil when they break down the food's chemicals.  Refrigeration and heating can slow down spoilage  Another method to preserve food is called pasteurization  Named after its inventor, Louis Pasteur, it involves heating food to a temperature high enough to kill harmful bacteria without changing the flavor of the food. Bacteria in Nature and Industry: Food Production

10.  Some heterotrophic bacteria that live in soil are decomposers - organisms that break down large chemicals in dead organisms into smaller chemicals.  For example, decomposing dead leaves in the fall and winter so the nutrients can be re-used by the plants in the spring Bacteria in Nature and Industry: Environmental Recycling

11.  Nitrogen-fixing bacteria live in the soil and in nodules in the roots of a type of plant called a legume (like peanuts, soy beans and peas).  These helpful bacteria help plants by converting nitrogen from the air into a form of nitrogen plants need to survive. Bacteria in Nature and Industry: Environmental Recycling  Without nitrogen-fixing bacteria, farmers would need to spend millions more on fertilizer each year.

12. Some bacteria can digest oils. They can convert the poisonous chemicals in oil into harmless substances. Scientists use them to help clean-up oil spills in oceans and gasoline leaks in soil under gas stations. Bacteria in Nature and Industry: Bio-remediation (Environmental Clean-up)

13. ◄ There are many bacteria in your body that help keep you healthy. ◄ In your digestive system your intestines teem with bacteria. ◄ Some help you digest food. ◄ Some make vitamins like vitamin K that your body needs. ◄ Others compete for space and resources with disease causing organisms, keeping harmful bacteria from attaching to your intestines, making you sick. Bacteria and Your Health: Natural Flora Bacteria

14. Viruses ∞A virus is a tiny non-living particle that enters and then reproduces inside a living cell. ∞No organisms are safe from viruses, for every different type of cell in every different type of organism, there is a virus able to invade that organism's cells.

15. Viruses: Characteristics  Viruses come in many shapes.  All viruses have two basic parts: a protein coat that protects the virus and an inner core made of genetic material.  Some viruses are surrounded by an additional covering called an envelope.

16.  Each virus contains specific surface proteins.  They are shaped to match a particular host cell.  This explains why each virus has very specific host cells that it is able to infect. Viruses: Characteristics

17. Viruses: How They Multiply ◘ Viruses are considered non-living because they do not show all the characteristics of life. ◘ They are not cells and do not use their own energy to grow or respond to their environment ◘ Although viruses can multiply, they do so differently than organisms. Viruses can multiply only inside a living host cell ◘ A virus acts like a parasite, as almost all viruses destroy the cells in which they multiply.

18. ◘ Once inside a host cell, a virus's genetic material takes over many of the cells functions. ◘ It instructs a cell to produce the virus's proteins genetic material. Viruses: How They Multiply ◘ These then assemble into new viruses ready to infect more host cells.

19. ◘ Active viruses begin production and assembly immediately. ◘ Makes copy after copy of the viruses until the host cell bursts open and new viruses begin infecting neighboring cells. Viruses: How They Multiply

20. ◘ Hidden or latent viruses do not affect the cell right away. ◘ The virus genetic material becomes part of the cell's genetic material. ◘ Each time the host cell divides, the virus genetic material is copied along with the host material. ◘ Then under certain circumstances, the virus's genetic material suddenly becomes active and all of the damaged cells begin producing copies of the virus. Viruses: How They Multiply

21. Viruses In Medicine * Not all news about viruses is bad. * Gene therapy takes advantage of a virus's ability to enter a host cell. * Scientists replace harmful virus genetic material with good genetic material. * They then use the virus as a messenger service to deliver genetic material to cells that need it.

22. Bacteria, Viruses and Your Health Infectious diseases are spread through:  Contact with an infected person  A contaminated object  An infected animal  An environmental source Once contact occurs, disease-causing agents may enter through:  Breaks in the skin  May be inhaled or swallowed  May enter the moist linings of the eyes, nose, mouth or other body openings

23. Treating Infectious Diseases - Bacteria  Luckily, many bacterial diseases can be treated with antibiotics.  An antibiotic is a chemical that will destroy bacteria (usually by weakening the cell wall causing the bacterial cells to burst) without harming a person's cells.

24.  Unfortunately, some bacteria are becoming resistant to antibiotics. As resistant bacteria survive and reproduce the number of resistant bacteria increases.  Today some bacterial diseases are becoming very difficult to treat. Treating Infectious Diseases - Bacteria

25.  Unlike bacterial diseases there are currently no medicines that cure viral infections.  There are many over-the-counter medicines that can help a person feel better.  The best treatment for a virus is usually bed rest. Treating Infectious Diseases - Viruses

26.  Although there is no cure for a virus, a vaccine may be able to prevent a person from getting sick in the first place.  A vaccine stimulates the production of chemicals that destroy specific viruses or bacteria. Treating Infectious Diseases - Viruses

27.  A vaccine may be made from dead or altered viruses or bacteria. Therefore it will not cause a person to become sick.  Instead the vaccine will activate a person's natural defenses putting the body “on alert”. Treating Infectious Diseases - Viruses  So that if the virus or bacterium ever invades the body it is destroyed by antibodies before it can cause the disease.