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Bacteria and Viruses

Bacteria and Viruses. p. 137 in ILL 6/1/12. Bacteria. Characteristics Oldest forms of life on Earth Single- celled organisms Prokaryotic—no nucleus Contain DNA

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Bacteria and Viruses

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  1. Bacteria and Viruses p. 137 in ILL 6/1/12

  2. Bacteria • Characteristics • Oldest forms of life on Earth • Single- celled organisms • Prokaryotic—no nucleus • Contain DNA • Most are consumers and eat other organisms for food, many are decomposers, some live in or on the body of other organisms, and some are producers

  3. Bacteria • Shape • Most have rigid cell walls that give shape • Bacteria come in one of 3 shapes rod (bacilli), sphere (cocci), or spiral (spirilla)

  4. Bacteria • Reproduction • Bacteria can reproduce quickly by a process called binary fission. • Their reproduction is slowed down by cold (refrigeration or freezing), heat (pasteurization and sterilization), and salting.

  5. Bacteria • Role in the World • Good for the Environment • Nitrogen cycle • Decomposition • Good for the People • In food…cheese, yogurt, buttermilk, sour cream, etc. • Medicines…fighting other bacteria, antibiotics, insulin • Genetic Engineering…change genes of bacteria to make insecticides, cleansers, adhesives, etc

  6. Bacteria • Role in the World continued… • Harmful Bacteria (infectious disease) • Pathogenic (disease causing)…tuberculosis, Lyme disease, MRSA, leprosy, strep, etc. • Can be treated with antibiotics--medicines taken by an infected person to kill the bacteria in the body (penicillin, amoxicillin, tetracycline) • Some antibiotics have been overprescribed and by natural selection, bacteria have become resistant (can’t be killed) to certain medications. This is known as antibiotic resistance.

  7. Bacteria

  8. Bacteria • Role in the World continued… • Harmful Bacteria (Infectious disease) • Can also be treated with vaccinations—substances that stimulate the body to produce chemicals (antibodies) that destroy familiar invaders

  9. Viruses • Characteristics/Reproduction • Viruses are neither living nor dead • They are non-cellular • Viruses are significantly smaller than bacteria (5 billion virus particles can fit in a single drop of blood) • Do not use energy, need food or create waste • Contain DNA and protein coat • Can only reproduce inside a host cell which it often destroys • Can add their genetic material to a host cell that stays inactive for a very long time

  10. Viruses • Shapes • Four main shapes: crystals, spheres, cylinders and spacecraft

  11. Viruses • Role in the World • Good for the Environment • Population control…limiting factor • Good for People • Can be manipulated to create medicines and treat some diseases (very new technology)

  12. Viruses • Role in the World continued… • Harmful Viruses (infectious disease) • Pathogenic (disease causing)…HIV, Hepatitis A, B, & C, Chicken Pox, Small Pox, Ebola, Rabies, Swine Flu, Influenza, Common Cold, etc. • Cannot be cured with medications…only symptoms can be treated • Many can be prevented with vaccinations (like bacterial infections)

  13. Viruses

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