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Chapter 19

Chapter 19. Bacteria and Viruses. Remember homeostasis?. Maintaining proper internal conditions pH, temp., water/salt balance, O2, CO2, etc. Factors for Disease. 1. genetics- inheritance 2. microorganisms pathogen : disease-causing agent 3. pollutants/poisons (ex: asbestos, lead)

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Chapter 19

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  1. Chapter 19 Bacteria and Viruses

  2. Remember homeostasis? • Maintaining proper internal conditions • pH, temp., water/salt balance, O2, CO2, etc.

  3. Factors for Disease • 1. genetics- inheritance • 2. microorganisms • pathogen: disease-causing agent • 3. pollutants/poisons (ex: asbestos, lead) • 4. organ malfunction • 5. harmful lifestyles (tobacco, alcohol, lack of nutritionor exercise)

  4. 19-1 Bacteria • Prokaryotes • Monera • Can be beneficial or disease-causing • Good: intestinal bacteria • Bad: strep throat, pneumonia • Everywhere!

  5. Identified by: • Shape- bacilli (rod), cocci (round), spirilla (spiral) • Cell walls- Gram +/- (peptidoglycan) • Movement- flagella, slime • Metabolic diversity- heterotrophs and autotrophs (chemo- or photo-)

  6. Bacteria Energy Production • Respiration or fermentation (with or without O2) • Obligate aerobes: needs O2 to live • Obligate anaerobes: cannot live with O2 • Facultative anaerobes: can live with or without O2

  7. Bacteria Reproduction • Binary fission: (asexual) DNA is replicated and the organism splits in half • Conjugation:(sexual) genetic info is exchanged across a “bridge” • Spore formation: haploid cell that can withstand hard conditions and form a new organisms when the time is right

  8. Importance of Bacteria • Decomposers- break things down • Nitrogen fixation- cycles N thru atmosphere • Human uses: food, oil spills, medicine, intestines

  9. Treating Bacteria • Bacteria have homeostasis too! Change the conditions to stop growth • Temp, salt, pH, etc. • Sterilization (heat), disinfection (chemicals) • Antibiotics- kill bacteria or stop reproduction

  10. 19-2 Viruses • Categorized by what they infect: • Plant, animal, bacteriophage • Capsid- protein coat- signifies which host to infect (host must have a receptor) • NOT alive- has genetic material but can’t repro on own • Ex: flu virus, HIV

  11. Virus Replication • Lytic: enters host cell, copies itself continuously and bursts (lyses) • Lysogenic: combines/replicates viral DNA with host DNA • Prophage: viral DNA embedded within host DNA

  12. Treating Viruses • Antibiotics WILL NOT work! • Prevention is key! • Vaccination: inject a weak form of a virus in order to get the antibodies (immunity)

  13. The Body’s Defense System • homeostasis=includes regulating microbes • Lines of defense: • 1. physical barriers- block entry (skin) • 2. inflammation- increased blood flow • 3. immune system

  14. Immune System • Recognizes the “bad guys” • Every bacteria/virus has antigens (proteins) • Immune system makes antibodies • Antibodies fight the antigens • Vaccines- shows antigens ahead of time- allows body to create antibodies (immunity)

  15. White Blood Cells (WBCs) • Immune system MVP • 2 types: • 1. B cells: make antibodies • Memory B cells • 2. T cells: • Killer T cells: kill infected cells • Helper T cells*: help all other WBCs

  16. When the immune system goes wrong… • Allergic reactions- increase in system- produces histamines • Autoimmune diseases- system attacks self • Immunodeficiency- decrease in system- helper T cells destroyed (ex: AIDS) • inflammation- older people

  17. Other Pathogens • Protozoa- unicellular parasites • Algae/Dinoflagellates- produce toxins • ex: red tide • Fungi- athletes foot, ringworm • Parasitic Worms- tapeworm

  18. Viroids and Prions • Viroids: single stranded RNA molecules enter infected cells • Prions: tiny protein particles enter the brain and affect the nervous system- no DNA/RNA • Ex: mad cow disease

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