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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. 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

  18. Chapter 20Protists

  19. 20-1 The Kingdom Protista • What is a protist? • Anything that is not a plant, animal, fungus or prokaryote • First eukaryotes • Most unicellular • Classified by how they obtain nutrients

  20. 20-2 AnimallikeProtists (Protozoans) • Heterotrophs • Categorized by how they move: • Flagella • pseudopodia: temporary projection of cytoplasm • food vacuole • cilium: short hair-like projections • parasitic- don’t move on own

  21. AnimallikeProtists and Disease • Malaria (mosquitoes) • Treatments/vaccines only partially effective • African sleeping sickness (tsetse fly) • Unconsciousness can be fatal

  22. 20-3 Plantlike Protists (Unicellular Algae) • Chlorophyll and accessory pigments • Ex: diatoms and dinoflagellates (glowing water!)

  23. 20-4 Plantlike Protists (Red, Brown and Green Algae) • Red algae- good at harvesting light E- can live at great depths • Brown algae- brown pigment • Green algae- VERY plantlike

  24. Human uses of algae • “grasses” of the sea- base of food chain • O2 production • Medicine- vitamin C and iron • Food- sushi wraps, ice cream/pudding thickener • Industry- plastics, agar

  25. 20-5 FunguslikeProtists • Recycle organic matter • Different cell walls than true fungi • Slime molds • Water molds- potato famine

  26. Ecology of Protists • Base of food chain (ex: phytoplankton) • Symbiotic relationships (ex: termites) • Blooms (ex: red tide) • Recycle organic matter (ex: slime molds)

  27. Chapter 21Fungi

  28. 21-1 What is a fungus? • Eukaryotic heterotrophs with cell walls (chitin) • Digest food externally then absorb it • Can be parasitic

  29. Fungi Structure • Hyphae: microfilaments that combine to form mycelium • Increase surface area to absorb food • Fruiting body: reproductive structure • “mushroom”

  30. Fungi Reproduction • Asexual: cells/hyphae break off • Sexual: mating types “+” and “-” • Spores: easily spread

  31. 21-2 Classification • Based on structure and reproduction • Common molds (bread mold) • Sac fungi (yeasts) • Club fungi • Imperfect fungi (unknown repro. cycle)

  32. 21-3 Fungi Ecology • Saprobes- obtain nutrients from decaying organisms • Decomposers- recycle nutrients back into earth

  33. Ecological Relationships • Parasites- affect crops (wheat rust) and humans (athletes foot, ringworm) • Symbionts (symbiosis) - work together with other organisms • Lichens- photosynthetic organisms + fungus • Mycorrhizae- roots + fungus

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