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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

Chapter 19

Bacteria and Viruses

remember homeostasis
Remember homeostasis?
  • Maintaining proper internal conditions
  • pH, temp., water/salt balance, O2, CO2, etc.
factors for disease
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)
19 1 bacteria
19-1 Bacteria
  • Prokaryotes
  • Monera
  • Can be beneficial or disease-causing
    • Good: intestinal bacteria
    • Bad: strep throat, pneumonia
  • Everywhere!
identified by
Identified by:
  • Shape- bacilli (rod), cocci (round), spirilla (spiral)
  • Cell walls- Gram +/- (peptidoglycan)
  • Movement- flagella, slime
  • Metabolic diversity- heterotrophs and autotrophs (chemo- or photo-)
bacteria e nergy production
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
bacteria reproduction
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
importance of bacteria
Importance of Bacteria
  • Decomposers- break things down
  • Nitrogen fixation- cycles N thru atmosphere
  • Human uses: food, oil spills, medicine, intestines
treating bacteria
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
19 2 viruses
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
virus replication
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
treating viruses
Treating Viruses
  • Antibiotics WILL NOT work!
  • Prevention is key!
  • Vaccination: inject a weak form of a virus in order to get the antibodies (immunity)
the body s defense system
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
immune system
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)
white blood cells wbcs
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
when the immune system goes wrong
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
other pathogens
Other Pathogens
  • Protozoa- unicellular parasites
  • Algae/Dinoflagellates- produce toxins
    • ex: red tide
  • Fungi- athletes foot, ringworm
  • Parasitic Worms- tapeworm
viroids and prions
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