Biology Chapter 31: Fungi

Chapter 31: Fungi

• Fungi definition:

  • Systemic: infection that spreads throughout the body
  • Saprophytic: organism that feeds on decaying organic matter
  • Septate hyphae: hyphae with cross walls
  • Mycelium: main body of the fungus
  • Coenocytic: hyphae that are multinucleate
  • Pseudohyphae: chains of yeast cells that don't separate
  • Sporangiospores: asexual spores produced inside a sac
  • Dimorphic fungus: mold or yeast form depending on environment

• Contrast fungi with other eukaryotes and bacteria:

  • Bacteria only: prokaryotic, peptidoglycan cell wall, unicellular
  • Fungi only: eukaryotic, chitin cell wall, unicellular or multicellular, decomposers
  • Both: can reproduce asexually, can be pathogenic, some produce antibiotics

• Identifying common fungal specimens:

  • Look in the lab book, pages 322-324 for details.

• Medically important fungi and diseases/products:

  • Candida: cutaneous, oral, vulvovaginal candidiasis
  • Rhizopus: opportunistic mucormycosis
  • Penicillium: opportunistic infections (rare)
  • Trichophyton: dermatophytosis (ringworm, athlete's foot, nail infections)
  • Penicillium: produces penicillin

• Mechanism of action and applications of antifungal medications:

  • Miconazole: used to treat dermatophyte infections, candidiasis and topical fungal infections; available over-the-counter.

Chapter 32: Arthropods

• Arthropod terminology and structures:

  • Molting: periodic shedding and regrowth of exoskeleton
  • Invertebrate: animals lacking a backbone
  • Vector: organism transmitting disease
  • Chitin: found in cell walls of fungi and exoskeletons of arthropods
  • Ectoparasite: lives on the outside of a host

• Contrast arthropods with other eukaryotes and bacteria:

  • Role in environment: pollinators, decomposers, predators, disease vectors
  • Characteristics: segmented bodies, jointed appendages, chitinous exoskeletons
  • Reproduction: sexual (mating), some parthenogenesis (asexual reproduction)
    • Other eukaryotes: sexual and asexual reproduction, spore formation, some protists
    • Bacteria: asexual (binary fission)

• Clinical importance of arthropods:

  • Vectors: transmit pathogens
  • Ectoparasites: transmit pathogens during feeding
  • Other diseases: scabies, pediculosis, burrowing into skin

Chapter 33: Protozoa

• Protozoa terminology and structures:

  • Pseudopodia: lobe-like cytoplasmic extensions for movement and feeding
  • Mixotrophic: capable of both heterotrophy and autotrophy (photosynthesis)
  • Schizogony: asexual reproduction producing multiple daughter cells at once
  • Cyst stage: dormant, protective stage
  • Trophozoite stage: actively feeding, reproducing stage
  • Mitosome/Hydrogenosome/Axostyle/Undulating membrane: mitochondrial remnants and other structural components

• Contrast protozoa with other eukaryotes and bacteria: - Single-celled; have nucleus, flagella, cilia, or pseudopods for movement - Predators, recyclers, and parasites - Can reproduce sexually (like animals, plants) and asexually (like fungi, algae)

• Identifying common protozoal specimens:

  • Look in lab book, pages 343-347 for details.

• Medically important protozoa and diseases:

  • Entamoeba histolytica: amoebiasis (gastroenteritis)
  • Giardia intestinalis: giardiasis
  • Leishmania species: leishmaniasis (cutaneous/visceral)
  • Plasmodium: malaria
  • Trichomonas vaginalis: trichomoniasis
  • Trypanosoma brucei/T. cruzi: African sleeping sickness/Chagas' disease

• Mechanism of action and applications of antiprotozoal medications:

  • Metronidazole: damages DNA of anaerobically respiring protozoa
  • Aminoquinolines: prevent parasite replication
  • Pentamidine: interferes with DNA, RNA, and protein synthesis

Chapter 34: Helminths

• Helminth terminology and structures:

  • Scolex: anterior end of tapeworm with suckers/hooks
  • Proglottids: segments of tapeworm with reproductive organs
  • Miracidium/Cercariae: larval stages of flukes
  • Nematode: roundworm
  • Dioecious (separate sexes) / Monoecious (both sexes)

• Contrast helminths with other eukaryotes and bacteria:

  • Role in environment: parasitic, harming hosts, influencing populations
  • Characteristics: multicellular, macroscopic, specialized structures for parasitism
  • Reproduction: sexual (dioecious or monoecious) or asexual stages, complex life cycles
    • Other eukaryotes: can be unicellular or multicellular, includes plants and fungi; sexual and asexual reproduction; complex life cycles
    • Bacteria: primarily asexual (binary fission)

• Identifying common helminthic specimens: (details in the lab book)

• Medically important helminths and diseases:

  • Liver fluke (Fasciola hepatica): Fascioliasis
  • Blood fluke (Schistosoma): Schistosomiasis
  • Tapeworm (Taenia): Taeniasis, Cysticercosis
  • Nematode (Enterobius vermicularis): Enterobiasis
  • Nematode (Ancylostoma duodenale): Ancylostomiasis
  • Nematode (Ascaris lumbricoides): Ascariasis

• Mechanism of action and applications of anthelminthic medications:

  • Praziquantel: alters cell membrane permeability
  • Albendazole/Mebendazole: inhibits microtubule formation affecting glucose uptake