Intro to Proto

• Protozoa


  Single-celled organism, generally microscopic, eukaryote

  
• Structures of protozoa


  • Cell membrane
  • Cytoplasm (endoplasm and ectoplasm)
  • Nucleus
  • Organelles
  • Locomotory apparatus (cilia, pseudopods, flagella)
  • Machinery for intake and excretion
• Pellicle


  Thin layer supporting the cell membrane that provides protection, flexibility, elasticity, and sometimes rigidity
• Contractile vacuoles


  Osmoregulatory organelles that imbibe fluid from the environment, and transport waste products from inside the cell to the outside
• Food vacuoles


  Stores food for digestion, analogous to stomach
• Glycocalyx


  Structure that allows protozoa to adhere to the surface of other cells

  
• Protozoa have mitochondria, Golgi apparatus, and endoplasmic reticulum

  
• Chromatoidal bodies


  Aggregate of RNA in the cytoplasm found in cyst stage, good diagnostic characteristic for differentiating cysts and trophozoites
• Trophozoites do not have chromatoidal bodies
• Trophozoite


  Active and growing stage that absorbs nutrients from the host, or may be free-living, oval to irregular-shaped, motile, disease-causing stage, dividing stage, feeding stage, formed by excystation, isolated from watery stool
• Cyst


  Inactive stage that helps to survive in unfavorable environmental conditions, and resist desiccation, spherical-shaped, covered with thick, and tough cyst wall, with chromatoidal bar, infective stage, non-motile, non-feeding, formed by encystation, isolated from formed stool
• Trophozoites generally have one nucleus, but in cystic forms, about 1 - 4, except for Entamoeba coli which can have 1 - 8, while other references can reach up to 16

  
• Upon excystation of quadrinucleated cyst, there will be 4 trophozoites released
• Asexual Reproduction


  1. Simple binary fission

  2. Multiple fission (schizogony)

  
• Sexual Reproduction


  Sexually differentiated male and female gametes unite and form a zygote
• 4 Phyla of Human Parasitic Protozoa


  • Sarcodina
  • Mastigophora
  • Ciliophora
  • Apicomplexa

  
• Sarcodina


  • Move by extending pseudopods which are temporary or semipermanent extension of cytoplasm
• Mastigophora


  • Move by beating one or more flagella which are whip-like structures arising from the ectoplasm
• Ciliophora


  • Move by beating many cilia which are hair-like projections from the ectoplasm
• Apicomplexa


  • Non-motile, may have slight amoeboid movement with apical complex for penetration and invasion of target cells
• Pathogenic Sarcodina


  • Entamoeba histolytica
• Commensal Sarcodina


  • Entamoeba dispar
  • Entamoeba moshkovskii
  • Entamoeba hartmanni
  • Entamoeba coli
  • Entamoeba polecki
  • Entamoeba chattoni
  • Entamoeba gingivalis
  • Endolimax nana
  • Iodamoeba butschlii
• Entamoeba histolytica, Entamoeba moshkovskii, and Entamoeba dispar cannot be differentiated from each other UNLESS there is an ingested RBC in the trophozoite
• Entamoeba polecki and Entamoeba chattoni can be differentiated through isoenzyme analysis
• Entamoeba gingivalis is the only sarcodina that does not have a cystic stage
• Entamoeba


  Vesicular nucleus, varying numbers of chromatin granules to nuclear membrane, karyosome: centrally or near centrally located
• Iodamoeba butschlii has characteristic glycogen vacuole that is demonstrated with iodine