Biology 625
Fall semester lecture note outline

Updated: 24 September 1999

The text below simply represents a crude lecture outline of one of the topics covered in class. It is not meant to substitute for attending lectures or ignoring the textbook. Additional material, including line drawings, kodachromes, and more extensive information on life-cycles and basic biology, will be supplied in the lectures.

TOPIC # 25: Basic biology and systematics of parasitic Protozoa

  1. Basic considerations
    1. unicellular eukaryotes
    2. possess organelles that often function similarly to organs and systems of multicellular organisms
    3. parasitic forms with holozoic nutrition
    4. basic forms of locomotion
      1. flagella
      2. cilia
      3. pseudopodia
      4. gliding
    5. reproduction n strategies
      1. asexual
        1. longitudinal binary fission (equal division of organism into 2 across longitudinal axis)
        2. transverse binary fission (equal division of a ciliate into 2 across transverse axis)
        3. budding (fragmentation into 2 or more unequal fragments)
        4. multiple fission (merogony; schizogony; multiple karyokinesis followed by multiple cytokinesis)
        5. endodyogeny (2 daughter cells arising from internal budding of parent; many parental membranes and organelles utilized)
        6. endopolyogeny (more than 2 daughter cells resulting from internal budding of parent)
      2. sexual
        1. conjugation (in ciliates, pairing and temporary plasma membrane fusion for genetic exchange)
        2. syngamy (fusion of gametes)
        3. anisogamy (dissimilar gametes)
        4. isogamy (similar gametes)
  2. Basic systematics
    1. the systematics of the protozoa are in continual flux. They've done away with the old phylum "Protozoa," so the term tends to be retained only as a common name for the group. The International Code of Zoological Nomenclature applies to most protozoa; and, within that code, there are rules for naming lower taxa. However, there are basically no rules for higher taxa (i.e. kingdoms, phyla, classes, etc.) so various researchers tend to "create" new names thinking their names will catch on over those created by others. For instance, instead of utilizing the term "Kingdom Protozoa," they now tend to call it the "Kingdom Protista." Some even call it the "Kingdom Protoctista," although I've always felt the name implies a rubber glove needs to be used to work with the taxon. Recent molecular evidence suggests three very ancient lineages exist within the protozoa, and some have suggested the protozoa be split into three different Kingdoms.
    2. The scheme used in class is a simplified and rather traditional version, and the highest taxa employed will be limited to phyla. That should eliminate some phylogenetic problems. In some cases, however, this traditional scheme may not reflect all evolutionary relationships as proposed by biochemists and molecular biologists.
      1. "Sarcomastigophoras" (flagellates and amoeba)
        1. The Mastigophora (flagellates; newer classification schemes suggest four separate phyla may be involved. For simplicity in this class, however, they will all be lumped together as "flagellates")
        2. The Sarcodina (amoebae; this group is usually considered a phylum or subphylum, depending upon the author. Some members reveal distinct flagellate affinities)
      2. Superphylum: Alveolata (I've never really liked this name. It almost sounds like these protozoa have lungs or something). This taxon seems to show several groups or phyla as being related evolutionarily. These include the dinoflagellates, apicomplexans, ciliates, and acetosporans (1993, Microb Rev 57: 954-994; 1995, Mol Biol Evol 12: 573-581). Three of the groups have parasitic members important to this class:
        1. Phylum: Apicomplexa
        2. Phylum: Ciliophora (some people have split these into a whole bunch of different phyla)
        3. Ascetosporans (haplosporidia and paramyzea, now placed in two separate phyla (1996, J Parasitol 82: 616-623); you will not be tested over these taxa although I'll try to talk about basic aspects, time permitting)
      3. The Phylum Microspora

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