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42 Cards in this Set
- Front
- Back
Why are protozoa eukaryotic?
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Because you can identify a nucleus.
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Are protozoa always parasitic?
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No, some are free living, commensal, symbiont or parasitic.
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Do all protozoa move?
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Yes, some more than others though.
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How does a protozoa obtain its nutrients?
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Engulfing a food particel via pseudopodia, ingesting it through a cytosome or soluble materials may be absorbed through the cell membrane.
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Describe protozoal reproduction.
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Can be sexual (involving the exchange of genetic material) or asexual involving binary or multiple fission.
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What are the two common forms of multiple fission?
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Schizogony and Sporogony.
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Describe schizogony.
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The nucleus divides many times, and each nucleus eventually accumulates a cytoplasm to form a whole organism. The parent cell is the schizont, the process is known as schizogony and the products of this process are schizozoites.
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Describe sporogony.
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The process between an unsporulated and sporulated oocyst. It involves the division of the zygote into a number of organisms that are infective to the DH. These are sporozoites
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Phyllum Apicomplexa: intra or extracellular?
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Intracellular.
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Complex or simple lifecycle?
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Complex.
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What are the three phases of reproduction in the apicomplexa?
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Schizogony, Gametogony and Sporogony.
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Are lifecycles of this phyllum direct or indirect?
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Both.
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Which genus does the arbitrary group coccidia have?
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Eimeria and Isospora
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Where are these two genera often found?
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The alimentary tract
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Are they usually host specific?
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Very. Also quite site specific as well.
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A sporocyst contains what?
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Sporozoites.
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How does the DH become infected with Eimeria or Isospora?
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Ingestions of a sporulated oocyst. Unsporulated oocyst aren't infective.
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What contains the sporocysts?
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The sporulated oocyst has a cyst wall around it.
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Outline the layers in in a sporulated oocyst.
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Cyst wall-sporocyst-sporozoite
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How many sporocysts does Eimeria have?
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4 each of which contains 2 sporozoites.
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How many sporocysts does Isospira have?
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2 each of which contains 4 sporozoites.
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What is the micropyle?
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The thin walled bit that allows escape of the sporozoites from the sporocyst.
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What factors are responsible for the excystment of the sporozoites?
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Dissolved carbon dioxide, bile salts and trypsin.
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Where does excystment usually occur?
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In the small intestine, and the sporozoites invade mucosal cells. Depth of penetration is dependent on species.
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What occurs once the sporozoites get into the mucosal cells?
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SCHIZOGONY. Results in the generation of several hundreds of schizozoites
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What contains the schizozoites?
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The schizont.
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How many cycles of schizogony are there?
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Usually two, although 3 sometimes occur.
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What happens to the schizozoites once developed?
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The cell they have infected bursts and the schizozoites can go on to infect neighbouring cells.
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What happens to the final generation of schizozoites?
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The invade cells to become macro or microgametocytes. Fertilisation occurs to produce a zygote which begins to produce the oocyst wall.
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What does the oocyst contain?
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The sporont.
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What is special about a progametocyte?
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Results in polyp formation. The progametocyte induces mitosis at the same time as it undergoes binary fission. Eventually the progametocyte becomes the progametocyte.
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What stage is passed in the faeces?
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Oocyst.
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Under optimum conditions, how fast can sporogony occur?
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24-48 hours.
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What is unique about some of the Eimeria and Isospira spp infecting carnivores?
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Sometimes can have paratenic hosts.
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Where are cryptosporidium located?
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In the brush border of epithelial tissue.
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Does crypto have sporocysts?
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NO
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How many sporozoites does crypto have?
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4
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Is autoinfection possible with crypto? Why?
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Yes, the fertilized oocyst sporulates immediately.
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What is the common stain used to detect crypto?
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Ziehl-Nielsen
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What are the two most important factors in determining the pathogenicity of a coccidia spp.?
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The rate of mulitplication and the site of the multiplication stages.
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What coccidial genus occurs in the gut of birds and ruminants?
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Eimeria
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What coccidial genus occurs in the gut of dogs and cats?
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Isospira
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