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42 Cards in this Set

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