Lecture 6 - Parasitic Protists

Question 1

Describe the characteristics of protists

Answer 1

• Unicellular
• Eukaryotic
• Not animals, plant, or fungi

Question 2

Mention the 6 major groups of parasitic protists. Give an example for each.

Answer 2

Diplomonads - Giardia
Parabasalid - Trichomonas vaginalis
Kinetoplastid - Leishmania & Trypanosoma
Ciliates - Balantidium & Paramecium
Amoebozoa - Entamoeba
Apicomplexan - Toxoplasma & Plasmodium

Question 3

Describe the parasite Giardia lamblia and the disease it caused.

Answer 3

Giardia lamblia is an example of a diplomonad. It is an agent of the “traveller’s diarrhoea”, which transmitted by cysts in food and water.

Question 4

Kinetoplastids are usually bloodstream parasites. Mention three examples of diseases caused by kinetoplastids.

Answer 4

Leishmaniasis - Leishmania
African Sleeping Sickness - T. brucei (Vector: Tsetse fly)
Chagas Disease - T. cruzi (vector: Triatomine bug)

Question 5

Explain how kinetoplastids avoid the immune system.

Answer 5

By changing their surface molecules constantly

Question 6

Balantidium coli causes the disease _______ through fecal transmission of cysts.

Answer 6

Balantidiasis

Question 7

Describe the mechanism of sexual reproduction in Paramecium.

Answer 7

• Two different mating types form a cytoplasmic bridge
• Each produces 4 haploid micro nuclei through meiosis, 3 disintegrate
• The remaining micronucleus divides by mitosis
• The pair swapped micronuclei
• The two haploid micronuclei fuse and undergo three rounds of mitosis, creating 8 micronuclei
• Original macronucleus disintegrate, while four of the micronuclei macronuclei
• Two rounds of cell division produce 4 daughter cells

Question 8

Apicomplexans are all ___________.

A. intracellular
B. extracellular

Answer 8

A. intracellular