6. Parasitic Protists Flashcards
What lineage do the giarda lamblia belong to?
Diplomonad
What is the mode of transmission for giarda lambia?
- Transmitted by cysts in food and water
- Adheres to intestinal epithelium to absorb nutrients from the host
What is the treatment for Giardia lamblia?
Treatment with 5- nitroimidazole drugs
What does the trophoziote structure have?
The trophozoite has two nuclei and associated sets of paired flagella
- Originally thought to have no mitochondria, but they have mitochondrial remnants (mitosomes) to make iron-sulfur proteins
What do parabasalids cause?
Trichomonas vaginalis causes venereal disease, usually not severe
What respiration method does the parabasalid use?
- Anaerobic
- Converts glucose to pyruvate by glycolysis
- Converts pyruvate to acetate in an organelle known as hydrogensome
What is the hydrogenosome?
- Derived from mitochondria
- Independent evolution in Trichomonas and other microbes, some still with DNA
- Under anaerobic conditions produces H2
What is the main treatment of parabasalids?
5-nitroimidazoles
Where does the name kinetoplastid come from?
Kinetoplastids are so named for their clump of DNA at the anterior end of the mitochondria (kinetoplast)
What is the variable region on the kinetoplastid known as?
- Variable surface glycoproteins coat
- VSG coat constantly changing types of glycoproteins to evade the host immune system recognition
What diseases are caused by kinetoplastids?
They swim in the blood stream and cause Chagas’ disease, African sleeping sickness, leishmaniasis
What is the method for combatting kinetoplastids?
- Very few effective drugs and bad side effects
- Target the insect vectors
What is the insect vector for sleeping sickness
tsetse fly
What is the vector of Chagas’ disease?
The assassin bug
What is the purpose of the cilia in ciliates?
They are covered in cilia for motility and capturing food (movement in water funnels in food)
What is the mating type of ciliate genetics determined by?
Mating type is determined by maternal cytoplasm that contains small RNAs
What is the process of sexual reproduction in paramecium?
- Two different mating types form a cytoplasmic bridge
- Meiosis produces four haploid micronuclei, three of which disintegrate
- Each remaining micronucleus divides by mitosis
- The conjugate pair swaps micronuclei
- The haploid micronuclei fuse, forming a diploid micronucleus
- The micronucleus undergoes three rounds of mitosis producing 8 micronuclei
- The original macronucleus disintegrates and four of the micronuclei become macronuclei
- Two rounds of cell division produces four daughter cells.
What is the name of the parasite in the amoeba lineage?
Entamoeba histolytica
- Cause the disease amebiasis
What does an entamoeba histolytica infection cause?
Dystentery (colitis), spread blood, and eventual liver abscess
What is the mode of transmission of entamoeba histolytica?
- Either ingests or lyses red blood cells
- Transmission by faecal contamination of food or water
What is the role of cysts in entamoeba histolytica?
- Cysts last several months
- Cysts form trophozoites in intestine after ingestion
What is the entamoeba histolytica treated with?
5-nitroimidazole
What parasites come from the phylum apicomplexa and what do they have in common?
All intracellular parasites
- Toxoplasma Gondii
- Plasmodium
- Cryptosporidium
Do organisms for the phylum apicomplexa photosynthesise?
- They are from a photosynthetic ancestor
- Do not photosynthesise anymore but they contain a remnant chloroplast for synthesis of fatty acids
What is the apical complex used for?
The apical complex is used to burst out of a used host cell and to invade using the apical complex
Who is the main target for toxoplasma gondii?
- Usually not severe in humans
- Fatal in immunocompromised individuals
- Developmental defects in infected foetus as the microbe can cross the placenta
What is a definitive host?
Where the sexual cycle occurs
What is the definitive host of the toxoplasma gondii?
Infects most mammals but the cat is the definitive host
What are some common risks of exposure for toxoplasma gondii?
Common risk of exposure is kitty litter or uncooked infected meat
What was the microbe causing the Irish famine?
Phytophthora infestans
What are the target cells for plasmodium?
Infects red blood cells and liver cells
What disease does the plasmodium cause?
Malaria
What is the relationship between the plasmodium and the host?
Each plasmodium species infects only one small host
What is the vector of the plasmodium?
Mosquito
What are the 3 cycles involved in plasmodium infection?
A. Exoerythrocytic cycle
B. Erythrocytic cycle
C. Sporogonic cycle
What was the first drug against malaria?
Quinine
