6. Parasitic Protists

Question 1

What lineage do the giarda lamblia belong to?

Answer 1

Diplomonad

Question 2

What is the mode of transmission for giarda lambia?

Answer 2

• Transmitted by cysts in food and water

- Adheres to intestinal epithelium to absorb nutrients from the host

Question 3

What is the treatment for Giardia lamblia?

Answer 3

Treatment with 5- nitroimidazole drugs

Question 4

What does the trophoziote structure have?

Answer 4

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

Question 5

What do parabasalids cause?

Answer 5

Trichomonas vaginalis causes venereal disease, usually not severe

Question 6

What respiration method does the parabasalid use?

Answer 6

• Anaerobic
• Converts glucose to pyruvate by glycolysis
• Converts pyruvate to acetate in an organelle known as hydrogensome

Question 7

What is the hydrogenosome?

Answer 7

• Derived from mitochondria
• Independent evolution in Trichomonas and other microbes, some still with DNA
• Under anaerobic conditions produces H2

Question 8

What is the main treatment of parabasalids?

Answer 8

5-nitroimidazoles

Question 9

Where does the name kinetoplastid come from?

Answer 9

Kinetoplastids are so named for their clump of DNA at the anterior end of the mitochondria (kinetoplast)

Question 10

What is the variable region on the kinetoplastid known as?

Answer 10

• Variable surface glycoproteins coat

- VSG coat constantly changing types of glycoproteins to evade the host immune system recognition

Question 11

What diseases are caused by kinetoplastids?

Answer 11

They swim in the blood stream and cause Chagas’ disease, African sleeping sickness, leishmaniasis

Question 12

What is the method for combatting kinetoplastids?

Answer 12

• Very few effective drugs and bad side effects

- Target the insect vectors

Question 13

What is the insect vector for sleeping sickness

Answer 13

tsetse fly

Question 14

What is the vector of Chagas’ disease?

Answer 14

The assassin bug

Question 15

What is the purpose of the cilia in ciliates?

Answer 15

They are covered in cilia for motility and capturing food (movement in water funnels in food)

Question 16

What is the mating type of ciliate genetics determined by?

Answer 16

Mating type is determined by maternal cytoplasm that contains small RNAs

Question 17

What is the process of sexual reproduction in paramecium?

Answer 17

1. Two different mating types form a cytoplasmic bridge
2. Meiosis produces four haploid micronuclei, three of which disintegrate
3. Each remaining micronucleus divides by mitosis
4. The conjugate pair swaps micronuclei
5. The haploid micronuclei fuse, forming a diploid micronucleus
6. The micronucleus undergoes three rounds of mitosis producing 8 micronuclei
7. The original macronucleus disintegrates and four of the micronuclei become macronuclei
8. Two rounds of cell division produces four daughter cells.

Question 18

What is the name of the parasite in the amoeba lineage?

Answer 18

Entamoeba histolytica

- Cause the disease amebiasis

Question 19

What does an entamoeba histolytica infection cause?

Answer 19

Dystentery (colitis), spread blood, and eventual liver abscess

Question 20

What is the mode of transmission of entamoeba histolytica?

Answer 20

• Either ingests or lyses red blood cells

- Transmission by faecal contamination of food or water

Question 21

What is the role of cysts in entamoeba histolytica?

Answer 21

• Cysts last several months

- Cysts form trophozoites in intestine after ingestion

Question 22

What is the entamoeba histolytica treated with?

Answer 22

5-nitroimidazole

Question 23

What parasites come from the phylum apicomplexa and what do they have in common?

Answer 23

All intracellular parasites

• Toxoplasma Gondii
• Plasmodium
• Cryptosporidium

Question 24

Do organisms for the phylum apicomplexa photosynthesise?

Answer 24

• They are from a photosynthetic ancestor

- Do not photosynthesise anymore but they contain a remnant chloroplast for synthesis of fatty acids

Question 25

What is the apical complex used for?

Answer 25

The apical complex is used to burst out of a used host cell and to invade using the apical complex

Question 26

Who is the main target for toxoplasma gondii?

Answer 26

• Usually not severe in humans
• Fatal in immunocompromised individuals
• Developmental defects in infected foetus as the microbe can cross the placenta

Question 27

What is a definitive host?

Answer 27

Where the sexual cycle occurs

Question 28

What is the definitive host of the toxoplasma gondii?

Answer 28

Infects most mammals but the cat is the definitive host

Question 29

What are some common risks of exposure for toxoplasma gondii?

Answer 29

Common risk of exposure is kitty litter or uncooked infected meat

Question 30

What was the microbe causing the Irish famine?

Answer 30

Phytophthora infestans

Question 31

What are the target cells for plasmodium?

Answer 31

Infects red blood cells and liver cells

Question 32

What disease does the plasmodium cause?

Answer 32

Malaria

Question 33

What is the relationship between the plasmodium and the host?

Answer 33

Each plasmodium species infects only one small host

Question 34

What is the vector of the plasmodium?

Answer 34

Mosquito

Question 35

What are the 3 cycles involved in plasmodium infection?

Answer 35

A. Exoerythrocytic cycle
B. Erythrocytic cycle
C. Sporogonic cycle

Question 36

What was the first drug against malaria?

Answer 36

Quinine