Protista 1

Question 1

Entamoebae (a)

Answer 1

• Anaerobic human parasite.
• Entamoeba histolytica causes amoebic dyssentery. (small details in lecture 8)
• Non-pathogenic amoebae (Sarcodina) also exist within the Protista.

Question 2

Entamoebae (b)

Answer 2

• Phagocytotic heterotrophs in water and soil.

- Also use CYST formation during unfavourable environmental conditions

Question 3

Ciliates- Paramecium (a)

Answer 3

• Phylum Ciliophora
• Relatively complex eukaryotic microbes
  - Cilia for motility
  - Phagocytotic
  - Some discharge barbed trichocysts for capturing prey and defence (also toxicycsts that release poison)

Question 4

Ciliates- Paramecium (b)

Answer 4

• Usually have 2 nuclei
  - One for reproduction (single copy of genome)
  - One for metabolism ( multiple copies of genome)
• Cilia create a spiral motion
• Paramecium food ingestion and excretion
• Paramecium also has a contractile vacuole for osmotic balance
  - It is hypotonic to its fresh water surroundings

Question 5

Ciliates- Plasmodium

Answer 5

• Phylum Apicomplexa
  - Malaria and toxoplasmosis parasites are in this phylum
  - Toxoplasmosis is a cat-human transmission that affects 7-70% of people depending on the area

-Plasmodium vivax is the cause of malaria (small details in L8)

Question 6

The eukaryotic cell is

Answer 6

• Larger than a prokaryotic cell
• Has membrane-bound organelles
• Greater internal complexity
• specialized method of cell division that involves meiosis (genetic recombination)

Question 7

Protista

Answer 7

eukaryotic, unicellular and multicellular

They are ‘polyphyletic’

Question 8

The fungi are descended from fungi-like single celled heterotrophic eukaryotes called……

Answer 8

Chytrids

Question 9

Animals are descended from single celled heterotrophic eukaryotes called…..

Answer 9

Choanoflagellates

Question 10

The plants are descended from single celled photosynthetic eukaryotes called…….

Answer 10

chlorophytes

Question 11

Diplomonads

Answer 11

• The diplomonads are obigate human pathogens
  - lack mitochondria
  - Giardia causes giardiasis, a common infection from poor restaurant hygiene ( i.e: Giardia Lamblia)

Question 12

Microsporidia

Answer 12

• They are mainly animal parasites
• Lack mitochondria and flagella
• They have chitin cell walls like fungi
• Sequencing of other genes now places them within the fungi
  - They are now regarded as highly reduced fungi

Question 13

Trichomonads (a)

Answer 13

These are anaerobic, mitochondria and flagella posessing microbes that occur as animal endoparasites or endosymbionts

Question 14

Trichomonads (b)

Answer 14

• Trichomonas vaginalis causes trichomoniasis

- This is the most common eukaryotic pathogen in developed countries

Question 15

Trypanosomes - Phylum Euglenozoa

Answer 15

• Single flagellum
  - but change morphology according to the host
• All are obligate parasites
  - important in human health, cause sleeping sickness (trypanosomiasis)
  - Some species have secondary animal or plant hosts.
  E.g: Trypanosoma cruzi

Question 16

Euglenoids- Phylum Euglenozoa

Answer 16

• Mainly live in nutrient-rich freshwater
  - Two flagella
  - Plus a photoreceptive eyespot and several chloroplasts
  - Also a contractile vacuole that acts to expel excess water and maintain osmotic balance within the cell.
  - Can live as autotrophs or heterotrophs

Question 17

Recap

Answer 17

1. Diplomonads - Giardiasis
2. Microsporidia - Animal parasites
3. Trichomonads - Vaginal Infection
4. Trypanosomes- sleeping sickness
5. Euglenoids- fresh water
6. Entamoeba- dyssentery
7. Ciliate- Paramecium; plasmodium (malaria)