What is a flagellate?
A flagellated form
- Flagella are usually anterior
- Usually 2+ flagella
What are the flagellate sub-groups?
Diplomonadida, Euglenozoa
What are Diplomonadida? Give an example of a diplomonadid
Diplomonadids lack mitochondria but do possess mitosomes (don’t generate ATP)
- Most are anaerobic
- Many are parasites
Giardia is an intestinal parasite that causes diarrhoea
- Lives in cyst AND trophozoite form
What are Euglenozoa? Give an example of a euglenozoids
Many free living and some parasitic species of flagellates
- Kinetoplastids are parasitic euglenozoids
What is a kinetoplastid? Give an example
Parastic euglenozoids that are heterotrophic and move by flagella.
- Named because mitochondria has large circular DNA
- Divide by binary fission
Trypanosomes are kinetoplastids
What phyla belong to the alveolata group?
The apicomplexans and ciliates
What are apicomplexans?
Phylum Apicomplexa. Obligatory parasites (mostly intracellular) named for a special apical complex congregating at both poles used for cell invasion
- They move by gliding motility using apical complex
How do apicomplexans use their apical complex to move?
The apical complex secretes organelles and molecules from anterior end which flow along the body to create movement
What phylum does the parasite Babesia belong to? Describe its life cycle
Babesia is an apicomplexan transmitted by cattle ticks that invades the red blood cells of the host (cattle)
Life cycle:
1. Parasite enters red blood cell
2. Ring stage + amoeboid form (trophozoites)
3. Binary fission
4. Pyriform bodies (merozoites)
5. Cruciform bodies
6. Ingestion of infected blood cells by tick
7. Infected eggs laid by tick
What are ciliates? Give an example of a ciliate
Phylum Ciliata. Freshwater unicellular alveolates that use cilia for movement + feeding
- Filter feeding
They have a unique dual nucleus and undergo conjugation and cell division
Ex. = Balantidium coli in pigs
What is conjugation, and how often does it occur?
A form of sexual reproduction where the macronucleus is broken down and remade from copied micronuclei.
Occurs once every ~100-200 generations, when macronucleus degrades
1. Macro degrades, micro undergoes meiotic division (4 at end)
2. 3 of 4 haploid micros degrade
3. Remaining micro divides one more time
4. Copied micro is swapped with partner
5. Original haploid micro fuses with copy from partner
6. New macro is formed, cells separate
What are the groups of algae?
Rodophyta/red algae: some multicellular, use chlorophyll and another pigment for photosynthesis
Chlorophyta/green algae: can be unicellular, colonial, multicellular. closest relatives to land plants
What are amoebae?
Cells that move by cytoplasmic flow through projections called pseudopodia
- Flagellum usually absent
- Heterotrophs
- Pseudopodia also used to capture prey
Describe opportunistic parasitic amoebae.
Free living amoebae that can enter the brain/eye of host, usually through freshwater contact
What are entamoeba?
Obligate parasites that cause amoebic dysentery in humans and live in the intestines.
- Also found in dogs but don’t usually cause disease
What are slime moulds?
Originally thought to be fungi, but some are true amoebae
Describe the Opisthokonta group.
Named for presence of single posterior flagellum in cell. The group including animals - think of spermatozoon
What are the closest relatives to animals?
Choanoflagellates. Their flagella produce a water current for feeding
