Week 3 - Protozoa

• Protozoa are 'chimeras'. What does this mean?


  • They are derived from at least two genetically different cell types
  • They have a mixture of characteristics
• What kind of cells are protozoa? (Eukaryotes or prokaryotes)


  Eukaryotes
• How were the nuclear envelope and membranes of some other eukaryotic organelles created?


  By the infolding of parts of the plasma membrane
• How did mitochondria and chloroplasts evolve? What is the name given to this process?


  Mitochondria and chloroplasts are the result of prokaryotes engulfing smaller prokaryotes. The engulfed prokaryotes developed a symbiotic relationship with the cell that engulfed them.

  • This process is called 'endosymbiosis'
• What is the name of an intracellular parasite (bacteria species) whose internal stucture is very similar to mitochondria?


  Rickettsia spp.
• How are chimeras created?


  Through grafting / transplantation of tissues
• What genus contains protozoa species that have chloroplasts and flagella?


  Euglena
• What are 5 features that can characterise groups of protozoa?


  • Mode of movement
  • Mode of nutrition
  • Habitat
  • Mode of reproduction
  • Possession of distinct organelles
• In ciliates, cilia are linked by tubules that form a...

  Kinetosome
• In ciliates, kinetosomes are arranged in rows that are called...


  Kineties
• Ciliates have an oral groove. What is the function of this?


  Allows the uptake of food particles + nutrients (feeding)
• How do cilia facilitate the uptake of food particles and nutrients?


  They move and direct the particles towards the oral groove
• What is an example of a ciliate species?


  Tetrahymena sp.
• What do the contractile vacuole and radiating canals allow? (Ciliates)


  Control of water regulation
• Some ciliates contain a macronucleus and micronuclei. Does the number of macronuclei and micronuclei vary between ciliate species?


  Yes
• What is the only ciliate that can cause disease in humans?


  Balantidium coli
• How do suctorian ciliates feed?


  They remove the cytoplasm from other cells using extrusomes
• Approximately how many species does the flagellates group contain?


  1000
• Many flagellates have ....


  Chloroplasts
• What environment are flagellates usually found in?


  Freshwater
• What are the two ways in which flagellates store food?


  • As fat
  • As paramylon
• What is paramylon and when can it be used? (flagellates)

  A starch-like carbohydrate. Can be used as a food source in adverse conditions
• Flagellates contain an 'eye-spot'. What is this made of and why is it important?


  The eye-spot is made of light sensitive tissue. It allows protozoa to move towards brighter sunlight, making photosynthesis more effective.
• What environments are flagellates often found in?


  Aquatic
• True or false ? : Flagellates can be either saprotrophic or phagotrophic 


  True
• What are 2 examples of flagellate species?


  • Heteronema sp.
  • Anisonema sp.
• Some protozoa have pellicles. What are these and what are their functions?


  Pellicles are thin outer membranes. They allow cells to retain their shapes
• How are eukaryotic flagella attached to the cells? What about in prokaryotes?


  Eukaryotes = attached by rootlets

  Prokaryotes = ring structures are embedded into the cell
• What are bacterial flagella composed of?


  Flagellin
• What are eukaryotic flagella composed of?


  Tubulin
• Are bacterial flagella single-stranded or multi-stranded?


  Single-stranded
• Are eukaryotic flagella single-stranded or multi-stranded?


  Multi-stranded
• Is a plasma membrane present in bacteria flagella?


  No
• What protozoa species have many nuclei but no mitochondria?


  Entamoeba spp.
• What are characteristic features of giardia species?


  • 2 nuclei
  • No myosin
  • No peroxisomes
  • No mitochondria
• Giardia are 'diplomonads'. What does this mean?


  They have 2 nuclei
• What structure allows giardia to attach to the gut lining?


  An adhesive ventral disc
• What is a hypothesis for the origin of amitochondrial protists?


  They diverged from the eukarya lineage before the endosymbiotic origin of mitochondria
• How do giardia spp. produce energy without mitochondria?


  They contain residual bacterial genes which encode enzymes for fermentative metabolism. This allows them to respire via fermentative metabolism
• Can apicomplexa infect both invertebrates and vertebrates?


  Yes