Introduction into Protists Flashcards
Reasons to study protists?
- Understand diversity of life
- Food chain
- Photosynthesis
- Mutualistic symbiosis with other organisms
- Understanding stress responses
- Models of multicellularity
- Predators and Prey
- Agents of disease
Do protist make up little or much of the eukaryotic tree of life?
Very much of tree of life
Who discovered protists?
Leeuwenhoek
Define protists:
- Group based on general similarities but exhibit a wide range of morphologies, inhabit many different habitats
- Unrelated to plants, animal and fungi
- Widespread
What do protists have in common with one another?
- Require a water-based environment (fresh/marine/snow/damp soil/animal gut)
- Undergo mitosis
- Require presence of oxygen
- Unicellular
- Motile
How do protists differ?
- How they obtain nutrition
- How they move
What are different ways in which protists can obtain nutrients?
- Phagocytosis
- Photosynthesis
- Absorption of nutrients
- Symbiosis
What are different ways in which protists move?
- Pseudopodia
- Cilia
- Flagella
Are zooxanthellae autotrophs or heterotrophs?
autotrophs
Are Euglena autotrophs or heterotrophs?
Heterotrophs
What are zooxanthellae?
Symbiotic dinoflagellate protists that live within hard or stony corals
What does it mean for zooxanthellae to be autotrophs?
Produce all nutritional substances required for them to live
How much do zooxanthellae provide of coral energy via photosynthesis?
80%
What do zooxanthellae take up?
Nutrients released by corals metabolism such as Nitrogen and Carbons Dioxide
What is Euglena?
- Single, motile, flagellum for movement
- Sense light using red “eye spot”
- Contain chloroplast
What do Euglena feed on in the dark?
Other protists
What shows extensive evidence of protists preying on other protists?
Fossil record
What may have played a critical role in the diversification of eukaryotes?
Predation
Why are protists considered all eukaryotes?
- Cells have nucleus and other membrane-bound organelles
- Most single-celled
What was the last eukaryotic common ancestor?
Flagellated protist
What are many of intracellular organelles of protists?
Flagellate or ciliate
What are different morphologies of protists?
- Amoebae
- Flagellates
- Ciliates
- Cysts/Cocci
- Hyphae
- Diatoms
Why is it difficult to classify just on morphology?
Some protists have different morphological stages dependent on life cycle and enviroment
What has advances in DNA sequencing allowed?
Classification protists with greater preseason
What are dinoflagellates?
- Marine/photosynthesis/free-living or endosymbionts
- Two flagella (equatorial/longitudinal groove)
- Amoeboid form
- Primary producers of organic mater
What can dinoflagellate endosymbionts with?
Coral
What is dinoflagellate associated with?
Toxic red tides
What are loboseans?
- Naked or testate form
- Predators, parasites or scavengers
- Heterotrophic
- Phagocytes
- Free living
- Disease causing
What are heteroloboseans?
Amoeboid organisms
Disease causing
What disease does heterolobosean causes?
Brain eating amoeba
What are ciliates?
- Possesses hair-like cilia (allow complex behaviours)
- Complex cellular forms = contractile/digestive vacuoles
- Two types of nuclei
- Most heterotrophic
What are euglenoids?
- Flagellate with universal paracrystalline rod
- Mitochondria
- Cell shape determined by spiralling strips of protein
- Some photosynthetic with photoreceptors
What are kinetoplastids?
- Unicellular, flagellate with unique paracrystalline rod
- Mitochondrion = kinetoplast
- Medically important vector-borne pathogens
What are phaeophyta?
- Marine
- Multicellular filaments
- Sessile/planktonic form
- Giant kelps
- Important in industry (cosmetics/ice cream)
What are diplomonads?
- Unicellular, posses mitosomes
- Posses two nuclei of equal size
- Multiple flagella
- Disease causing
What disease does giardiasis?
Giardia lamblia
What are parabasilids?
- Parabasal body
- Hydrogenosomes (anaerobic)
- Genome lacks introns (2x size of human)
- Disease causing
What are diatoms?
- Unicellular (some associate with filaments)
- Carotenoids give golden or brown colour
- Only male gamete have flagella
- Two-piece silica cell walls
- Bilateral or radial symmetry
- Synthesis aquatic, phytoplankton
What are foramiferans?
- Plantonic or sessile
- External, spiral shells or calcium carbonate or chitin
- Branching pseudopods extend through shell apertures to form a sticky reticulate net
- Contributor to lime stone
What are radiolarians?
- Marine heterotrophs
- Tests made up of silica
- Thin, stiff pseudopods reinforced by microtubules
- Radial symmetry
- Largest unicells
What are myxomycetes?
- Cellular slime moulds
- Single celled haploid myxamoebae
- Nutrient starvation = myxamoebae swarm to make pseudoplasmodium (multicellular) or slugs (migrate)
- Produce stalk and sporangium
What are apicocomplexans?
- Contains an apical complex that facilitate host invasion
- All parasites
- May complex life-cycles and multiple hosts
What are many medically important pathogens?
Protists
