Lecture 20 - Fungi (part 2) & Protists Flashcards
How are fungi key decomposers within the environment?
- they’re saprotrophs
• Break down wood, leaf litter, organic matter is soil
• Really any carbon-containing substrate -> even jet fuel!
• Provides inorganic nutrients essential for plant growth
Saprotrophs
ex: fungi
- sporotrophic fungi that get their nutrition from dead plant material & other non-living organic material
Endophytic
- fungi that associates with plants
- a fungus that lives inside a leaf or other plant part without causing harm to the plant
- a reason fungi can be mutualists
Symbiotic
- an ecological relationship b/t organisms of 2 different species that live together in direct & intimate contact
- we see this in LICHENS
- Symbiotic relationships between an ascomycete (or sometimes a basidiomycete or glomeromycete) fungus and a green alga and/or cyanobacterium
soredia
- in lichens, a small cluster of fungal hyphae with embedded algae
- how fungi reproduces asexually
Mixotrophs
• Mixotrophs, both photosynthetic and heterotrophic
• Have arisen independently in protist lineages
- we see this in protists
plastid
- organelle that does cool things, either photosynthesis or cellular respiration etc. within the cell
- are found in cells of photosynthetic eukaryotes
- we see this in secondary endosymbiosis (photosynthetic eukaryote becomes the new plastid)
nucleomorphs
Residual nuclei (nucleomorphs) are strongest evidence of EST b/c some organisms usually in Rhizaria & the cryptonomads retain these multiple nuclei even though they have their own nucleus themselves • Rhizaria and cryptonomads
pseudopodia
- a cellular extension of amoeboid cells used in moving & feeding
- we see this in the supergroup rhizarians
Phytoplankton
small planktonic things that photosynthesize
• Main cause of shellfish poisoning due to the toxins they produce
• Can result in huge “blooms”
- we see this in the diatoms (in the subgroup Stramenopiles)
accessory pigment
another pigment other than the main photosynthetic pigment
- usually help in either antioxidant properties or allowing the absorption of additional wavelengths of light
- so it’s an accessory pigment, it’s not the primary pigment
- we see this Brown Algae (in the subgroup Stramenopiles)
Holdfasts
anchorage
- a specialized structure in brown algae
Stipe
“stem”
- a specialized structure in brown algae
Blades
“leaves”
- a specialized structure in brown algae
analogous structures
- the specialized structures in the brown algae (ex: holdfasts, stipe, blades) that AROSE independently from similar features in plants
zooplankton
- UNICELLULAR organisms (zooplankton) that MOVE via cilia
- they have to HUNT & EAT stuff in order to get their ENERGY, they don’t photosynthesize
- most are PREDATORS that feed on bacteria & algae
- we see this IN CILIATES (in the subgroup alveolates)
tests
the porous shell of a foram
• Name Foraminiferans (Forams) means “little hole” for their porous shells (tests)
• Made of calcium carbonate
Chlorophytes
mostly freshwater and terrestrial species
• Can be unicellular, multicellular and/or colonial
- we see this in Green Algae (supergroup Archaeplastida)
colonial
- a colony of single-cell organisms is known as colonial organisms
- we see this in Green Algae (supergroup Archaeplastida) specifically in chlorophytes
Charophytes
closely related to land plants
- we see this in Green Algae (supergroup Archaeplastida)
plasmodium (syn. syncytium)
• Form a mass called plasmodium (syn. syncytium), a single-celled cytoplasm containing many nuclei
- the parasitic organism that causes malaria
- we see this in plasmodial slime moulds (within the slime moulds (Mycetozoans) within the clade amoebozoans & in Apicomplexans!
sporozoites
specialized cells that INVADE host cells
- ex: Plasmodium, parasite that causes malaria
- we see this in Apicomplexans (within the subgroup Alveolates)
micronucleus
exchange of genetic material during conjugation
- we see this in the Ciliates (within the subgroup alveolates)
macronucleus
transcriptional active (produces RNA) - we see this in the Ciliates (within the subgroup alveolates)
Describe how Fungi can be mutualists
Endophytic fungi associate with plants
• Not limited to roots (compared to mycorrhizae), found in all plant tissues
• Most are ascomycetes
• Provide a range of beneficial effects including producing anti-herbivory
toxins, increasing heat/drought/heavy metal tolerance
Animal mutualists
• Some occur in the guts of animals (chytrids in sheep)
• Ant colonies farming fungi for nutrients (Leaf cutter ants)
Describe Lichens
- SYMBIOTIC relationships between an ascomycete (or sometimes a basidiomycete or glomeromycete) fungus and a green alga and/or cyanobacterium
- GROW ON various SUBSTRATA: rocks, soil, trees, metal, concrete, plant leaves
- Most are TERRESTRIAL but some are AQUATIC
- ~13,000 species of lichens identified to date
What are the 3 growth forms of Lichens?
- fruticose (shrublike)
- foliose (leaflike)
- crustose (encrusting)
How do Lichens reproduce?
- sexual via fungal life cycle
* asexual via soredia, fragmentation, other specialised structures
Describe Eukaryotes
• Eukaryotes: protists, plants, animals, fungi
• Have membrane-BOUND organelles
• Have a NUCLEUS
• Have a CYTOSKELETON for support (Allows for asymmetrical cell forms)
- most are SINGLE-CELLED organisms
What does cytoskeleton that is for support in Eukaryotes allow for?
Allows for asymmetrical cell forms
Protists are the most abundant eukaryotic
lineages and are…
unicellular
Some protists can exist in…
colonies or be multicellular
What are the diverse nutritional modes of protists?
- Photoautotrophs, containing chloroplasts
- Heterotrophs
- Mixotrophs, both photosynthetic and heterotrophic (Have arisen independently in protist lineages)
What are the diverse reproductive cycles of protists?
- Asexual
- Sexually
- Alternating between 2N and N
How many supergroups are within Eukarya? AND how many unresolved protistan groups?
- 4 supergroups within Eukarya
* 2 unresolved protistan groups
What is endosymbiosis?
is a symbiotic relationship where one thing lives inside another
What did Mitochondria and Chloroplasts used to be?
- Mitochondria used to be a HETEROTROPHIC, O2 using prokaryote
- All derived from a common ancestor
- Chloroplasts used to be a PHOTOSYNTHETIC prokaryote
- Arose multiple times
Describe Primary endosymbiosis
engulfing of a photosynthetic cyanobacterium by a heterotrophic eukaryote
When did the first transfer of photosynthesis from a prokaryote to a eukaryote occur?
in primary endosymbiosis
Describe Secondary endosymbiosis
a heterotrophic eukaryote ate a photosynthetic eukaryote
• Usually a red or green algae
• Spread photosynthesis to 3 out of 4 supergroups
• Photosynthetic eukaryote becomes the new plastid
What is the Supergroup Excavata? What are the 3 monophyletic clades?
• Excavates have an “excavated” feeding groove, based on cytoskeletal morphology
- 3 monophyletic clades:
- Diplomonads
- Parabasalids
- Euglenozoans
Describe the features of Diplomands
Mitochondria: Mitosomes (lack functional ETC)
Metabolism: Anaerobic pathways
Nutritional Mode: Parasites (ex. Giardia intestinalis, “Beaver fever”)
Nuclei: 2 equal sized
Flagella: Multiple
Other features: *
Describe the features of Parabasalids
Mitochondria: Reduced, called hydrogenosomes
Metabolism: Anaerobic, releasing H as byproduct
Nutritional Mode: Parasite (ex. Trichomonas vaginalis, STI)
Nuclei: *
Flagella: 2
Other features: Undulating membranes
Describe the features of Euglenozoans
Mitochondria: Single, large (Kinetoplastids)
Metabolism: *
Nutritional Mode: Predatory heterotrophs, autotrophs, mixotrophs, parasites
Nuclei: *
Flagella: Crystalline rod inside one of their flagella
Other features: Light detectors (Euglenids)
What is the Supergroup SAR? What are the 3 monophyletic clades?
- Very large group defined by DNA similarities
- 3 monophyletic clades:
- Stramenopiles
- Alveolates
- Rhizarians
Describe the diagnostic features of the Supergroup Stramenopiles
2 Flagella: 1 with numerous hairlike projections, 1 smooth
Describe the diagnostic features of the Supergroup Alveolates
Membrane-bound sacs (Alveoli) under the plasma membrane
Describe the diagnostic features of the Supergroup Rhizarians
Amoebas and flagellated protists with pseudopodia
Describe the Diatoms
- within the supergroup SAR: subgroups Stramenopiles
- Unicellular algae with a silica covering made of two pieces
- ~10,000 species
- Phytoplankton
- Main cause of shellfish poisoning due to the toxins they produce
- Can result in huge “blooms”
Describe the Brown Algae
- within the supergroup SAR: subgroups Stramenopiles
- Multicellular, mostly marine “seaweeds’
- Alternation of generations life cycle
- Brown due to carotenoids (accessory pigment) in their plastids
- Have specialised structures such as
- Holdfasts – anchorage
- Stipe – “stem”
- Blades – “leaves”
- Above arose independently from similar features in plants -> analogous structures
What is included in the supergroup SAR: subgroups Stramenopiles?
- diatoms
- brown algae
- golden algae & oomycetes
What is included in the supergroup SAR: subgroup alveolates?
- dinoflagellates
- apicomplexans
- ciliates
Describe the Dinoflagellates
- within the supergroup SAR: subgroup alveolates
- Cells are reinforced by CELLULOSE PLATES
- Contains 2 flagella within grooves (they SPIN when they move)
- Photoautotrophic (through secondary endosymbiosis), mixotrophic and heterotrophic aquatic organisms
- Causes “RED TIDE”, blooms in the ocean
- Can produce TOXINS
Describe the Apicomplexans
- within the supergroup SAR: subgroup alveolates
- Unicellular parasites of animals
- Contains sporozoites, specialised cells that invade host cells
- Ex. Plasmodium, parasite that causes malaria
- Have complex life cycles with asexual and sexual stages and which require 1-2 hosts
Describe the Ciliates
- within the supergroup SAR: subgroup alveolates
- Unicellular organisms (ZOOPLANKTON) that move via cilia
- Most are PREDATORS that feed on bacteria and algae
• Have 2 nuclei:
- Micronucleus - Macronucleus
• Reproduce via binary fission
What are AND describe the 2 nuclei in the Ciliates
- Have 2 nuclei:
- Micronucleus -> exchange of genetic material during conjugation
- Macronucleus -> transcriptional active (produces RNA)
How do Ciliates reproduce?
Reproduce via binary fission
What is included in the supergroup SAR: subgroup rhizarians?
- radiolarians
- foraminiferans (forams)
- cercozoans
Describe the Radiolarians
- within the supergroup SAR: subgroup Rhizarians
- Have delicate, SYMMETRICAL internal silica skeletons
- Pseuodpodia RADIATE from central body
- Mostly marine
Describe the Foraminiferans (Forams)
- within the supergroup SAR: subgroup Rhizarians
- Name means “little hole” for their porous shells (TESTS)
- Made of calcium carbonate
- PSEUDOPODIA extend through the pores for moving, feeding, and building the shell
- Aquatic, both marine and freshwater
- 90% of all forams are known FROM FOSSILS
Describe the Cercozoans
- within the supergroup SAR: subgroup Rhizarians
- Amoeboid and flagellated protists
- Common in marine, freshwater and soil ecosystems
- Heterotrophs (most) and parasites (many) and predators
What is unique about the Supergroup Archaeplastida? AND what is included?
• Composed of red algae, green algae and land plants
- Monophyletic clade
- common ancestor is an ancient protist that engulfed a cyanobacterium
Describe Red Algae
- within the Supergroup Archaeplastida
- ~600 species, red due to accessory pigment PHYCOERYTHRIN
- ABSORBS blue and green light
- Most ABUNDANT large algae in tropical marine habitats
- Multicellular, still considered “seaweeds”
- Commonly EATEN as a food source (Nori in sushi)
Describe Green Algae
- within the Supergroup Archaeplastida
- ~7000+ species
- Single-celled and multicellular
- Green due to CHLOROPHYLL in their chloroplasts
- Paraphyletic group:
- Chlorophytes
- Charophytes
Describe the paraphyletic group within the Green Algae
• Chlorophytes -> mostly freshwater and terrestrial species
- Can be unicellular, multicellular and/or colonial
• Charophytes -> closely related to land plants
Describe the Supergroup Unikonts AND the 2 major clades
- Includes animals, fungi, and some protists
- Two major clades:
- Amoebozoans
- Opisthokonts
What is each clade within the Supergroup Unikonts supported by?
molecular systematics and analysis of myosin proteins
- However, we don’t know the root of the Eukaryotic tree at the Unikonts
- We don’t know which group of Eukaryotes came first
Describe the Supergroup Unikonts: Clade Amoebozoans AND what is included
• Includes amoebas with lobe or tube-shaped pseudopods
- slime moulds (Mycetozoans)
- tubulinids
- entamoebas
Describe the Slime Moulds (Mycetozoans, formerly Myxomycota)
- within the supergroup Unikonts: clade Amoebozoans
- Produce fruiting bodies that aid in spore dispersal
- But no longer considered fungi -> convergent evolution
• Occur in two forms:
- Plasmodial slime moulds
- Cellular slime moulds
Describe the Plasmodial slime moulds form
- Form a mass called plasmodium (syn. syncytium), a singlecelled cytoplasm containing many nuclei
- Produced via mitosis that does NOT end in cytokinesis
- Extends pseudopodia through substrate to feed (phagocytosis)
- When environment dries, stops expanding and produces sporangia
Describe the Cellular slime moulds form
Feeding stage consists of solitary cells but join together when food is depleted, forming aggregated amoebas that produce stalked sporangia for spore dispersal
Describe the Tubulinids
- within the supergroup Unikonts: clade Amoebozoans
- Unicellular protists found in soil and aquatic environments
- Most are heterotrophs, eating bacteria and other protists
- Ex Amoeba proteus
- Free-living
Describe the Entamoebas
- within the supergroup Unikonts: clade Amoebozoans
- Parasites, infecting vertebrates
- Ex. Entamoeba histolytica causes amoebic dysentery, which is spread by contaminated water
What are the 2 major groups of protists that remain uncertain AND why?
- So hard to isolate and culture, grouping them based on morphology and/or DNA is near impossible
- Haptophytes
- Cryptomonads
