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MICR 2420 > Microbial Diversity: Eukarya > Flashcards

Microbial Diversity: Eukarya Flashcards

1
Q

domain Eukarya is morphologically the most diverse of the 3 domains

A
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2
Q

Eukaryotes are a very diverse group, how are they classified?

A
  • All have a nucleus and membrane enclosed organelles but few are amitochondiate (lack mitochondria) and have few organelles

*believed they lost it, degenerative evolution

  • All descended from an ancestral cell that ungulfed a Protobacterium (Gram neg) bacterial endosymbiont - became a mitochondrion
  • Mitochondria conduct oxygenic respiration
  • all phototrophic eukaryotes arose from an acestral eukaryote cell that engulfed an ancestral photosynthetic bacteria (cyanobacteria) that became a chloroplast
  • chloroplasts condust oxygenic photosynthesis
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3
Q

Eukaryotes are classified into…

A
  • 8 different calsed; unicellular/microscopic forms dominate
  • based on DNA sequence comparisions and protein trees
  • sequence based calssification of eukaryotes has many challenges

*genomes are much larger (than prok) so many cases of reductive/degenerative evolution, convergent evolution

  • 50-90% of DNA sequences are non-coding
  • eukaryote evolution involved in serial endosymbiosis

*NO mitochondria in metamonada clade

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4
Q

describe the Opisthokont clade

A
  • animals, true fungi and microsporidia
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5
Q
A
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6
Q

what are choanoflagellates?

A
  • in the opisthokont clade
  • considered the mixxing link between animals and microbial eukaryotes
  • diverged most recently from animals (600 mya)
  • while genome seq reveleaed interesting similarities to modern eukaryotes:

*Five immunoglobulin/antibody genes - yet choanoflagellates have no immune systems

*Collagen, cadherin & integrin domains - yet choanoflagellates ahve no cytoskeleton, or matrix binding cells together

*tyrosine kinase genes - yet they are not knwon to communicate or signal intracellularly or intercellularly with each other

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7
Q

what does presence of a flagella differentiate

A

sets apart animals from protists and eukaryotes from prokaryotes

  • Prokaryotic flagellum has a basl body, hook and rigid filament, the hollow filament is composed of flagellin protein
  • eukaryotic flagellum has a basal body and flexible filament. the filament is packed with microtubes arranged in a 9+2 pattern
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8
Q

How do funig play essential roles in a diverse ecosystem

A
  • different species show vastly different forms - ex mushrooms (caps = fruting bodies that can weigh several pounds) to the mycelia of pathogens and the symbiotic partners of algae in lichens
  • fungi provide essential support for all communities of multicellular organisms
  • are natures recyclers: saprophytes
  • some fungi are pathogenic to animals and plants - others produce antibiotics and food products like wine and cheese
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9
Q

explain how fungi are natures recylers

A
  • ex: saprophytes
  • break down dead and decayng organic matter to release for other living thigns to suce
  • fungi recycle the biomas of wood and leaves which other orgnaisms may be unable to digest (ex: ligins, pectins)

*they are chemoorganoheterotrophs: draw energy from organic material

  • underground fungal filaments called mycorrhizae (plant symbionts) extend the root systems of most plants
  • within the ruminant digestive tract, fungi (and bacteria) ferment plant materials
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10
Q

what traits are common to most fungi

A
  • most fungi grow by extending hyphae into the substrate/food source

*hyphae grow at the tips forcing thier way into the substrate

  • hyphae: multinucleate ell filaments which branch extensively generating a mycelium

- cell walls contain chitin polymers of immense tensile strength, stronger than steel

  • membranes contain phospholipids and ergosterol an analog of cholesterol not found in animals or plants
  • absorptive nutrition: secretion of degradative enzymes into the extracellular environment and then absoroption of the broken down/simpler products/nutrients
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11
Q

describe fungal mycelium

A
  • a mass of extending braching hyphae
  • mycelia are the vegetative part of the gunfi; largest body mass - extend into and are hidden in the food substrate
  • spores are aerially displayed to allow for optimal dispersal, they are the reproductive part

(like the mold on an organe, thats the spore)

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12
Q

fungi can be unicellular or multicellular, give examples of uniellualr

A
  • unicellular fungi = yeast
  • reproduce asexually by budding
  • yeasts have no hyphae and mycelia
  • ex: Saccharomyces cerevisiae, Baker’s yeast, and Schizosaccharomyces pombe (and other species) Brewer’s yeast

*Canadida albicans is a unicellualr fungi - an opportunistic pathogen and can grow also as mycelia

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13
Q

describe sexual and asexual reproduction in yeast

A
  • some yeastas are asexual - never amte
  • others like Saccharomyces cerevisiae have a life cycle that alternates between haploid (1n) and diploid (2n) forms
  • haploids develop gametes (1n) for fertilization producing a 2n diploid zygote
  • dilpoids undergo meiosis, restoring the haplid form
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14
Q

why are unicellular fungi model organisms for study of eukaryote cell biology

A
  • have haploid genome
  • they are eukaryotes so can be used as a proxy to study mammalian cell process
  • saccharomyces cerevisae is used as a model organism, there are libraries where there genes have been mutated so you can do study for specific gene functin
  • use to study protein folding, vesicle trafficking, lipid biology
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15
Q

what is mycorrhizae

A
  • fungi involved in mutually beneficial and essential symbiotic relationships with plant roots
  • some species (armillaria) can spreaf for thousands of acres within forests and some are suspected to be over 8000 years old
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16
Q

how do plants communicate

A
  • using an ‘internet’ of fungus
17
Q

some fungi are pathogens, give examples of opportunistic fungi pathogens

A
  • Candida albicans – thrush, candida in humans
  • Pneumocystis jirovecii (formerly P. carinii) causes pneumonia
  • Chytridiomycota sp. – responsible for massive global frog die-off
  • Nosema species in bee colony collapse disorder
18
Q

what is Ophiocordyceps unilateralis

A
  • fungi that infects insects
  • ’ mind controlling’ fungi pathogen
  • fungal spores enter the ant’s bod through enzymatic damage to the chitin exoskeleton
19
Q

what are amoebas?

A
  • protists
  • look like amorphous blobs of jelly
  • able to move trhough production of pseudopods (false feet)

*cytoplamc motility is complex, involved actin polymerization/depolymerization (more oslid-more liquid form)

  • a few species are parasites of human/animals
  • most are free-living in soil and water - engluf prey (microbes) using phagocytosis
  • also act as environmental hosts for bacterial pathogens
    ex: listeria monoctogenes, mycobacterium
  • used as a model organism for study of animal phagocyte/macrophage cells (interaction with microbial pathogens, motility)
20
Q

some stories of amoeba in the news

A

-Naegleria fowlerii - brain eating amoeba, feed on environmental bacteria/microbes. If inhaled in water aerosoles they establish infection in the repsiratory tract, from there can cross the bbb and feed on brain tissues

21
Q

describe slime molds

A

protists

  • were thought of as fungi - hene mold

*instead have ccellulose not chitin in cell walls, aggregate to form multicelular structues

  • two kinds:

cellular slime molds:

  • E.g Dictyostelium discoideum
  • Individual cells remain single/cellular, but in a swarm (work as community, move together)
  • when unfavourable condiitons an come together in response to a signal, then aggregate to form a complex fruiting body (Fig 20.31)

Plasmodial slime molds

  • E.g Fuligo septica (Dog’s vomit mold),
  • The mass/swarm of cells comes together in response to a signal, but then fuse into a giant cell of full of many nuclei
22
Q

describe algae

A
  • all have chlorplasts
  • primary producers, most crucially aquatic and marine habitats
  • in aquatic and marine ecology the algae and photosynthetic bacteria are known as phytoplankton
  • have diverse lifestyles and morphologies - inlcude lichen symbionts
  • two major types: primary and secondary endosymbiotic algae
23
Q

describe the concept of primary and secondary endosymbiosis

A

primary

  • ancestral pre-eukaryote cell engulfed either
    • an acestral proteobacterium which became a mitochondrion (ancestor of modern protozoa, fungi, animal cells)
    • an ancestral phototrophic bacterium/cyanobacterium which became the chloroplast
    • all are phototrophs

Secondary

  • eglufment of a primary phtototrophic endosymbioent (ex algae) has been englufed by a mitochondrion containing eukaryote
  • distinguishing feature - the chloroplast is surrounded be 2 membranes from each event
24
Q

what is the rhodophyta clade

A
  • some algae grow in large sheets but are only 2 cells thick
  • red algae
  • contain commercially valuable polymers ex: sulfated polygalactans (include agar and agarose)

several kinds are human food sources (ex Phorphyra) - mori used to wrap sushi

25
Q

ex of alveolates

A
  • Dinoflagellates – phototrophs & predators
  • Apicomplexans – specialized parasites
26
Q
A
27
Q

what are diatoms

A

Secondary endosymbiotic algae

  • Unicellular algae with unique, protective bipartite shells / Frustules
  • made of silica (glass)
  • Frustules form some of the most beautiful forms found in nature
  • Cell division is interesting!
  • Dead diatoms sink to the sediment and form ‘diatomaceous earth’
28
Q

what are dinoflagellates & Red tides

A
  • part of alveolate clade
  • major group of marine phytoplankton
  • algal symbionts and critical endosymbionts of reef-building corals (provide organic components to other organisms)
  • Characteristic feature: possess 2 flagella, one is wrapped around the cell in a specialized groove
  • some supplement photosynthesis through prodation (heterotrophy)
  • some possess carotenoid pigments that confer a red colour, blooms cause red tise that releases toxins causing shellfish posioning and death
29
Q

what are apicomplexans

A
  • alveolates
  • animal parasitesex Plasmodium falciparum
  • spore (oocyst)-forming Cryptosporidium gondii and Toxoplasma sp.
  • Malaria causing, insect-vector transmitted Plasmodium sp.

-Have undergone extensive reductive evolution

Possess two important/characteristic organelles:

  • ‘Apical Complex’ which the parasites use to attach to & gain entry into host cells.
  • Apicoplast – for lipid metabolism

**Toxoplasma gondii, a mind-controlling parasite, oocysts are transmitted in cat feces; parasite cells can cross placenta barrier and harm fetus

30
Q

what is Plasmodium falciparum

A
  • best known apicoplexans
  • requires both the insect vector and animal host for completion of the life cycle
  • causative agent of human malaria
  • transmitted via saliva of the blood-feeding Anopheles sp. mosquitoes

*undergoes different development stages in the vector’s gut and salivary glands

  • effective control must involve target both the parasites and vectors
  • in the human host the parasite has a complex lifecycle with several different stages in the liver and RBC

*can breach the placenta and brain barriers

31
Q

describe protozoa/protists

A
  • most are harmless free-living protists and commensalas in guts of animals
  • are voracious feeders of other microbes including bacteria
  • few species cause serious/ deadly animal diseases
  • ex:
  • Cyst-forming Entamoeba histolytica – amoebic dysentery, liver abscesses, etc
  • Giardia sp – feces contaminated water, cause severe diarrhoea, cramps
32
Q

what are trypanosomes

A
  • cause some of the most gruesome and debilitating condiitons
  • They are obligate parasites; are transmitted by insect vectors
  • They consist of an elongated cell with a single flagellum.
  • The trypanosome has a unique organelle called the “kinetoplast”
  • Specialized ‘part’ of the parasite mitochondria
33
Q

what is Leishamia species

A

Ex f protezoa/protists

Leishmania species – cause leishmaniasis

  • transmitted by sandflies vectors)
  • affects skin, mucous tissues, cartilage, heart, decay of extremities, death

MICR 2420 (29 decks)

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