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BIOL 322 > Final Exam > Flashcards

Final Exam Flashcards

1
Q

Six eukaryotic supergroups

A
  • Amebozoa
  • Opisthokonta (together with Amebozoa forms the Unikonta)
  • Archaeplastida
  • Excavata
  • SAR
  • CCTH/Hacrobia
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2
Q

Defining features of the Opisthokonts

A
  • Flagellated stages move with flagella towards the back, rather than the front
  • Proposed that ancestor had one flagellum arising from single centriole
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3
Q

Which groups comprise the Holozoa of the Opisthokonts?

A
  • Ichthyosporea
  • Capsaspora
  • Choanoflagellates
  • Metazoa (animals)
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4
Q

What are the Choanoflagellates?

A
  • Closes relatives to animals (have very similar cells to sponges - called “choanocytes”)
  • May have role in multicellularity
  • Silicate lorica basket - flagellated with actin-based microvilli to create current that brings bacteria to it
  • Called the “collared flagellates”
  • Mostly marine, some freshwater
  • Very common in plankton, but so small they tend to pass through plankton nets
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5
Q

What are the Capsaspora?

A
  • Opisthokonts, Holozoa
  • Filose amoeboid cell
  • Symbiotic - found in snails
  • Independent lineage from choanoflagellates
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6
Q

What are the Ichthyosporids?

A
  • Opisthokonts, Holozoa
  • Commensals or parasites, all in association with animals
  • Trophic (=feeding) stages are multinucleated cells with many large vacuoles
  • CHITIN cell wall present
  • Propagate via (opisthokont) flagellated stages, walled spores, or lobose amoebae
  • Important pathogens of fish
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7
Q

What are the general characteristics of the fungi? What groups does the fungi comprise?

A
  • Chitin cell wall and lack of flagella (ancestor likely lost)
  • Comprises Holomycetes, Microsporidia, Ascomycetes
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8
Q

Describe the Ascomycota

A
  • Yeasts (budding)
  • Medically relevant (Candida albicans)
  • Economically relevant (Saccharomyces cerevisiae)
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9
Q

Describe the Microsporidia

A
  • Fungi
  • Important pathogens of insects
  • Role as human pathogens is increased as a consequence of AIDS epidemic and use of immunosuppressant drugs (most infections GI, but ocular, respiratory, or muscular infections can occur also)
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10
Q

What are the Rozellids? What group are they a part of? What is unique about this group of fungi?

A
  • Rozellids are part of Cryptomycota
  • Found in freshwater, marine, and soil environments
  • Cryptomycota redefine fungi through their LACK of a chitin cell wall and PRESENCE of a flagellum
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11
Q

What are the nucleariids?

A
  • Basal relative of fungi
  • Filose amoebae (=shape)
  • Discoid mitochondrial cristae, completely atypical for Opisthokonts
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12
Q

What are the two defining features of the Amoebozoa?

A
  • Tubulinea: United by possession of tubular pseudopodia (filose - fine, thin pseudopods; lobose - thick, wide pseudopods)
  • Unidirectional (monoaxial) cytoplasmic streaming (movement of things in the cytoplasm) –> cytoplasm always moves forward
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13
Q

Describe the Amoeba and Giant Amoeba species

A
  • Can be very large
  • Have single polygenomic nucleus - nuclei divide simultaneously = a “plasmodium”
  • Plasmodium = acellular, multinucleate mass; often enclosed by a slime sheath; often brightly coloured
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14
Q

Describe slime molds

A
  • Amoebozoa
  • Mycetozoans
  • Produce spores, share habitats with fungi
  • Not saprophytic like fungi, they are bacterial predators
  • Pseudopodia of amoeboid stages are often filose
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15
Q

What is a myxomycete?

A
  • Plasmodial slime mold
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16
Q

What are dictyostelids?

A
  • Amoebozoa
  • Cellular slime molds - model system for cellular differentiation in eukaryotes
  • Trophic stages generally amoebae, seldom uniflagellate amoeboflagellates
  • Never form plasmodium
  • Evolution of multicellularity - spore and stalk (spores are released and divide; stalks won’t have progeny)
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17
Q

Describe the Archaeplastids

A
  • Invented photosynthesis
  • Morphological characteristics: Descendants of ancestral host cell that took up cyanobacterial endosymbiont (primary endosymbiosis is key feature of archaeplastids)
  • Molecular characteristics: Many endosymbiotic genes transferred from plastid to ancestral host lineage; process = endosymbiotic gene transfer (EGT) - when this is shared between hosts, most likely explanation is that it diverged prior to divergence of lineages
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18
Q

What are the three groups of the Archaeplastids?

A
  • Glaucophytes (cyanobacterial symbiont)
  • Viridiplantae (green algae and land plants)
  • Rhodoplantae (red algae)
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19
Q

Describe the viridiplantae

A
  • Chlorophytes (green algae)

- Streptophytes (land plants and some algae)

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20
Q

What are micromonas?

A
  • Archaeplastids, Viridiplantae
  • Very simple; may be smallest eukaryote
  • One flagellum; no scales
  • Very common and successful despite small size
  • Model green algae
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21
Q

What are volvox?

A
  • Archaeplastids, Viridiplantae
  • Green algae (Chlorophyceae)
  • Between 500 to several thousand individual cells in periphery of mucilaginous shell
  • Cells toward front have larger eyespots; daughter colonies tend to develop closer to the back
  • Model system for multicellularity in algae and plants
  • Unicellular and multicellular stages
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22
Q

Describe the Glaucophytes

A
  • Small group, rare, only in fresh water
  • Contain blue-green plastids often called cyanelles
  • Info on Archaeplastid origin
  • Photosynthetic
23
Q

What are the Rhodoplastids?

A
  • Red algae
  • Lack flagella and flagellar roots in all life history stages
  • Red plastids
  • Most forms multicellular (likely arose early in evolution)
24
Q

Describe the Cyanidiophytes

A
  • Rhodoplastids
  • Unicellular
  • Thick proteinaceous cell walls
  • Often one single cup-shaped plastid
  • Inhabit extreme environments
  • Colour like that of cyanobacteria (i.e., not red!)
25
Q

Provide an example of red algae

A
  • Bangiomorpha pubescens - oldest multicellular eukaryote fossil reported: 1200MYA
  • May be oldest clearly eukaryote fossil
  • Very similar to examples of moderm red algae (e.g., Bangia atropopurea)
  • Definitely an Archaeplastid - Archaeplastid symbiosis happened very early in lineage
26
Q

What are the Excavata and what is the excavate hypothesis?

A
  • Eukaryotic supergroup with very diverse morphology

- Possess a ventral feeding groove

27
Q

What are the Euglenozoa?

A
  • Excavates
  • Some free-living (photosynthetic)
  • Some pathogens (Leishmania; Trypanosoma)
28
Q

What causes Nagana?

A
  • Excavates
  • Trypanosoma species transmitted by the Tsetse fly
  • Cattle die from severe anemia
29
Q

What causes African Sleeping Sickness?

A
  • Excavates
  • Trypanosoma brucei
  • Transmitted by Tsetse fly
  • Causes damage to vascular, immune, CNS, and inflammation of brain
  • Livestock can be reservoirs
30
Q

What is Naegleria fowleri?

A
  • Excavates
  • Amoeba, free-living in warm bodies of fresh water
  • Enters body of swimmers through nose
  • Infects neural tissue (brain and spinal cord)
  • Primal Amoebic Meningoencephalitis
  • Feed on neural tissue
31
Q

What are the metamonads and what are their defining characteristics?

A
  • Excavata
  • Defined by conspicuous Golgi and cytoskeletal apparatus
  • Hydrogenosomes, no mitochondria
  • Flagella, but NO GROOVE (exception)
  • Almost entirely parasitic/symbiotic
  • Anaerobic/microaerophilic (Trichomonads and Hypermastigotes)
32
Q

Describe Trichomonas vaginalis

A
  • Excavate, Metamonad
  • Common parasite
  • Infects genital tract
  • Generally benign, but can increase risk of HIV or cancer
33
Q

Describe Hypermastigotes

A
  • Excavate, metamonad
  • Obligate symbionts of wood-eating cockroaches and termites
  • Anaerobe
  • Very large cells, 100-300um
  • Many rows of flagella with basal bodies arranged perpendicularly to parabasals (unknown why)
34
Q

What are the diplomonads?

A
  • Excavates (metamonad)
  • Small group
  • Many species have two karyomastigonts (symmetry in middle of cell). Resmble “double” organisms
  • Highly diverged
  • Many parasitic (Giardia, Spironucleus - hold in head disease in fish)
35
Q

Describe the supergroup CCTH

A
  • Haptophytes, Cryptophytes are united with two previously unplaced groups, the Telonemids and Centrohelids
36
Q

Describe the haptophytes

A
  • Not large group in terms of number of species but very ecologically important
  • Mostly marine, some freshwater
  • 3rd major group of primary producers in ocean, after diatoms and dinoflagellates
  • Produce DMS (cloud condensation molecule) and therefore are implicated in cloud formation and global weather patterns
  • Generally flagellated forms, some species coccoid (often embedded in mucous, filamentous or colonial)
  • Have calcium carbonate shells
  • Blooms fix lots of carbon; lots of carbon in shells as well (acid will dissolve shells, releasing carbon into atmosphere)
37
Q

Describe the cryptomonads

A
  • Haptophyte
  • Hard to find/study
  • Very small and inconspicuous; delicate
  • Usually free-living flagellates, but forms encapsulated in mucous also exist
  • Most photosynthetic, a few are not
  • Both freshwater and marine forms
  • Common in cold water and high latitudes
  • Tolerate low levels of light, therefore found in deep ocean
  • Cryptomonas sp. is only in fresh water and lost photosynthetic ability (but not plastid)
38
Q

Describe the Telonemids

A
  • High diversity
  • Small cells, non-photosynthetic
  • TWO posterior flagella
39
Q

Describe the centrohelid heliozoans

A
  • Rounded body surrounded by stiff axopodia (phagocytic pseudopodia containing MTs)
  • Axopodia supported by internally interlinked MTs arranged in hexagonal patterns
40
Q

What composes the SAR supergroup?

A
  • Stramenopiles, Alveolates, and Rhizaria

- So large that there is no single uniting feature (even within groups)

41
Q

What is the morphological feature of the Rhizaria?

A
  • United by presence of filose or reticulate pseudopodia (not a strong characteristic)
  • Otherwise, shows huge diversity of size and body type
42
Q

What are the three major groups of Rhizaria?

A
  • Cercozoa (endomyxa, filosa)
  • Foraminifera
  • Radiozoa
43
Q

Describe the cercozoa

A
  • Part of Rhizaria
  • Diverse group with photosynthetic flagellates (Chlorarachniophytes), heterotrophic flagellates (Cercomonas) or organisms covered in shells (e.g., Euglypha - very large protective shell; predatory!)
44
Q

Describe Foraminiferans

A
  • Large group, part of Rhizaria
  • Some of the largest protists are in group. Xenophytes up to 25cm! (although most others are 6-12um)
  • Still unicellular - multinucleate (plasmodium)
  • Mostly marine; some colonize freshwater and terrestrial habitats
  • “Pave sea floor” because they are so abundant
  • Skeletons classified according to material they are made of: glycoprotein (organic shells); sand grains glued together (glue is organic matrix, calcium carbonate, or both); calcium carbonate
  • Make around 1/4 of global calcium carbonate
  • Skeletons can have compartments
  • Nummulites (sp.): Fossil forams, main component of rock used to make Egyptian pyramids
45
Q

Describe the Radiozoa

A
  • Always planktonic, always marine
  • Exist at all depths, including deep sea
  • General morphology of group reflects adaptation to planktonic lifestyle (very diverse morphology)
46
Q

Describe the Stramenopiles

A
  • Stramenopiles (straw hair) refers to typical tripartite mastigonemes (hair/extensions) of group
  • Flagella with three hairs on end
  • Mastigonemes reverse thrust of flagellum: beating anterior flagellum pulls cells forward
  • Stramenopiles = heterokonts
  • Heterokonts have two flagella that differ in unique way. One if long, forward-directed. Other is short, smooth, and generally directed towards back
  • Place photosynthetics together; stramenochromes/sloomycetes
47
Q

Describe the diatoms

A
  • Stramenochromes
  • Ubiquitous in marine and freshwater
  • One of the largest protist groups
  • Responsible for 20% of global primary production
  • Have two parts: Diatom Frustule (cells encased in unique type of siliceous (=glass) wall that takes form of box with overlapping lid
  • When nutrients are low, diatoms sink and create large sections of ocean floor covered in fossil siliceous remnants of diatom frustules - large carbon sink
48
Q

Describe brown algae

A
  • Stramenochromes
  • Microscopic to large kelp forests
  • No unicellular species
  • Huge primary producers in coastal areas, especially temperate and polar regions
  • Not directly related to red/green algae
49
Q

What are sloomycetes?

A
  • Oomycetes
  • Plant pathogens
  • Non-photosynthetic heterokonts
  • Very similar to fungi (look like fungi and infects like fungi) = horizontal gene transfer!
  • This facilitated evolution of plant parasitism
50
Q

What are sloomycetes responsible for?

A
  • Ireland potato blight

- Phytophthora infestans (likes wet cool summers)

51
Q

What are the alveolates? What is their defining feature? What are the three major groups?

A
  • Alveolae are flattened vesicles that lie below the plasma membrane
  • Very robust in phylogenetic trees
  • Three groups: ciliates, dinoflagellates, apicomplexa
52
Q

Describe the ciliates

A
  • Alveolate
  • Many small flagella-cilia
  • Mainly aquatic
  • Nuclei of two types: Micronucleus (diploid, transcriptionally inactive, germ-line); macronucleus (polygenomic, transcriptionally active, control phenotype)
  • Ecology: harbour photosynthetic bacteria-algae symbionts; can be raptorial feeders (chase prey); some are filter feeders
  • Transformations: can transform into raptorial feeders when starved due to changes in transcription
  • Often live in guts of mammals as commensals, digest soluble carbohydrates or starch grains
53
Q

Describe the dinoflagellates

A
  • Alveolate
  • Both photosynthetic and non-photosynthetic species
  • All aquatic environments
  • Defined by presence of TWO flagellum (one transversal flagellum; one longitudinal flagellum)
  • Many also possess plates/scales
  • Cause red tides = phytoplankton blooms
  • Fix a lot of carbon
  • Two ways dinoflagellate blooms can be harmful: Toxins may act on fish and kill them or may accumulate in organisms; high densities of non-toxic cells in water may cause harm by decreasing oxygen levels and killing other aquatic life
54
Q

Describe the Apicomplexa

A
  • Alveolates
  • Almost entirely parasitic
  • Have “apical complex” (special set of organelles used to penetrate host cells; part of apicoplast - used to be chloroplast, but lost photosynthetic ability)
  • Possess remnant plastid, unusual golgi organization
  • Causes diseases of agricultural and human importance
  • Plasmodium - causes malaria (should target apicoplast to develop treatment)

BIOL 322 (2 decks)

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