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Biology 170 > Chapter 28: Protists > Flashcards

Chapter 28: Protists Flashcards

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1
Q

Protist

A
  • Mostly unicellular group of eukaryotes informally known as protists
  • Most eukaryotes are singe-celled organisms
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2
Q

Structural and Functional Diversity

A
  • Most protists are unicellular, however some colonial and multicellular
  • Diverse in nutrition
  • Diversity thought to have arisen from endosymbiosis
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3
Q

Mixotroph

A

Combines photosynthesis with heterotrophic nutrition

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4
Q

Endosymbiosis

A

Relationship between two species in which one organism lives inside the cell or cells of another organism

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5
Q

Secondary endosymbiosis

A
  • Protist was ingested in food vacuoles of heterotrophic eukaryotes and became endosymbionts themselves
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6
Q

Diplomonads

A

Reduced mitochondria called mitoses; organelles lack functional electrons transport chains; many are parasites

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7
Q

Parabasalids

A
  • Reduced mitochondria; generate some energy anaerobically

- Example is T. vaginalis

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8
Q

Euglenozoans

A

Belong to diverse clade that includes predatory heterotrophs, photosynthetic autotrophs, mixotrophs, and parasites; presence of rod with either spiral or crystalline structure inside each of their flagella

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9
Q

Kinetoplastids

A
  • Single, large mitochondrion that contains organized mass of DNA called kinetoplast; feed on prokaryotes in freshwater, marine, moist terrestrial ecosystems
  • Trypanosoma (sleeping sickness–evade immune system quite easily)
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10
Q

Bait-and-Switch

A
  • Surface coated with millions of single protein; immune system can recognize these
  • New generation of parasite switches to another surface protein with different molecular structure
  • Prevents host from obtaining immunity
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11
Q

“SAR” Clade

A
  • Proposed based on whole genome DNA sequence analyses

- Stramenopiles, alveolate, and rhizarians to form a monophyletic supergroup

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12
Q

Stramenopiles

A
  • Important photosynthetic organisms
  • Name refer to characteristic flagellum with numerous fine, hairlike projections
  • Three groups: diatoms, golden algae, and brown algae
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13
Q

Diatoms

A
  • Unicellular algae that have unique glass-like wall made of silicon dioxide embedded in organic matrix
  • Can withstand immense amounts of pressure
  • Highly diverse and populated
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14
Q

Golden Algae

A
  • Color results from yellow/brown carotenoids

- Cells are biflagellate (both flagella attached near one end of cell)

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15
Q

Brown Algae

A
  • Multicellular; most are marine
  • Common along temperate coasts
  • Holdfast: Rootlike anchor
  • Stripe: Supports leaflike blades
  • Analogous to plants
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16
Q

Alternation of Generations

A
  • Alternation of haploid and diploid forms
  • Present in brown algae
  • Haploid form –> Releases male and female gametes –> Gametes recombine to form haploid form again
  • Isomorphic: Sporophytes and gametophytes look similar to each other
  • Heteromorphic: Sporophytes and gametophytes are structurally different
17
Q

Alveolates

A
  • Membrane-enclosed sacs just under the plasma membrane

- Abundant in many habitats and include wide range of photosynthetic/heterotrophic protists

18
Q

Dinoflagellates

A
  • Reinforced by cellulose plates; flagella located in grooves in armor and spin to propel
  • Important species include plankton, photosynthetic bacteria
  • Blooms: May create “red tide,” toxins produced capable of killing invertebrates and fishes
19
Q

Apicomplexans

A
  • Parasites of animals; attack virtually all animal species
  • Plasmodium: In humans, reproduce in liver and emerge in blood cells before bursting (alternation of generations occurs here too )
20
Q

Ciliates

A
  • Large/varied group of protists named for their use of cilia to move and feed
  • Genetic variation is induced by conjugation (two individuals exchange haploid micronuclei but do not reproduce)
21
Q

Rhizarians

A
  • Many are amoebas, some radiolarian, forams, cercozoans
22
Q

Amoebas

A

Move about by means of pseudopodia (extension that bulges from anywhere on cell surface )

23
Q

Radiolarians

A
  • Delicate, intricately symmetrical internal skeleton made of silica
  • Pseudopodia radiate from central body, reinforced by microtubules
24
Q

Forams

A
  • Foraminiferans are named for porous shells (tests); consist of single piece of organic material hardened with calcium carbonate
  • 90% of all identified species are known from fossils
25
Q

Cercozoans

A
  • Large group of amoeboid and flagellated protists that feed using threadlike pseudopodia; common inhabitants of marine, freshwater, and soil ecosystems
26
Q

Closest relatives of land plants

A
  • Red and green algae
27
Q

Archaeplastida

A
  • Monophyletic group that descended from ancient protist that engulfed a cyanobacterium
28
Q

Red Algae

A
  • Reddish owing to photosynthetic pigment called phycoerythrin; most abundant large algae in warm coastal waters of tropical oceans
  • Most multicellular
  • Reproduce sexually; diverse life cycles with alternation of generations
29
Q

Green Algae

A
  • Structure and pigment composition much like chloroplasts of land plants
  • Divided into charophytes and chlorophytes
  • Grass green chloroplasts
30
Q

Charophytes

A
  • Algae most related to land plants
31
Q

Chlorophytes

A
  • Include more than 7,000 species
  • Various species live independently in aquatic habitats
  • 3 Different Mechanisms: Formation of colonies of individual cells, formation of true multicellular bodies by cell division and differentiation, and repeated division of nuclei without cytoplasmic division
32
Q

Life Cycle of Chlamydomonas

A
  • Mature cells are haploid and contain single cup-shaped chloroplast
  • Respond to nutrient shortage by developing into gametes
  • Gametes fuse to form diploid zygote
  • Fertilization occurs, forms zygote
  • Meiosis produces four haploid individuals that emerge and mature
  • Asexual reproduction can occur; daughter cells develop flagella and cell walls and emerge as swimming zoospores
33
Q

Unikonta

A
  • Extremely diverse supergroup of eukaryotes that includes animals, fungi, and some protists
  • Two major kinds: Amoebooans and ophisthokonts
34
Q

Amoebozoans

A
  • Includes species of amoebas hat have lob- or tube-shaped pseudopodia
  • Slime mold
  • Tubulinds
  • Entamoebas
35
Q

Opisthokonts

A
  • Highly variable

- Include choanoflagellates, nucleariids, animals, fungi

36
Q

Protists’ Role in Ecological Communities

A
  • Most protists are aquatic but can be found anywhere
  • Symbiotic protists (termite guts dissolve cellulose), parasites that have compromised economies of other countries (malaria)
  • Photosynthetic protists (producers)
  • Constitute roughly 50% of world’s photosynthesis

Biology 170 (9 decks)

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