Chapter 28: Protists Flashcards
(36 cards)
1
Q
Protist
A
- Mostly unicellular group of eukaryotes informally known as protists
- Most eukaryotes are singe-celled organisms
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
3
Q
Mixotroph
A
Combines photosynthesis with heterotrophic nutrition
4
Q
Endosymbiosis
A
Relationship between two species in which one organism lives inside the cell or cells of another organism
5
Q
Secondary endosymbiosis
A
- Protist was ingested in food vacuoles of heterotrophic eukaryotes and became endosymbionts themselves
6
Q
Diplomonads
A
Reduced mitochondria called mitoses; organelles lack functional electrons transport chains; many are parasites
7
Q
Parabasalids
A
- Reduced mitochondria; generate some energy anaerobically
- Example is T. vaginalis
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
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)
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
11
Q
“SAR” Clade
A
- Proposed based on whole genome DNA sequence analyses
- Stramenopiles, alveolate, and rhizarians to form a monophyletic supergroup
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
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
14
Q
Golden Algae
A
- Color results from yellow/brown carotenoids
- Cells are biflagellate (both flagella attached near one end of cell)
15
Q
Brown Algae
A
- Multicellular; most are marine
- Common along temperate coasts
- Holdfast: Rootlike anchor
- Stripe: Supports leaflike blades
- Analogous to plants
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
Cercozoans
- Large group of amoeboid and flagellated protists that feed using threadlike pseudopodia; common inhabitants of marine, freshwater, and soil ecosystems
26
Closest relatives of land plants
- Red and green algae
27
Archaeplastida
- Monophyletic group that descended from ancient protist that engulfed a cyanobacterium
28
Red Algae
- 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
Green Algae
- Structure and pigment composition much like chloroplasts of land plants
- Divided into charophytes and chlorophytes
- Grass green chloroplasts
30
Charophytes
- Algae most related to land plants
31
Chlorophytes
- 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
Life Cycle of Chlamydomonas
- 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
Unikonta
- Extremely diverse supergroup of eukaryotes that includes animals, fungi, and some protists
- Two major kinds: Amoebooans and ophisthokonts
34
Amoebozoans
- Includes species of amoebas hat have lob- or tube-shaped pseudopodia
- Slime mold
- Tubulinds
- Entamoebas
35
Opisthokonts
- Highly variable
| - Include choanoflagellates, nucleariids, animals, fungi
36
Protists' Role in Ecological Communities
- 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
