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What genes for phylogeny of eukaryotes?
18S rRNA genes for phylogeny of eukaryotes
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How are phylogenies constructed?
Phylogenies have been constructed byt aking into account other genes (eg. tubulin, RNA polymerase, and ATPase)
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What do amitochondriate eukaryotes have instead of a mitochondria?
Mitosomes and hydrogenosomes
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What are mitosomes?
- Reduced form of mitochondria
- Derived from mitochondria- that does not have enzyme of the TCA cycle and does not have a respiratory chain
- Thney are involved in maturation of iron-sulfur cluster containing proteins
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What are hydrogenosomes?
- Present in eukaryotes whose metabolism is strictly fermentatie
- It caries the oxidation of pyruvate to H2, CO2 and acetate
- Sometimes H2-consuming endosymbiotic bacteria are also present (methanogens)
- Secondary endosymbiosis
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What is 'encysted'?
Some species of protists are able to differentiate into cysts, becoming encysted
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What are cysts similar to?
Cysts are similar to the endospore produced by prokaryotes
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What do cysts do?
- Help protect the cells against deleterious environmental conditions
- Help survive long period of starvation and/or dessication
- Help survive infection by prokaryotes
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What are diplomonads and Parabasaids?
- Unicellular
- Flagellated
- Lacks chloroplasts
- Live on anoic habitats
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What are diplomonads?
- Have 2 nuclei of equal size
- Have mitosomes (degenerated mitochondria)
- Key genera: giardia (causes giardiasis)
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What are Parabasalids?
- Contain a parabasal body (structural support to the golgi complex)
- Lack micochondria, but have hydrogenosomes for anaerobic metabolism
- Live in the intestinal and urogenital tract of animals as parasites or symbiotins
- Key Genera: Trichomonas
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What is Trichomonas vaginalis?
- Parabasalid
- STDs in humans: most common parasitic infection in well developed countries
- Does not form cyst, does not survive well outside the host (adapted to sexual transmission)
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What are Euglenozans?
- Unicellular flagellated eukaryotes
- ie Kinetoplastids
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What are kinetoplastids?
- Named for the presene o the kinetoplast, a mass of DNA present in their single large mitochondrion
- Live primarily in aquatic habitats feeding on bacteria
- Some species cause serious diseases i humans
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What is trypanosoma brucei?
- A kinetoplastid
- Cause African sleeping sickness, a chronic and usually fatal infection
- Lives and grows in the blood stream, infect the central nervous system during the later stage
- Transmitted by the tsetse fly
- The single flagellum is englosed in a membrane flap
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What are Euglenids?
- Nonpathodenic and phototrophic
- Contain chloroplasts, can exist as heterotrophs; will lose its chloroplast if incubated in the dark for a long term
- Can feed on bacteria by phagocytosis
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What are alveolates?
- Characterized by the presence of alveoli, which are sacs underneath the cytoplasmic membrane
- May function to help cells maintian osmotic balance
- In paramecium: contractil vacuole
- Members are ciliates, dinoflagellates, and apicomplexans
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What are ciliates?
- Possess cilia at some stage of their life
- Most widely distributed gnera are paramecium
- Use cilia for motility and to obtain food
- Ciliates have two nuclei (macronucleus and micronucleus)
- During conjugation- sexual reproduction- two paramecia exchange micronuclei
- Some ciliates are animal parasites, some are animal symbiotins (in the rumen)
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How do ciliates reproduce?
Two paramecia exchange micronuclei
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How many nuclei does a paramecia have?
2: macronucleus and micronucleus
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How do ciliates use cilia?
For motility and to obtain food
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What are dinoflagellates?
Divers marine and freshwater phototrophic organisms
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What is special about dinoflagellates?
- Have two flagella with different insertion points on the cell:
- Transverse flagellum
- Longitudinal flagellum
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What are dense suspensions of dinoflagellates called?
Red tides
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How do dinoflagellates poison humans?
- Associated with human poisoning (paralytic shellfish poisoning)
- Accumulation of toxic dinoflagellates in mussels
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What is Pfiesteria piscicida?
It is a genus of toxic dinoflagellate responsible for massive fish kills: spores infect fish, germinates, destroy tissue
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What do some dinoflagellates secrete?
Some secret neurotoxins
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Where do dinoflagellates reach very high numbers?
In warm, polluted water dinoflagellates can reach very high numbers
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What are apicomplexans?
- Obligate parasites of animals
- Complex life cycle
- Contain apicoplasts, degenerate chloroplasts that lack pigments and phototrophic capacity, but still carry many anabolic pathways
- Cause severe desiease such as malaria (Palamodium), toxoplasmosis (toxoplama), and coccidiosis (Eimeria)
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What are the three stages of amicomplexans life cycle?
- Sporozoite (transmission)
- Gameotoyte (sexual reproduction)
- Other stage
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What causes malaria
Plamodium
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What causes toxoplamosis?
Toxoplama
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What causes coccidiosis?
Eimeria
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How does toxoplasma gondii effect rats?
- Rats infected with the brain paraside Toxoplasma gondii approach the cat urine odors they typically avoid
- Toxoplasma infection alters neural avticity in limbic brain areas necessary for innate defensive behavior in response to cat odor
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What are stramopiles?
- All have flagella with many short hairlike extensions
- Chemoheterotrophs and phototrophic members
- Oomycetes, diatoms, golden algae, and brown algae
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What are oomycetes?
- Chemoheterotrophs
- Also called water molds based on their filamentous growth and the presence of coenocytic hyphae (multinucleate)
- Cell walls are made of cellulose, not chitin as in fungi
- Phytophthora inestans causes the late blight disease in potatoes and contributed to the Irish potato famine
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What is Golden algae?
- Also called chyrophytes
- Most are unicellular, some are colonial
- Golden algae are named because of their golden-brown color
- Chloroplast pigments dominated by the carotenoid fucoxanthin
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What are diatoms?
- Unicellular, phototrophic
- Over 100,000 species of diatoms
- Contain frustules
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Where do diatoms live?
Freshwater and marine habitats
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What are frustules?
- Cell walls made of silica with proteins and polysaccharides attached to it
- Protect against predation
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When did diatoms appear on earth?
200 million years ago
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How are cercozoans and Radiolarians distinguished from toher protists?
By their threadlike pseudopodia
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What are cercozoans?
- Exclusively marine organisms
- They form shell-like structures called tests
- Tests are made from organic materials reinforced with calcium carbonate
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What are tests made from in Cercozoans?
Made from organic materials reinforced with calcium carbonate
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What are Radiolarians?
- Mostly marine, heterotrophic organisms
- Tests are made of silica
- Name is derived from radial symmetry of tests
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What are tests made from in Radiolarians?
Silica
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What is an Amoebozoa?
- terrestrial and acquatic protists that use pseudopodia for movement and feeding (phagocytosis of bacteria and smaller protists)
- Move by amoeboid movement (cytoplasmic streaming)
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What are the major groups of amoibozoa?
- Gymnamoebas
- Entamoebas
- Slime molds
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What are Gymnamoebas?
Free-living, inhabit soil and acquatic environements
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What are Enamoebas?
Parasites of vertabrates and invertabrates
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What is slime mold?
- Previously grouped with fungi because they have similar life cycle: produce fruiting bodies with spore for dispersal
- Motile, can move across surfaces rapidly
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What are plasmoidal slime molds?
- Have vegtetative forms that are masses of protoplasm of indefinite size and shape that contain multiple nuclei
- From the plasmodium, a sporangium can form, cotnaining multiple haploid spores
- The spores germinates, yielding a flagellated swarm cells. The fusion of two swarm cels regenerates the diploid plasmodium
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What is the result of the fusion of two swarm cells?
The fusion of two swarm cells regeerates the diploid plasmodium
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What is cellular slime mold?
Vegetative forms composed of single amoebae
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How do cellular slime molds move?
Aggregate as a pseudoplasmodiu (slug) that can move as a single unit
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How does cellular slime mold form new amoebae?
May form diploid amcrocysts, undergo meiosis to form new aboebae
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