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What genes for phylogeny of eukaryotes?
18S rRNA genes for phylogeny of eukaryotes
How are phylogenies constructed?
Phylogenies have been constructed byt aking into account other genes (eg. tubulin, RNA polymerase, and ATPase)
What do amitochondriate eukaryotes have instead of a mitochondria?
Mitosomes and hydrogenosomes
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
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
What is 'encysted'?
Some species of protists are able to differentiate into cysts, becoming encysted
What are cysts similar to?
Cysts are similar to the endospore produced by prokaryotes
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
What are diplomonads and Parabasaids?
- Lacks chloroplasts
- Live on anoic habitats
What are diplomonads?
- Have 2 nuclei of equal size
- Have mitosomes (degenerated mitochondria)
- Key genera: giardia (causes giardiasis)
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
What is Trichomonas vaginalis?
- 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)
What are Euglenozans?
- Unicellular flagellated eukaryotes
- ie Kinetoplastids
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
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
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
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
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)
How do ciliates reproduce?
Two paramecia exchange micronuclei
How many nuclei does a paramecia have?
2: macronucleus and micronucleus
How do ciliates use cilia?
For motility and to obtain food
What are dinoflagellates?
Divers marine and freshwater phototrophic organisms
What is special about dinoflagellates?
- Have two flagella with different insertion points on the cell:
- Transverse flagellum
- Longitudinal flagellum
What are dense suspensions of dinoflagellates called?
How do dinoflagellates poison humans?
- Associated with human poisoning (paralytic shellfish poisoning)
- Accumulation of toxic dinoflagellates in mussels
What is Pfiesteria piscicida?
It is a genus of toxic dinoflagellate responsible for massive fish kills: spores infect fish, germinates, destroy tissue
What do some dinoflagellates secrete?
Some secret neurotoxins
Where do dinoflagellates reach very high numbers?
In warm, polluted water dinoflagellates can reach very high numbers
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)
What are the three stages of amicomplexans life cycle?
- Sporozoite (transmission)
- Gameotoyte (sexual reproduction)
- Other stage
What causes malaria
What causes toxoplamosis?
What causes coccidiosis?
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
What are stramopiles?
- All have flagella with many short hairlike extensions
- Chemoheterotrophs and phototrophic members
- Oomycetes, diatoms, golden algae, and brown algae
What are oomycetes?
- 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
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
What are diatoms?
- Unicellular, phototrophic
- Over 100,000 species of diatoms
- Contain frustules
Where do diatoms live?
Freshwater and marine habitats
What are frustules?
- Cell walls made of silica with proteins and polysaccharides attached to it
- Protect against predation
When did diatoms appear on earth?
200 million years ago
How are cercozoans and Radiolarians distinguished from toher protists?
By their threadlike pseudopodia
What are cercozoans?
- Exclusively marine organisms
- They form shell-like structures called tests
- Tests are made from organic materials reinforced with calcium carbonate
What are tests made from in Cercozoans?
Made from organic materials reinforced with calcium carbonate
What are Radiolarians?
- Mostly marine, heterotrophic organisms
- Tests are made of silica
- Name is derived from radial symmetry of tests
What are tests made from in Radiolarians?
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)
What are the major groups of amoibozoa?
- Slime molds
What are Gymnamoebas?
Free-living, inhabit soil and acquatic environements
What are Enamoebas?
Parasites of vertabrates and invertabrates
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
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
What is the result of the fusion of two swarm cells?
The fusion of two swarm cells regeerates the diploid plasmodium
What is cellular slime mold?
Vegetative forms composed of single amoebae
How do cellular slime molds move?
Aggregate as a pseudoplasmodiu (slug) that can move as a single unit
How does cellular slime mold form new amoebae?
May form diploid amcrocysts, undergo meiosis to form new aboebae