Lecture 11: Taxonomy of Eukaryotes Flashcards
How do you determine phylogeny for eukaryotes?
MLST&18s genes sequencing
True or False. The relationship between 18s rRNA genes is weaker for eukaryotes than 16s RNA for prokaryotes.
True
Primary endosymbiosis refers to what?
Cell engulfs bacteria->become mitochondrion/chloroplast
Cell form cyanobacteria lineage of bacteria engulfed too
Secondary endosymbiosis refers to what?
Cyanobacterial cells diverge to separate lineages
Red algae-> turns into chloroplast (Dinoflagellates/Apicomplexans)
Green algae->turns into chloroplast
(Euglenids/chlorarachniophytes)
What are green algae? (Chlorophytes)
- Closely related to plants, mostly inhabit freshwater
- can be unicellular or multicellular
- can reproduce sexually/asexually
- endolithic algae grow inside porous rocks
What are red algae? (Rhodophytes)
- Mostly marine, some freshwater/terrestrial
- Mostly multicellular, can be unicellular
- Unicellular->Galdieria
What gives red algae their colour?
Phycoerythrin->accessory pigment
More created by cells @ greater depth
Describe the role of red and green algae in secondary endosymbiosis.
Are the precursors of chloroplasts
What is a diplomonad? (Girardia)
Eukaryote with 2 nuclei of equal size
Have mitosomes
Lacks ETC and TCA enzymes
What is a parabasalid? (trichomonas)
Eukaryote without mitochondria
Have hydrogenosomes (anaerobic metabolism)
contain parabasal body (supports golgi)
What do diplomonad and parabasalids have in common?
Both unicellular eukaryotes, flagellated, no chloroplasts, live in anoxic environments
What are amitochondriate eukaryotes?
Eukaryotes without mitochondria. Contain mitosomes of hydrogenosomes instead.
What is a mitosome?
Derived from mitochondria, reduced form
No TCA enzymes/ respiratory chain
Involved in maturation of FeS clusters
What is a Hydrogenosome?
Present in eukaryotes whose metabolism is strictly fermentative
Oxidizes pyruvate to H2, Co2 and acetate
Sometimes H2 consuming archaea also present (Methanogens)->primary endosymbiosis
What is a cyst?
Specialized structure, more protists differentiate into cysts (encysted)
Protect cells from environment
Survive long periods of starvation/dessication
Survive infection by prokaryotes
How does Girardia lamblia cause Giardiasis? (Diplomonad)
- Food/water is contaminated
- Cysts go to trophozoite form in intestine, multiply and go back to cyst form
- Cysts and trophozoites passed in stool, only cysts survive
How does trichomonas Vaginalis cause an STI? (Parabasalid)
- Doesn’t survive well outside (doesn’t form cysts)
- Transported through body fluids
What are euglenozoans?
Unicellular flagellated eukaryotes
What is a kinetoplastid? (Euglenozoan)
- Contain kinetoplast (mass of DNA in single mitochondrion)
- Live in aquatic environments, feed on bact.
What does Trypansoma brucei cause? (Kinetoplastid)
African sleeping sickness (carried by tsetse fly)
What is a Euglenid?
- Flagellate, non pathogenic and phototrophic
- contains chloroplasts
- can also feed on bact., lose chloroplast if lives in the dark
What is an aveloate?
- Protist, contain alveoli (sacs under cytoplasmic membrane)
- May function to help cells maintain osmotic balance
- contractile vesicle in paramecium
What is a ciliate?
- Posses cilia at some stage of their life
- Use cilia for motility and to obtain food
- have two nuclei (macro and micronuclei)
What are Dinoflagellates?
Marine/freshwater phototrophic organisms
What are apicomplexans?
Obligate parasites of animals
Complex life cycle
1. Sporozoite-> cell that infects new hosts
2. Gametocyte-> gamete forming cells
Contain apicoplasts
Can cause malaria (Plasmodium falciparum)
What is an apicoplast?
Degenerated chloroplasts
Lack pigments and phototrophic activity, but still carry many anabolic pathways
What is a stramenophile?
Chemoheterotrophs
Have flagella with many short hairlike extensions
Includes oomycetes, diatoms, golden algae, brown algae
What are oomycetes? (stramenophile)
Also called H2O molds
Filamentous growth, presence of coenocytic (multinucleate) hyphae=no cell division
Cell walls made of cellulose
(P. infestans=potato famine)
What is golden algae? (stramenophile)
Phototrophs, also called chrysophytes
Mostly unicellular, some are colonial (form groups)
Chloroplast pigments dominated by carotenoid fucoxanthin
What are diatoms?
Unicellular/phototrophic
Freshwater/marine habitats
Contain fustules
What is a fustule?
Cell walls made of silica, proteins, polysacchs. Protect against predation.
What are cercozoans?
Exclusively marine organisms, unicellular protist
Form ornate shell like structures (tests)
Tests made from organic materials reinforced with calcium carbonate
What are radiolarians?
Mostly marine, heterotrophic
Test made of silica
What are some similarities between cercozoans and radiolarians?
Both unicellular, distinguished from other protists by pseudopodia
What are amoebozoa?
Terrestrial and aquatic protists
Use pseudopodia
Phagocytosis of bact and smaller protists
move by cytoplasmic streaming
What are the main groups of amoebozoa?
Gymnamoebas, entamoebas, slime molds
What are gymnamoebas?
Free living amoeba, inhabit soil and aquatic environments
What are entamoebas?
Parasites of vertebrates and invertebrates
What are plasmodial slime molds?
several kinds of unrelated eukaryotic organisms that can live freely as single cells, but can aggregate together
What is the life cycle of a plasmodial slime mold?
Have vegetative forms-> masses of protoplasm
Indefinite shape and size (plasmodium)
Multiple nuclei
1. Sporangium can form, containing multiple haploid spores
2. Spores germinate=swarmer cell
3. 2 swarmer cells can join=diploid plasmodium
What are cellular slime molds?
Vegetative forms compose of single amoebae (haploid)
Aggregate of multiple amoeboid cells=pseudoplasmodium (slug)-cells do not fuse
Whats the difference between cellular and plasmodial slime molds?
Cellular=1 cell aggregated
Plasmodial=mass of protoplasm
How do cellular slime molds reproduce?
When fruiting body formed, cells differentiate into spores
May undergo sexual reproduction to form diploid macrocysts+meiosis
True or false. Slime molds are capable of primitive agriculture.
true
True or false. Fungi are multicellular.
True
True or false. Slime molds are capable of primitive agriculture.
True
What are the two different kinds of hypha fungi can have?
Cyoenocytic
Separate
Whats the difference between coenocytic and separate hyphae?
Coenocytic: Cytoplasm and nuclei not subdivided into cells
Separate: Nuclei separated by cross wall
What are fungal walls made of?
Chitin
How do fungi feed?
Secrete extracellular enzymes that digest complex organic materials
How do fungi create asexual spores?
Hyphae that extend above surface produce asexual spores (conidia)-pigmented, resistant to drying
What is a conidiophore?
Specialized reproductive hyphae
How do fungi form symbiotic association with plant roots?
Some species of fungi (Mycorrhizae) form close relationships with plant roots =glomeromycetes
Mycorrhizae help plant roots obtain P, in turn fungi obtain nutrients from plant
What are ectomycorrhizae?
Bacteria that form a sheath around plant root-doesn’t penetrate fungal hyphae embedded in plant root
How do fungi cause disease?
Form specialized hyphae (haustoria) to penetrate plant cells, consume cytoplasm
What is mycoses?
fungal infection of animals
How do fungi reproduce asexually?
- Grow and spread hyphal filaments
- Asexual reproduction of spores
- Simple cell division (budding)
How do fungi reproduce sexually?
Form sexual spores from fusion of two haploid cells then undergoes meiosis
How does S. cerevisae reproduce?
- Bud into haploid cells
- Form two different sexed cells (a and alpha) which undergo cell fusion
- Fused cell undergoes nuclear fusion and meiosis =ascus
- Creates new haploid ascospores
What is an ascospore?
Sexual fungal cells (s. cerevisae)
What are the three different kinds of fungal spores?
Ascospores, basidospores, zygospores.
What is lichen?
Association between fungi and algae/cyanobacteria
