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Phylogeny and Protists

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Biology (Sci)
BIOL 111
Irene Gregory- Eaves

13/09/11 Phylogeny: 1.7 million species Taxonomy: - binomial nomenclature: Genus species, or Genus species - Carolus Linnaeus (1758) Then: Kingdom, phylum, class, order, family, genus, species Now: 3 domians – Bacteria, Archaea, Eukarya Reading Phylogenies: Root: common ancestor Node: where branches are started, order around node has no significance Clade: ancestor and all its decendants Sister group: closely related pairs of taxa (generally species) with recent common ancestors Outgroup: closely related taxon outside of the group of interest (clade) - At the end of a tree: species, populations, genetics - alleles Homology: similarity due to common ancestor (eg. bat wing/human arm) Analogy: similarity arose through different, independent events (eg. wings of bird/insect) (eg. bat/bird wings – bones evolved homologously, wings themselves analagous) = Convergent evolution Building a phylogeny: 1. list traits/characters for taxons 2. identify order of progression of traits only looking at homologous traits 3. let computer find groupings trying to find monophyletic groupings a. monophyletic group = ancestor + all descendents b. paraphyletic group = missing descendent c. polyphyletic group = more than one chain involved (things don’t belong) Derived trait: distinguishing trait shared by a group that was not found in their ancestor Origin of eukaryotes: Eu – True Karyon – Kernal (nucleus) - formation of O2 preceded eukaryotes - differ from prokaryotes: membrane bound organelles (eg. mitochondria, nucleus, chloroplast), larger ribosomes (80s) 1. loss of cell wall 2. infolding of membrane = increased surface area 3. pinching of membrane = vacuoles  with DNA/ribosomes attached form nucleus, further infolding form endoplasmic reticulum 13/09/11 4. building of cytoskeleton 5. extension of cytoskeleton = flagellum for motion 6. development of phagocytosis 7. swallow proteobacteria  mitchodria 8. swallow cyanobacteria  chloroplast Endosymbiosis: internal & living together (eg. Mitochodira) - one cell swallows another and lives inside without being digested - over long time living together  genome of endosymbiote reduces or may move to the nuclear genome - Evidence: - double membrane - reproduce with binary fission, like bacteria - bacterial genes found in mitochondria Diversity of Protists: - Eukaryotes: monophyletic, are not just plants, fungi, and animals - Protists: not a taxanomic group, used to describes eukaryotes that do not fit into other defined taxa Size: microscopic  meters longs Trophy: photoautotrophs and (chemo)heterotrophs Niches: free-living, endosymbiotes, parasites Diverse methods of locomotion 1. Unikonts: single cone - refers to optional single flagella - Close to root of eukaryotic tree a) Amoebas (loboseans): unicellular - move with pseudopods, extensions of cytoplasm - may have a “test” = shell - nom with phagocytosis - some are pathenogenic = amoebic dysentery b) Slime molds: like amoebas - move by cytoplastic streaming - eat by phagocytosis - form large aggregate = slug - create fruiting structures with spores for reproduction c) Choanoflagellates = collar - sister group to animals - colonial - use flagella to capture prey 2. Rhizaria: Typically have long thins pseudopods a) Foraminiferans: - Marine primarily
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