MICR 2123 Study Guide - Midterm Guide: Rhizobia, Arbuscular Mycorrhiza, Brine Pool
30 Oct 2016
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Document Summary
A group of species that share a common ancestor clade. How does divergence occur between different clades over time: random mutations, natural selection, reductive (degenerative) evolution. The most widely used gene in constructing phylogenetic trees is the gene encoding the small subunit rrna (ssu rrna) The three fundamental domains of life: bacteria, archaea, and eukarya. Bacteria resemble eukaryotes and differ from archaea in these. Taxonomy is the description of distinct life-forms and their organization into different categories: generates a hierarchy of taxa phylum largest, species smallest. Horizontal gene transfer: unrelated species, a piece of dna passes, on plasmid or phage, meet conditional needs, examples: metabolism, pathogenesis, stress response. Vertical gene transfer: parent and offspring, whole genome passes, during replication and cell division. Extreme case of reductive evolution: mitochondria evolved from an alpha-proteobacterium genes still encoded on mitochondria are respiratory genes, chloroplasts evolved from cyanobacteria genes still encoded on chloroplasts are photosynthesis genes.
