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Unformatted text preview: Prokaryotic Domains: Bacteria & Archaea Bacteria, Archaea, and Eukarya: The Three Domains of Life Bacteria Eukarya Archaea Common ancestor of all species living today Introduction to Prokaryotes Only 5000 species of bacteria and Archaea have been named and described; potentially millions exist Bacteria and Archaea live almost everywhere, from below the Earths surface to on Antarctic sea ice Microbiology is the study of microbes, microscopic organisms What is a prokaryote? Basic structure : cell enclosed by: nucleoid contains: lacks a: cytoplasm composed of cytosol & ribosomes Features of prokaryotes cell wall rigid capsule polysaccharide layer ribosomes sites for production of proteins flagella locomotion reproduction: Bacteria and Archaea are haploid and reproduce by fission the splitting of a cell into two daughter cells Bacterial cells can transfer copies of plasmids , extracellular loops of DNA conjugation: plasmid or genes from main bacterial chromosome transferred from one bacteria to another genetic recombination separate from reproduction but some form colonies prokaryotes are usually single cells Bacteria and Archaea: Why Separate Domains? Bacteria cell walls made of: plasma membranes like eukaryotes; glycerol bonded to straight chain fatty acids RNA polymerase: simple, Translation : begins with formylmethionine, different from Archaea and Eukarya Archaea archaea = ancient (incorrect!)archaea = ancient (incorrect!...
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- Fall '10