lecture 7 - Prokaryotes, Eukaryotes, and Multicellularity...

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Prokaryotes, Eukaryotes, and Multicellularity What are bacteria and Archaea Importance Antibiotic resistance Eukaryot evolution Evolution of multicellularity http://www.stephenjaygould.org/library/gould_bacteria.html Figure 26.2 Figure 26.2 rRNA phylogeny of the tree of life Prokaryotes vs. Eukaryotes no (m-e) nucleus membrane-enclosed nucleus circular DNA chromosomes no (m-e) organelles mitochondria, chloroplasts, golgi, endoplasmic reticulum 70s ribosomes 80s ribosomes binary fission mitosis conjugation, trans- formation, transduction meiosis cell wall cellulose membrane when present Binary Fission – asexual reproduction Prokaryotes are important Earth contains more bacterial organisms than all others combined Prokaryotes live in more places and show greater diversity in metabolism than any other group
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Its estimated that total bacterial biomass may exceed all the rest of life combined. Prokaryotes alone constitute the first half of life's history Prokaryotes are important Bacteria have been found at a depth up to 4 miles into the earth !0% of our (human) mass is bacteria with more bacterial cells than human cells Bacteria account for many human diseases Prokaryote Biology Most prokaryotes are cocci, bacilli, or spiral forms. Some link together to form associations, but very few are truly multicellular. Prokaryotes reproduce asexually by fission, but also can exchange genetic information. Bacteria An important source of disease Most bacteria are not pathogenic – beneficially crowd out pathogens Important in ecology - decomposers / degraders nitrogen fixation cellulose breakdown photosynthesis Figure 26.7 Bacterial cell wall
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The Archaea Archaea cell walls lack peptidoglycan, and their membrane lipids contain branched long-chain hydrocarbons connected to glycerol by ether linkages. The Bacteria Firmicutes are diverse; some produce endospores, resting structures resistant to harsh conditions. Actinomycetes
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This note was uploaded on 02/19/2011 for the course BSCI 106 taught by Professor Porter during the Spring '08 term at Maryland.

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lecture 7 - Prokaryotes, Eukaryotes, and Multicellularity...

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