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Unformatted text preview: today’s factoid • A study published in 2009 funded by the Na8onal Science Founda8on found that the rate at which some important ﬁsh species have been exploited has been decreasing in some areas around the world. The study was mostly in developed na8ons with well studied ﬁsheries. But some ﬁsheries in developing na8ons provided posi8ve results e.g. Kenya, local eﬀorts at regula8on have led to larger average ﬁsh size and increases in incomes of ﬁshers hIp://www.nsf.gov/news/news_summ.jsp? cntn_id=115279&govDel=USNSF_51 see 'NSF Fisheries Study' in Biology in the News folder on Blackboard Produc8on data from UN Food and Agriculture Organiza8on hIp://www.fao.org/docrep/003/x8002e/x8002e07.jpg • • • • • Major Prokaryote groups • Low‐GC Gram posi.ve bacteria (not all are Gram posi.ve) • Some produce highly environmentally resistant endospores, to survive harsh environments • Can survive for 1000s of years, perhaps longer • This group includes Bacillus anthracis (anthrax), Clostridium botulinum (botulism), Staphylococcus, Streptococcus • Also includes Micoplasma, smallest known cellular organism (.2 µm) Major Prokaryote groups Agrobacterium tumifaciens is a Proteobacteria injects its DNA to transform plant cells a“gene.c engineer” of the bacterial world Crown gall disease caused by Agrobacterium • Proteobacteria • Largest bacterial group, also called “purple bacteria” • Huge diversity, especially in metabolism • Ancestor of the eukaryo8c mitochondria was a Proteobacteria • Includes some nitrogen‐ﬁxers, e.g. Rhizobium • Includes Escherichia coli • Diseases: Yersinia pes<s (bubonic plague), Vibrio cholerae (cholera), Salmonella typhimurium Major Prokaryote groups • ARCHAEA • Much less is known than in Bacteria • Known for extreme environments, but many in less extreme environments • Some have diﬀerent lipid membrane cons8tuents than bacteria, eukaryotes Major Prokaryote groups • Crenarchaeota • Known for living in very hot and/or very acidic environments • Sulfolobus live in hot sulfur springs (70‐75˚C; pH 2‐3) Major Prokaryote groups Commercial sea salt evapora.ng ponds • Euryarchaeota • Some produce methane (methanogens); obligate anaerobes • In the guts of caIle and other mammals • Important source of atmospheric methane; greenhouse eﬀect • Also known for some extreme environments • e.g. extreme halophiles (very salty environments) • Reddish due to carotenoid pigments • Can withstand highly alkaloid environments (pH ~11) Prokaryotes provide vast and diverse beneﬁts to all life on Earth • • • • • Decomposi8on (along with Fungi) Nitrogen cycling Cyanobacteria in ancient Earth ‐> O2 Gut symbionts in animals; aid in diges8on and produce vital compounds, e.g. vitamin B12 Some are pathogenic (minority) – Human prokaroy8c pathogens are all Bacteria (not Archaea) – Some produce endotoxins (generally gram nega8ve bacteria) ‐ released when cells lyse • Usually lipopolysaccharides • Cause various disease symptoms but are usually not fatal – e.g. Salmonella – Some produce exotoxins, highly toxic • Usually proteins • e.g. Clostridium (tetanus, botulism), Vibrio (cholera), Yersinia (plague), Bacillus anthracis (anthrax) Our prokaryote friends • Aid in manufacturing food products – Along with yeasts (fungi) Our prokaryote friends • Aid in waste water treatment Our prokaryote friends • Gene8c engineering and an8bio8cs – Restric8on endonucleases – Plasmids – Agrobacterium transforma8on of crop plants hIp://cndls.georgetown.edu/ applica8ons/posterTool/data/users/ cartoon044.jpg Origin and diversity of eukaryotes (Domain Eukarya) • How did they evolve? • Diversity, especially microbial eukaryotes – Many unicellular forms – Great reproduc8ve diversity – Many parasites, important diseases Eukarya Archaea • Impossible to memorize all of Ch. 27 – Concentrate on content of this lecture but go through the ques8ons in the book / electronic resources Bacteria Two terms that are no longer in favor • Pro8sts ‐ “eukaryotes that are neither land plants, animals, nor fungi” • Protozoans ‐ microbial eukaryotes that used to be classiﬁed as single‐celled “animals” • Modern phylogene8c systema8cs view indicates that these are non‐monophyle.c groups – you will ﬁnd out much more about monophyle8c groups later in the semester – a monophyle8c group contains a single ancestor and all of its descendants Eukaryotes • Loss of cell wall • • • • Diges8ve vesicles More complex ﬂagella structure Nuclei Organelles – Chloroplasts • A few have lost mitochondria – Infolding of plasma membrane to increase surface area without increasing volume All of these innova8ons happened on this lineage > 1 billion years ago Eukarya – Almost all eukaryotes have mitochondria > 2 bya > 3 bya Archaea • Evolved mul8ple 8mes • Primary, secondary (and even more complex) events Bacteria Loss of cell wall • Infolding of plasma membrane to increase surface area without increasing volume • Enables evolu8on of membrane‐bound structures inside the cell One possible sequence of eukaryote evolu8on Loss of cell wall infolding Internal membranes studded with ribosomes Cytoskeleton evolves (microﬁlaments, microtubules) DNA becomes aIached to a membrane vesicle; precursor to the nucleus Flagellum evolves using cytoskeletal elements; propulsion is possible Diges8ve vacuoles Endosymbio8c event gives rise to mitochondria Endosymbio8c event gives rise to chloroplasts Chloroplasts ‐ mul8ple origins Only glaudophytes retained pep8doglycan The key clue is the number of membranes surrounding the chloroplast 2 = primary 4 = secondary Some lineages have undergone two diﬀerent events; have two types of chloroplasts (ter8ary, quaternary may have also occurred) Endosymbio8c theory hIp://en.wikipedia.org/wiki/Image:Merezhkovsky_K_S.jpg • Mitochondria evolved from ancient bacteria • Chloroplasts evolved from ancient photosynthe8c bacteria or photosynthe8c eukaryotes • Originated by Konstan8n Mereschkowski in 1905 • Revived and inves8gated by Lynn Margulis in the 1960s‐1970s • Was once thought to be a strange idea • Ini8al evidence was structural • DNA evidence sealed it hIp://en.wikipedia.org/wiki/Image:Lynn_Margulis.jpg hIp://porpax.bio.miami.edu/~cmallery/255/255hist/mcb1.15.cytoskeleton.jpg cytoskeleton • Important for: – Mo8lity • Pseudopodia, cilia, ﬂagella hIp://ﬁg.cox.miami.edu/~cmallery/150/life/meiosis.pics.jpg – Chromosome movement during mitosis and meiosis Cytoskeleton components have been discovered in the thermophilic bacteria Thermotoga mari<ma • eukaryo8c cytoskeleton is made of ac8n and tubulin protein monomers which polymerize into ﬁlaments • T. mari<ma has homologs of both proteins which are also capable of polymerizing into cytoskeletal structures – important for cell shape in this species • van den Ent, F., Amos, L.A., and Lowe, J. 2001 Prokaryo8c origin of the ac8n cytoskeleton. Nature 413: 39‐44. • Thanks to Peter Balacky for ﬁnding this report bar is one micron (µm; 1 millionth of a meter) hIp:// www.genomenewsnetwork.org /gnn_images/news_content/ 02_02/extremo_art/art2.jpg ...
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- Spring '08