Bio 201 S10 Lect 3 (True) v2r

Bio 201 S10 Lect 3 (True) v2r - today’s factoid • ...

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Unformatted text preview: today’s factoid •  •  •  •  •  163 new species found in a recent expedi6on in the Mekong river of southeast Asia the river goes through 16 global ecoregions h?p://www.cnn.com/2009/TECH/ science/09/26/mekong.species/ Story posted in Biology in the News folder on Blackboard one species found was the khorat big‐ mouthed frog, Limnonectes megastomias, which preys on small birds and insects h?p://i2.cdn.turner.com/ cnn/2009/TECH/science/ 09/26/mekong.species/ art.mekong.03.wwf.jpg h?p://chinaview.files.wordpress.com/ 2007/01/mekong‐river‐map‐320x.jpg note •  the original (s6ll posted as of Friday’s lecture) version of this lecture had two slides about the first mid term last fall embedded in it –  please ignore these •  updated version will be posted soon more on extra credit assignment •  TA John Waldron is in charge of this assignment –  see e‐mail and office hours on BB Staff info •  see next slides for Blackboard pages •  How to refer to papers –  in bibliography (“Literature Cited”): •  Helfenstein, F., Losdat, S., Pape Møller , A., Blount, J.D., Richner, H. 2010 Sperm of colourful males are be?er protected against oxida6ve stress. Ecology Le?ers 13: 213–222 –  in text (Helfenstein et al. 2010) •  You will need to provide the correct bibliographic reference in order to get full points •  No revisions will be allowed student version of this page should look different -follow links to submit assignment do not submit .docx files use .doc, .pdf, .rtf, or .txt formats Earliest fossils Eukarya Bacteria Stromatolites ‐ structures formed by cyanobacteria‐like organisms h?p://www.usc.edu/dept/mda/180evolu6on/IMAGES/ Evolu6on of Earth’s ancient ecosystem •  •  •  Marine photosynthe6c bacteria dominated the earth for 1‐2 billion years Before this 6me ‐ no oxygen in atmosphere Massive produc6on of oxygen for a very long 6me –  Oxygenated the oceans –  Oxidized (Fe2+‐>Fe3+) most of the iron on Earth (now mined as iron ore) –  Then, increased percentage of oxygen in atmosphere Enabled the evolu6on of organisms with respiratory metabolism Current composi:on of Earth’s atmosphere •  h?p://en.wikipedia.org/wiki/Earth's_atmosphere#Composi6on Eukaryotes appear in the fossil record 2.3 billion years [email protected] prokaryotes Earliest eukaryote Fossil ~1.2 bya Earliest prokaryote fossil ~3.5 bya The 3 domains of life •  •  •  •  Bacteria Prokaryotes Archaea Eukarya (Eukaryotes) All three have in common: –  Glycolysis h?p://en.wikipedia.org/wiki/Glycolysis –  –  –  –  DNA replica6on mechanism Transcrip6on, transla6on, gene6c code Plasma membranes Ribosomes Differences between Prokaryotes and Eukaryotes •  Prokaryotes do not have cytoskeleton •  Prokaryotes do not divide by mitosis –  They use binary fission •  Prokaryotes do not have a nucleus •  DNA is usually circular •  Prokaryotes do not have membrane‐enclosed organelles (mitochondria, chloroplasts, Golgi apparatus) –  But they can have infoldings of the plasma membrane for various func6ons •  For differences between two domains of Prokaryotes, see table 26.1 –  Don’t have to memorize these When did Prokaryotes originate? •  First fossils •  First fossil evidence of cellular life •  Billions of years to adapt and diversify before Eukaryotes appeared –  But there was already significant diversity –  3.5 billion years ago (bya) >3 bya >2 bya Prokaryote success •  Es6mated 3x1028 bacteria and archaea cells in the ocean •  “The bacteria living in a single human intes6nal tract outnumber all the humans who have ever lived” (Life 8e, p. 563) •  Found in just about all imaginable environments –  Many extreme environments •  Most are unicellular (but some mul6cellular forms known) •  Large diversity, but three most common forms are: cocci, bacilli (rods), and helices Cell wall diversity in Prokaryotes •  Chemically very different from plant, algae, and fungal cell walls •  A major method of classifying bacteria: Gram staining ‐ [purple dye followed by iodine, then alcohol wash and a red counterstain] An6bio6cs like penicillin and ampicillin interfere with pep6oglycan synthesis Bacterial cell well components are good targets for an6bio6cs. (why?) Some other Prokaryote features: movement Salmonella •  Some species use flagella (structurally different from Eukaryote flagella) •  Other species –  Axial filaments •  Spiral movement a spirochaete –  Gas vesicles •  Up and down in water column a cyanobacterium Some other Prokaryote features: sex •  Reproduc6on is asexual •  But many species can –  Binary fission undergo gene6c recombina6on –  e.g. E. coli bacteria use a conjuga6on system –  Bacteria can also take up DNA from the environment and some6mes use the sequences as func6onal genes h?p://www.textbookosacteriology.net/growth.html ...
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This note was uploaded on 02/18/2010 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.

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