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Unformatted text preview: ?mated 3x1028 bacteria and archaea cells in the ocean • There are more bacteria in a single human intes?nal tract than all the humans who have ever existed • Found in just about all imaginable environments – Many extreme environments • Most are unicellular (but some mul?cellular 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] An?bio?cs like penicillin and ampicillin interfere with pep?doglycan synthesis Bacterial cell well components are good targets for an?bio?cs. (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 • Reproduc?on is asexual • But many species can – Binary ﬁssion undergo gene?c recombina?on – e.g. E. coli bacteria use a conjuga?on system – Bacteria can also take up DNA from the environment and some?mes use the sequences as func?onal genes hMp://www.textbookoyacteriology.net/growth.html Metabolic diversity in Prokaryotes • Prokaryotes have had billions more years than eukaryotes to adapt and evolve • Much greater metabolic diversity than eukaryotes LIFE 9th ed Table 26.2 Most bacteria and archaea, all animals, fungi, and many pro1sts are which nutri1onal category? Photosynthe?c bacteria • Photoautotrophs (light = energy source, C02 = carbon source) – Cyanobacteria ‐ use chlorophyll a • Release O2 as byproduct • H20 = “electron donor” • Like eukaryo?c photosynthesis – Others use bacteriochlorophyll • Do not release O2 LIFE 9th ed Fig. 26.9 • Some have H2S as electron donor and release Sulfur instead of O2 • Photoheterotrophs (light = energy source, organic carbon = carbon source) – Purple nonsulfur bacteria hMp://
index.php/Rhodobacter chlorophyll space‐ﬁlling model of chlorophyll a Carbon Hydrogen Oxygen Nitrogen Magnesium hMp://en.wikipedia.org/wiki/File:Chlorophyll‐
a‐3D‐vdW.png chlorophylls work as molecular “antenna” absorb light energy transferring that energy by “resonance energy transfer” to par?cular chlorophyll molecules at “reac?on centers” of chloroplasts reac?on centers transfer electrons to electron transport chain which terminates in the oxida?on (“splizng”) of H2O to yield H+ and O2 photosynthesis • in essence: more later in the course chemolithotrophs • Also called chemoautotrophs • Use inorganic molecules as energy source, e.g. – NH3 or NO2‐(nitrite) ‐> NO3‐ (nitrate) – Or H2, H2S, Sulfur • In the deep see near hydrothermal vents – Communi?es exist with no light – Inorganic molecules such as H2S come from the volcanic vents hMp://www.botos.com/marine/mono3.jpg...
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This note was uploaded on 10/02/2013 for the course BIO 201 taught by Professor True during the Spring '08 term at SUNY Stony Brook.
- Spring '08