BIO 326R 1st Edition Lecture 26 Outline of Last Lecture I. Siderophoresa. IronII. Heterocystsa. Cyanobacteriab. Endosymbiotic theoryIII. Biofilmsa. Polymeric matrixb. Dnase treatmentIV. Archaeaa. Bacteria vs. archaea vs. eukaryaOutline of Current Lecture I. Archaea—Methanogensa. MethanogenesisII. Motilitya. Swimmingi. Chemotaxisii. Biased random walkingb. Twitchingi. Fimbriae vs. pilliii. Glidingiii. swarmingCurrent LectureArchaea—Methanogens- late 1700s—Voltao experimented in marshes and swampso showed that archaea make combustible gas (methane—CH4)- methanogenesis reactiono CO2 (reduced—electron acceptor)+ H2 (oxidized—electron donor CH4 + 2H2OThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Or, CH3COOH CH4 + CO2 Requires anaerobic conditions- Use methane as a source of natural gaso Clean burning gas- But 20 times worse than CO2 as a greenhouse gas- Methanogenesis reactions occur:o In sewage systems, waste water treatmento Rumen of cattleo Human gut ~50% have methanogenso Gut of termites- Mostly mesophiles, some extremophiles- Interested in methanogenesis for renewable energyMotility- ~20% are motile- Benefit is to move to a more hospitable environment- Observe motility by looking under microscope- Brownian Motiono Movement caused by bacterium being bombarded with water moleculeso Directed movement against currents- Swimming motilityo Utilizes a flagellum Helical filaments composed of protein—up to 10 microns long (longer than bacterium), propeller-like (spins helix to move)o Counter clockwise movement= forward motion Called a runo Clockwise movement= no movement Called a tumbleo Collectively, runs and rumbles allow biased random walk Random= end up where you started, no particular destination Random biased= happens with increase in nutrients, presence of a negative stimuli, etc.—some random movement in order to tumble and reorient, but biased to a particular destination- Chemotaxis= nutrient directed movement- Taxis= movement Each direction change= a tumble occurs- Allows to reorient themselves, happens randomly Biased random walk runs are longer towards the nutrient or end destination, and short when traveling in the opposite/wrong direction Tumbles increase with unfavorable stimuli- Biased random walk can also function to move from harmful conditionso How do we pay for turning the flagella? Proton motive force-- ~1000 protons per turn of flagella Some bacteria use Na+ gradient (ocean bacteria)o Speed Cheetah= 110 km/hr, ~25 body lengths per second Bacteria= 50-60 body lengths per secondo Shape Rods and spiral typically have motility- Their shape lends itself to motility- Spirals spirochetes= flagella inside the cell body VERY few motile cocci—shape is unfavorable for motility- Twitchingo Fimbriae= not used in motility, adheres to hosto Pilli= type IV used in motility and conjugation Pilli are thrown out (like grappling hook) and retract to allow movement More on surfaces, like epithelial cells Pilli grow from base of bacterium, new subunits (pillin proteins) added at base- As opposed to flagella, which grow from tip- Gliding-
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