BIO 326R 1st Edition Lecture 27 Outline of Last Lecture I. Archaea—Methanogensa. MethanogenesisII. Motilitya. Swimmingi. Chemotaxisii. Biased random walkingb. Twitchingi. Fimbriae vs. pilliii. Glidingiii. swarmingOutline of Current Lecture I. Motility continueda. Swimming, Twitching, Swarming, Glidingb. Memoryc. TaxisII. Stressa. Recognition and gene expressionb. RpoSCurrent LectureMotility- Swimming—flagella- Twitching—pili- Swarming—movement on a wet surface using flagellao Differentiates many flagella when senses wet surfaceso Slim later—polysaccharide capsule- Gliding—myxococcuso Not a single mechanismThese 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 Uses a surfaceo Generally slower than swimmingo Pili can be required, but not allo Possible mechanism is ejection of polysaccharide from one end of the bacteria toserve as momentum for movement- Bacteria net movement away from low nutrients (tumble) and toward high nutrients (long run)o Recognizes with memory Continually compares the concentration of a nutrient now to what their memory is from a previous concentration Complicated—involves receptors, methylation, a phosphorylation of proteins Accommodation—bacterium resets its memory to an attractant- Higher concentration of an attraction to stimulate long runs- Taxis (bacteria can have more than one)o Chemotaxis= chemical signals (ex: glucose)o Phototaxis= light signalso pH taxis= pH change signalso aerotaxis= oxygen signals (aerobic respiration)o magnetotaxis= sense the Earth’s magnetic field good for experiments—can use a magnet to easily isolate these bacteriao thermotaxis= temperature change signals - flagella and pili motility; flagella, pili, fimbriaerecognize various taxis signalsStress- defined by a change- recognize stress adapt to stress by altering gene expression for survival during stresso specific or general- stress forms are context (bacterium) dependento certain changes cause stress in certain bacteriao antibiotics, O2 changes, starvation, temperature changes, pH changes, osmotic- bacteria create their own stresso starvationo waste, fermentation products (lactic acid—pH change)- response to stress and altering gene expressiono transcriptional regulatory proteinso sigma factors RpoS—stationary phase sigma factor- Tells RNAP where to go and is required for survival under stresses in E. coli- General response o Recognizes different promoter sequences compared to sigma 7po Promoters are upstream of genes that encode proteins important for stress
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