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226N Exam 2 Review

226N Exam 2 Review - Bacterial Growth Temperature...

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Bacterial Growth Temperature : Psychrophiles (cold) Range: 0-20˚C Optimum: 15˚C Mesophiles (moderate) Range: 25-40˚C Optimum: 37˚C Thermophiles (heat) Range: 45-100˚C Optimum: 60˚C - minimum temperature: very slow growth - optimum temperature: fastest growth - max temperature: growth is still possible, but slow pH : - pH = - log[H+] - buffer: compound that helps keep the pH from changing drastically - ex: NaH 2 PO 4 Osmotic pressure : pressure required to prevent movement of water into a solution - isotonic: overall concentration of solutes are equal - hypotonic: lower conc. of solutes inside the cell (cell swells) o solution has more water - hypertonic: higher conc. of solutes inside the cell Oxygen : - aerobic : oxygenic terminal as electron acceptor ex: - anaerobic : do not use O 2 - obligate aerobes : require O 2 to live ex: Pseudomonas aeruginosa - microaerophilic : aerobic, but do not require O 2 ex: N. gonnorrheae - facultative anaerobe: grow w/ or w/o O 2 ex: E. coli (better w/ O 2) - aerotolerant anaerobe: grow equally well w/ or w/o O 2 ex: Enterococcus fecalis - obligate anaerobe: cannot grow in O 2 ex: Clostridium tetani Growth cycle : - N = N 0 2 n – usually measure cells/unit volume o N: Number of bacteria after n generations o N 0 : initial number of bacteria - n = t/g – number of generations and generation time o n: number of generations o t: time in hours o g: generation time in hours/generation Growth curve : - lag phase: little or no cell division; adapting to environment - exponential phase: cells begin to divide and enter a period of growth - stationary phase: metabolic activities begin to slow; equilibrium - death: number of deaths eventually exceeds the number of new cells formed - Bacterial Genetics Definitions: - chromosome : structures containing DNA that physically carry hereditary info - gene : segments of DNA that code for functional products - site : nucleotide sequence w/o functional unit but where proteins can recognize and bind to - replication : 1 “parental” dsDNA molecule is converted to 2 identical “daughter” molecules - transcription : DNA mRNA
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- translation : protein synthesis :: mRNA proteins - transformation : genes are transferred from one bacterium to another as “naked” DNA - conjugation : requires direct cell contact; cells must be of opposite mating type - transduction : bacterial DNA transferred from a donor cell to a recipient cell inside a virus - recombination : exchange of genes b/w two DNA molecules to form new combinations of genes on a chromosome - plasmid : self-replicating, gene-containing circular piece of DNA about 1-5% the size of the bacterial chromosome - recombinant DNA : recipient cell that incorporates donor DNA into its own DNA - mRNA : carries coded info for making proteins from DNA to the ribosomes - tRNA : recognize specific codons and transport the required amino acids
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226N Exam 2 Review - Bacterial Growth Temperature...

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