MIC 205 1st Edition Lecture 9 Outline of Last Lecture I. Aerobic respiration cont.II. PhotosynthesisIII. Brief intro to Microbial GrowthOutline of Current Lecture IV. Microbial GrowthV. Nutritional Requirementsa. Energyb. Carbonc. OxygenCurrent Lecture Microbial Growth-Discrete colony, dispersed cells, complex biofilm*Not growth in size—talking about increasing cell number (asexual reproduction)Logarithmic Growth: exponential growth, populations increase to millions in only a few hours (Double the amount every single doubling time)Arithmetic Growth: addition of growth at each roundPhases of Microbial Growth:-lag phase: # of cells remain constant, haven’t started dividing yet-log phase: # of cells increases exponentially-stationary phase: # of new cells = # of cells dying-death phase: more cells dying than being produced, negative slopeNutritional requirements: energy-phototrophs: lightThese 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.-chemotrophs: organic or inorganic chemical productsPhysical requirements: environmental factors-autotrophs: carbon from CO2 (self feeder)-heterotrophs: carbon from other living organismsOxygen requirements: -obligate aerobes-need oxygen-obligate anaerobes-can’t be exposed to airToxic forms of Oxygen:-peroxide anion (hydrogen peroxide): from breaking down lipids, kills cells, (catalase enzyme removes it)-hydroxyl radical: from ionizing radiation and incomplete reduction of hydrogen peroxide (most reactive)-singlet oxygen: rare, generated in photosynthesis-superoxide radicals: common, formed in incomplete reduction of oxygen in aerobic/anaerobic respiration (highly reactive) Oxygen Classifications:- Aerobes- Anaerobes- Facultative anaerobes- Aerotolerant anaerobes- Microaerophiles Nitrogen Fixation:Needed for growth—b/c nucleotide synthesis and amino acid synthesis (which makes DNA and RNA and protein)-acquired from other living organisms, recycled-also need phosphorus, sulfur, and trace
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