He

• Chapter 7: Microbial Physiology and Genetics
• Microbial Physiology


  Study of the vital life processes of organisms
• Microbial Nutritional Requirements


  All living protoplasm contains six major chemical elements: carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur
• Major chemical elements in living protoplasm

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
  • Sulfur
• Materials that organisms are unable to synthesize but are required for building macromolecules and sustaining life are termed essential nutrients
• Categorizing Microorganisms According to Their Energy and Carbon Sources

  1. Phototrophs use light as an energy source

  2. Chemotrophs use inorganic or organic chemicals as an energy source

  3. Chemolithotrophs use inorganic chemicals as an energy source

  4. Chemoorganotrophs use organic chemicals as an energy source
• Terms relating to an organism's carbon source

  • Autotrophs use carbon dioxide (CO2) as their sole source of carbon
  • Heterotrophs use organic compounds other than CO2 as carbon sources
• Terms combining energy and carbon source

  • Photoautotrophs use light as an energy source and CO2 as a carbon source
  • Photoheterotrophs use light as an energy source and organic compounds other than CO2 as a carbon source
  • Chemoautotrophs use chemicals as an energy source and CO2 as a carbon source
  • Chemoheterotrophs use chemicals as an energy source and organic compounds other than CO2 as a carbon source
• Ecology


  Study of the interactions between living organisms and the world around them
• Ecosystem


  Interactions between living organisms and their nonliving environment
• Interrelationships among different nutritional types

  Prime importance in the functioning of the ecosystem
• Metabolism


  All of the chemical reactions that occur in a cell
• Metabolic reactions are enhanced and regulated by enzymes known as metabolic enzymes
• Enzymes

  • Biologic catalysts; proteins that cause or accelerate chemical reactions
• Metabolic reactions

  Enhanced and regulated by enzymes known as metabolic enzymes
• Enzymes

  • Biologic catalysts; proteins that cause or accelerate chemical reactions
• Enzymes


  • Specific, catalyzing only one particular chemical reaction
• Enzymes


  • Exert effect on only one particular substance, known as the substrate
• Enzymes

  • Unique three-dimensional shape enables fitting into the combining site of the substrate like a key fits into a lock
• Enzymes

  • Do not become altered during the chemical reaction they catalyze
• Action of a Specific Enzyme (E1)

  Breaking down a substrate (S1) molecule
• Endoenzymes


  • Enzymes produced within a cell that remain within the cell to catalyze reactions
• Exoenzymes

  • Enzymes produced within a cell and released outside of the cell to catalyze extracellular reactions
• Hydrolases and polymerases


  • Examples of metabolic enzymes
• Factors That Affect the Efficiency of Enzymes

  Optimum pH and temperature range, concentration of enzyme and/or substrate, presence of inhibitors
• Metabolism refers to all chemical reactions within a cell
• Metabolite is any molecule that is a nutrient, an intermediary product, or an end product in a metabolic reaction
• Metabolic reactions

  • Catabolism
  • Anabolism
• Catabolism involves breaking down larger molecules into smaller ones, releasing energy
• Anabolism involves assembling smaller molecules into larger ones, requiring the formation of bonds to store energy
• Energy released during catabolic reactions is used to drive anabolic reactions
• Energy can be temporarily stored in high-energy bonds in special molecules, usually adenosine triphosphate (ATP)
• ATP molecules are the major energy-storing or energy-carrying molecules in a cell
• When ATP is used as an energy source, it is hydrolyzed to adenosine diphosphate (ADP)
• If necessary, ADP can be used as an energy source by hydrolysis to adenosine monophosphate (AMP)
• ATP hydrolysis


  Used as an energy source, hydrolyzed to adenosine diphosphate (ADP)
• ADP hydrolysis

  If necessary, ADP can be used as an energy source by hydrolysis to adenosine monophosphate (AMP)
• Interrelationships between ATP, ADP, and AMP Molecules


  Metabolism
• Energy is required not only for metabolic pathways but also for growth, reproduction, sporulation, and movement of the organism, as well as active transport of substances across membranes
• Some organisms (e.g., marine dinoflagellates) use energy for bioluminescence