chap 7

• Physiology


  The study of the vital life processes of organisms
• Microbial physiology concerns the vital life processes of microorganisms
• Six major chemical elements in living protoplasm

  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Phosphorus
  • Sulfur
• Essential nutrients


  Materials that organisms are unable to synthesize, but are required for building macromolecules and sustaining life
• Terms relating to an organism's energy source

  • Phototrophs
  • Chemotrophs
  • Chemolithotrophs
  • Chemoorganotrophs
• Terms relating to an organism's carbon source

  • Autotrophs
  • Heterotrophs
• Terms combining energy and carbon source

  • Photoautotrophs
  • Photoheterotrophs
  • Chemoautotrophs
  • Chemoheterotrophs
• Ecology


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


  The interactions between living organisms and their nonliving environment
• Interrelationships among the different nutritional types are of prime importance in the functioning of the ecosystem
• Metabolism


  All of the chemical reactions that occur in a cell
• Metabolic enzymes


  Enzymes that enhance and regulate metabolic reactions
• Biologic catalysts


  Enzymes are proteins that either cause a particular chemical reaction to occur or accelerate it

  
• Enzymes

  • They are specific, catalyzing only one particular chemical reaction
  • They fit the combining site of the substrate like a key fits into a lock
  • They do not become altered during the chemical reaction they catalyze

  
• Endoenzymes


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

  
• Exoenzymes


  Enzymes produced within a cell and then released outside of the cell to catalyze extracellular reactions
• Examples of metabolic enzymes

  • Hydrolases
  • Polymerases

  
• Factors affecting enzyme efficiency

  • Optimum pH range
  • Optimum temperature range
  • Optimum concentration of enzyme and/or substrate
  • Presence of inhibitors
• Metabolite


  Any molecule that is a nutrient, an intermediary product, or an end product in a metabolic reaction
• Catabolism


  All catabolic reactions in a cell
• Anabolism


  All anabolic reactions in a cell
• Catabolic reactions


  Involve the breaking down of larger molecules into smaller ones, releasing energy
• Anabolic reactions


  Involve the assembly of smaller molecules into larger molecules, requiring the formation of bonds and storing energy
• ATP

  The major energy-storing or energy-carrying molecule 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)
• Energy is required for metabolic pathways, growth, reproduction, sporulation, movement, and active transport of substances across membranes
• Cellular mechanisms that release small amounts of energy as the cell needs it usually involve a sequence of catabolic and anabolic reactions
• Biochemical pathway


  A series of linked biochemical reactions occurring in a stepwise manner, from a starting material to an end product
• Glucose can be catabolized by aerobic respiration and fermentation
• Aerobic respiration of glucose

  1. Glycolysis

  2. The Krebs cycle

  3. The electron transport chain
• The Krebs cycle is a biochemical pathway consisting of eight separate reactions, each controlled by a different enzyme
• In eukaryotes, the TCA cycle and the electron transport chain occur in mitochondria
• In prokaryotes, the TCA cycle and the electron transport chain occur at the inner surface of the cell membrane
• Glycolysis


  1. 9-step biochemical pathway

  2. Each step requires a specific enzyme

  
• Glycolysis


  First step in the aerobic respiration of glucose
• Krebs cycle


  1. Biochemical pathway consisting of 8 separate reactions

  2. Each controlled by a different enzyme

  3. Only 2 ATP molecules produced

  4. Number of products (NADH, H+, FADH2) formed, which enter the electron transport chain
• Electron transport chain


  1. Series of oxidation-reduction reactions

  2. Energy released as electrons transferred from one compound to another

  3. Many enzymes involved, including cytochrome oxidase

  4. Large number of ATP molecules produced by oxidative phosphorylation
• Aerobic respiration is very efficient
• Fermentation reactions do not involve oxygen, take place in anaerobic environments