Microbial Metabolism

• What do microorganisms require energy for?

  To maintain structural integrity, synthesize components, transport substances, grow, and move.
• What are the energy classes of microorganisms?

  • Chemotrophs
  • Chemoorganotrophs
  • Chemolithotrophs
  • Phototrophs
  • Oxygenic Photosynthesis
  • Anoxygenic Photosynthesis
• What are chemotrophs?


  Organisms that conserve energy from chemicals.
• What is the difference between chemoorganotrophs and chemolithotrophs?

  Chemoorganotrophs use organic chemicals, while chemolithotrophs oxidize inorganic compounds.
• What is Thiomargarita namibiensis classified as?

  A sulfur bacterium.
• How do phototrophs obtain energy?

  They convert light energy into chemical energy.
• What is produced during oxygenic photosynthesis?

  Oxygen (O2).
• What distinguishes anoxygenic photosynthesis from oxygenic photosynthesis?

  Anoxygenic photosynthesis does not yield O2.
• What type of microorganisms are green sulfur bacteria?

  They are anoxygenic photosynthetic bacteria.
• What is the difference between heterotrophs and autotrophs?

  Heterotrophs obtain carbon from organic chemicals, while autotrophs use CO2 as their carbon source.
• What are chemoorganotrophs classified as?

  They are classified as heterotrophs.
• What are the energy sources for different classes of microorganisms?

  Chemicals for chemoorganotrophs and chemolithotrophs; light for phototrophs.
• What role do digestive enzymes play in the body?

  They help in the breakdown of sugar molecules.
• What are catalysts?


  Substances that speed up chemical reactions without being altered.
• What is the function of enzymes?

  Enzymes act as biological catalysts on specific substrates.
• What is lysozyme's function?

  It catalyzes the cleavage of the β-1,4-glycosidic bond in peptidoglycan.
• What are the components of enzymes?

  • Holoenzyme
  • Coenzyme
  • Source
  • Function
• What is thiamine's role in enzymatic activity?

  It is part of the coenzyme cocarboxylase and is involved in the metabolism of pyruvic acid.
• What is riboflavin's function?

  It acts as a coenzyme in flavoproteins and is active in electron transfers.
• What is the role of nicotinic acid in enzymatic activity?

  It is part of the NAD molecule and is active in electron transfers.
• What is pyridoxine's function?

  It acts as a coenzyme in amino acid metabolism.
• What is cyanocobalamine's role in enzymatic activity?

  It is active in amino acid metabolism.
• What factors influence enzymatic activity?

  • Temperature: Reaction rate increases with temperature.
  • pH: Activity declines above or below optimum pH.
  • Substrate Concentration: Maximum activity at high substrate concentration.
• How does temperature affect enzymatic activity?

  The rate of most chemical reactions increases as temperature increases.
• What happens to enzymatic activity when pH is not optimal?

  Activity and reaction rate decline.
• What is the effect of substrate concentration on enzymatic activity?

  Maximum rate of activity can be obtained with high substrate concentration.
• What is the relationship between dental caries and sucrose in bubblegum?

  Sucrose causes a decrease in pH of saliva, eroding tooth enamel and exposing it to decay.
• How is energy released in ATP similar to kerosene?

  Both involve the release of energy during oxidation-reduction reactions.
• What are oxidation-reduction reactions?


  Reactions involving the transfer of electrons from one molecule to another.
• What happens when a molecule loses an electron?

  It is said to be oxidized.
• What happens when a molecule gains an electron?

  It is said to be reduced.
• In photosynthesis, what is oxidized and what is reduced?

  Water is oxidized, and glucose is reduced.
• What are dehydrogenation reactions?

  Biological oxidations that involve the loss of hydrogen atoms.
• How is ATP generated during oxidation-reduction reactions?


  Energy released is trapped by the formation of ATP.
• What is phosphorylation?


  The addition of P to a chemical compound.
• What is glucose's role in carbohydrate catabolism?


  It is the most common carbohydrate energy source used by cells.
• What are the two general processes microorganisms use to produce energy from glucose?

  1. Cellular respiration
  2. Fermentation
• What are the stages of cellular respiration?

  1. Glycolysis
  2. Formation of Acetyl Coenzyme A
  3. Citric Acid Cycle
  4. Electron Transport and Chemiosmosis
• What is the difference between aerobic and anaerobic pathways in cellular respiration?

  Aerobic pathways use oxygen, while anaerobic pathways do not.
• What is the chemical equation for aerobic respiration?

  $C_6H_{12}O_6 +$$6O_2 \rightarrow 6CO_2 +$$12H_2O +$$\text{Energy}$