5a. Microbiology Metabolism Part 2

Catabolic Reactions Overview

  • Focus on finishing metabolic factory processes.

  • Previous processes included:

    • Nutrient intake into the cell.

    • Completion of aerobic and anaerobic respiration.

    • Production of 12 precursor metabolites.

    • Generation of 38 ATP and reducing power.

Fermentation

  • Final catabolic reaction to discuss.

  • Defined as the incomplete breakdown of glucose.

  • Inefficacy of fermentation:

    • Complete glucose breakdown yields 38 ATP.

    • Fermentation only produces 2 ATP per 6-carbon glucose.

Mechanism of Fermentation

  • Fermentation occurs after glycolysis; no electron transport system present.

  • Need for an electron acceptor to transfer electrons from NADH.

  • Breakdown process:

    • Glucose converts to pyruvic acid.

    • Alcoholic Fermentation:

      • Pyruvic acid loses CO2 to form acetaldehyde.

      • NADH transfers electrons to acetaldehyde, producing ethyl alcohol (used in brewing, contributes to bread rising).

    • Lactic Acid Fermentation:

      • Pyruvic acid remains unchanged.

      • NADH transfers electrons to pyruvic acid, producing lactic acid (causes muscle soreness during intense exercise).

Metabolic Factory Reactions Completion

  • Final steps in metabolic reactions:

    • Biosynthesis:

      • Converts precursor metabolites into building blocks (simple sugars, amino acids, nucleic acids, fatty acids, glycerol).

    • Polymerization:

      • Assembles building blocks into more complex structures:

        • Amino acids → proteins.

        • Simple sugars → polysaccharides.

        • Nucleotides → DNA and RNA.

        • Cholesterol and fatty acids → lipids.

    • Assembly:

      • Combines polymers into cellular components (e.g., cell envelope structures).

Cellular Structures Formed

  • Components from previous steps:

    • Outer membrane: lipopolysaccharide and foreign proteins.

    • Cell wall: Tetragon.

    • Cytoplasmic membrane: phospholipid bilayer.

  • All cell components synthesized from simple precursor metabolites created during catabolic reactions.