Recording-2025-03-26T14:16:28.549Z

Redox Reactions and Enzyme Activity

  • Enzyme Activity Influencers:

    • Factors Affecting Activity:

      • Solute concentration: Higher concentration increases activity.

      • Temperature: Enzymes have optimal temperatures. For instance, an enzyme shows peak activity at 24°C.

      • Activators: Molecules that increase enzyme activity.

      • Inhibitors: Substances that decrease activity, classified into:

        • Competitive inhibitors: Bind at the active site.

        • Non-competitive inhibitors: Bind elsewhere, altering enzyme shape.

  • Covalent vs. Non-Covalent Bonds:

    • Covalent bonds: Irreversible; form when substrates bind very tightly (e.g., certain inhibitors).

    • Non-covalent bonds: Reversible; essential for enzyme-substrate interactions.

Glycolysis

  • Overview:

    • Universal first step in energy production, occurs in all cells (prokaryotes and eukaryotes).

    • Takes place in the cytoplasm.

  • Steps of Glycolysis:

    • Ten Enzyme Process:

      • First five steps (endergonic) consume 2 ATP to prepare substrates.

      • Last five steps produce 4 ATP (net gain of 2 ATP).

      • ATP production through substrate-level phosphorylation.

  • Importance:

    • Produces pyruvates, essential for subsequent cellular respiration pathways.

Cellular Respiration Pathways

  • Types:

    • Aerobic respiration: Requires oxygen.

    • Anaerobic respiration: No oxygen required (e.g., fermentation).

  • Glycolysis Role :

    • Central process leading to either aerobic or anaerobic respiration.

Pyruvate Oxidation and Citric Acid Cycle

  • Pyruvate Oxidation:

    • Connects glycolysis to the citric acid cycle; does not produce ATP but prepares carriers (NADH, FADH2).

  • Citric Acid Cycle:

    • Produces additional 2 ATP via substrate-level phosphorylation.

Electron Transport Chain and Oxidative Phosphorylation

  • Final Step of Cellular Respiration:

    • Takes place in the inner mitochondrial membrane; involved in transforming NADH and FADH2 into ATP.

  • Mechanism:

    • Electrons transferred through proteins in the electron transport chain, pumping H+ ions into the intermembrane space.

    • Creates a gradient utilized by ATP synthase to produce 28 ATP through oxidative phosphorylation.

  • Oxygen's Role:

    • Final electron acceptor; forms water as a byproduct.

  • Recycling:

    • FADH2 and NADH are recycled back to earlier steps to sustain the process.

Key Points to Remember

  • Glycolysis is essential for initiating cellular respiration, regardless of aerobic or anaerobic pathways.

  • Net products of glycolysis: 2 ATP, 2 NADH, and 2 pyruvate.

  • Key enzymes: Understand the role of ATP synthase and the function of specific phases (endergonic vs. exergonic).

  • Overall ATP Yield: Up to 30-32 ATP from complete cellular respiration, contingent on substrate availability and metabolic pathways.