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.