Lecture Notes on Cellular Respiration and Metabolism

Introduction

• Attendance Reminder: Scan attendance.
• Lecture Outline:
  • Complete Chapter 6 (Metabolism)
  • Begin Chapter 7 (Cellular Respiration)
  • Cover complex processes and cellular respiration in detail.

Metabolism Recap

• Inhibitors:
  • Competitive Inhibitors: Interfere with active sites, preventing substrate binding.
  • Non-Competitive Inhibitors: Bind to allosteric sites, changing enzyme shape.
• Metabolism Definition: All chemical reactions in an organism for energy harvesting and molecule synthesis.
  • Anabolic Reactions: Energy-expending, building molecules.
  • Catabolic Reactions: Energy-yielding, breaking down molecules.
• Biochemical Pathways: Sequence of reactions where the product of one reaction is the substrate for the next.

Feedback Inhibition

• Mechanism: End product acts as an inhibitor to prevent overproduction.
• Example: Breastfeeding regulation of milk production.

Cellular Respiration Introduction

• Definition: Process by which cells harvest energy through breakdown of glucose and oxygen into CO2, H2O, heat, and ATP.
• Types of Organisms:
  • Autotrophs: Produce own organic molecules via photosynthesis.
  • Heterotrophs: Rely on organic compounds from other organisms.

Key Concepts in Cellular Respiration

• Redox Reactions:
  • Oxidation: Loss of electrons.
  • Reduction: Gain of electrons.
  • Dehydrogenation: Loss of hydrogen atoms.
• Aerobic vs. Anaerobic Respiration:
  • Aerobic: In presence of oxygen, yielding more ATP.
  • Anaerobic/Fermentation: Without oxygen.

Glycolysis

• Location: Cytoplasm.
• Process: Conversion of glucose to pyruvate through a 10-step process.
• Net Production: 2 ATP and 2 NADH.
• Phases:
  • First 5 steps consume ATP.
  • Last 5 steps produce ATP and NADH.

NAD+ and NADH

• Role: NAD+ reduced to NADH, carrying high-energy electrons to ATP production pathways.

Respiration Process

• Aerobic Respiration: Oxygen as final electron acceptor, producing significant ATP.
• Anaerobic Respiration (Fermentation): Organic molecule as the final electron acceptor.

Pyruvate Oxidation

• In Presence of Oxygen: Pyruvate becomes acetyl-CoA, entering the mitochondria and the citric acid cycle.
• Pyruvate to Acetyl-CoA: Releases CO2, forms NADH and acetyl-CoA.

Citric Acid Cycle (Krebs Cycle)

• Location: Mitochondria.
• Process: Oxidation of acetyl group into CO2, producing NADH, FADH2, and ATP.
• Cycle Phases: Addition of acetyl group to oxaloacetate, decarboxylation, and regeneration of oxaloacetate.
• Yield: Per glucose (two cycles): 4 CO2, 6 NADH, 2 FADH2, 2 ATP.

Conclusion

• Reminder: Review content for upcoming classes as the next sections will be more detail-oriented.