AS

Key Concepts of Metabolism and Energy Production

Metabolism Basics

  • Metabolism involves breaking down substances to extract energy.

  • Photosynthesis involves building substances, the next chapter will cover this.

Electron Transfer and Redox Reactions

  • Gaining electrons = reduction; NADH gained electrons and protons.

  • Movement of hydrogen often accompanies electron movement in redox reactions.

  • NADH is higher in energy compared to ATP.

NADH and FADH2

  • NADH = reduced form of nicotinamide adenine dinucleotide (energy carrier).

  • FADH2 = reduced form of flavin adenine dinucleotide, slightly less energetic than NADH.

  • Both are used in respiration and ultimately produce ATP.

Glycolysis Net Gain

  • Glycolysis yields 2 net ATP after using 2 ATP to generate 4 ATP (total 4 ATP).

  • It can produce ATP without oxygen via fermentation, which recycles NAD+.

Electron Transport Chain (ETC)

  • Main purpose is to create a proton gradient; does not directly produce ATP.

  • Reduces oxygen to water at the end; the only place oxygen is used in metabolism.

  • Proton gradient powers ATP synthase for ATP production (oxidative phosphorylation).

ATP Synthase

  • ATP synthase utilizes the proton gradient to synthesize ATP from ADP.

  • Historically misunderstood as a pump for protons; actually uses proton flow to generate ATP.

Energy Output Variability

  • Energy yield from oxidative phosphorylation varies (26-28 ATPs); influenced by mitochondrial health.

  • RXN efficiency can vary based on individual conditions and mitochondrial function.

Fermentation

  • Occurs when oxygen is absent to regenerate NAD+ for glycolysis; produces minimal ATP.

  • Involves conversion of pyruvate to either lactic acid or ethanol based on organism type.

Negative Feedback Regulation

  • Citrate from the citric acid cycle inhibits glycolysis, exemplifying negative feedback regulation.