Bioenergetics Revision Sheet

1. 📌 Essentials

• Life relies on extraction, transformation, and dissipation within cells- Systems: open (exchange matter/energy), closed (energy only), isolated (no exchange).
• First law: energy conserved; ΔU = Q + W.
• Enthalpy (H): heat exchange at constant pressure; ΔH > 0 endothermic, ΔH < 0 exothermic.
• Spontaneous reactions: ΔG < 0; depend on ΔH and ΔS.
• Entropy (S): measure of disorder; increases in spontaneous processes.
• Gibbs free energy (G): ΔG = ΔH - T ΔS; determines reaction spontaneity.
• Equilibrium: ΔG = 0; ΔG° relates to equilibrium constant K.
• Redox reactions: electron transfer; characterized by reduction potentials (E°).
• Energy forms: caloric, electrical, chemical, nuclear, mechanical.
• Biological systems are open thermodynamic systems constantly exchanging energy and matter.

2. 🧩 Key Structures & Components