BIOL1004 Study Guide - Final Guide: Atp Synthase, Biological Membrane, Chemiosmosis
Entropy and Enthalpy
• Entropy- internal energy of the system plus the product of heat and volume
• ∆G= ∆H-T∆S
◦ ∆H change in enthalpy, ∆S change in entropy, H is temperature
◦ conditions: concentration, pressure, temperature
◦ ∆G is measured under strictly standardized conditions
◦ When ∆G<0 the reaction is exergonic and proceed spontaneously
◦ When ∆G>0 the reaction is endergonic and will proceed spontaneously in
the reverse direction
◦ When ∆G=0 the system is in equilibrium and the concentrations of the
products and reactants will remain constant
• Entropy- measure of disorder/randomness of a system
• The free energy of a reaction is determined by the amount of heat produced and the
amount of entropy generated
• Chemical reactions require activation energy to proceed even if the reaction is over
all favorable conditions
• Unfavourable reactions can be completed, by coupling reactions that have a ∆G<0
• Living cells make use of energy carriers to couple unfavourable reactions
Energy carriers
• The major energy carriers are ATP and NADH/NADPH
• ATP stores energy by keeping its hydrolysis out of the equation
• NADH facilitates redox reactions
• Nutrients are oxidised to generate carriers ATP and NADH
• Carbohydrates are oxidised by the glycolysis pathway
◦ First part: 2ATP molecules split glucose in half
◦ Second part: 4 ATP molecules are generated and 2 NADH are produced
◦ Further oxidation of pyruvate to CO2 and H2O, in mitochondria, yields up to
36 molecules of ATP
◦ In fermentation only 2ATP are produced
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