Lehninger Chapter 13: Principles of Bioenergetics PDF

 What makes a reaction go? Energetics/Thermodynamics Calculate enthalpy change of a reaction: Sum Enthalpy (Products) minus Sum Enthalpy (Reactants)  Energetics/Thermodynamics As time moves forw...

 What makes a reaction go? Energetics/Thermodynamics Calculate enthalpy change of a reaction: Sum Enthalpy (Products) minus Sum Enthalpy (Reactants)  Energetics/Thermodynamics As time moves forward, the net entropy (degree of disorder) of any isolated or closed system will increase. It takes *a lot* of effort (energy?) to decrease entropy.  Energetics/Thermodynamics Gibbs Free Energy (G) is the available energy in a system to do work. Energetics/Thermodynamics  Keq = concentration Equilibrium products/concentration reactants One can compare where the reaction is going when you used Q and compare it to Keq. Given the concentrations of all of the constituents and the Keq. Q= Completion depends on a specific set of concentrations, described by an Equilibrium Constant, Keq Q= This means that ∆G changes based on concentrations of reactants/products! Energetics/Thermodynamics IF: Keq >> 1, ∆G° is large and negative → meaning? IF: Keq 0) create order and require work and energy. We gotta get that energy from somewhere. Energy Releasing Reaction? ATP and other compounds! Energy Releasing Reaction? ATP and other compounds! Remember? Nucleotide! ATP and those “Other Compounds” mol ATP and those “Other Compounds” - Thioesters You will see Acetyl-CoA everywhere in metabolism! CAC, Fatty Acid Metabolism, Amino acid metabolism Energy Releasing Reaction? ATP  What is so special about ATP? ATP is “mid” Using “high energy compounds” to carry out “low energy” reactions is a waste of energy. Using PEP (-70 kJ/mol) to help out a -20 kJ/mol reaction is a waste of 50 kJ/mol Whereas using ATP (~30-35 kJ/mol) would be a “waste” of 10-15 kJ/mol → efficient  What is so special about ATP? ATP is versatile It can transfer and receive phosphate groups and energy to and from high and low energy compounds ATP can undergo several different hydrolysis reactions, yielding different products and energies depending on need (stay tuned) More than hydrolysis → group transfers But also… See, ATP is versatile! See, ATP is versatile! – Example Big energy hill to climb! Adenylylation (transferring an AMP) gives a lot of energy AMP’ed up if you will… Fatty acid, amino acid activation, DNA/RNA synthesis Typically…and you’ll see this a lot – Phosphoryl Group Transfers Phosphoryl Group Transfers Phosphoryl Group Transfers - Creatine Oxidation/Reduction Oxidation/Reduction Tips and things: More H’s → more reduced More O’s → more oxidized Oxidation → loss of electrons or time spent with electrons Oxygens pull electron density away from carbon Oxidation/Reduction  Mobile!/Loosely bound coenzyme Transfers electrons in pairs! Electron shuttle!  Vitamin B3 Supplements Tuna, Peanuts, Salmon, Turkey, Chicken, Sunflower seeds, beef, pork  Tightly bound to flavoproteins Holds electrons for the cells Is the redox bit (cofactor) of the enzyme protein  Vitamin B2 Supplements Meat, yogurt, cheese, eggs, fortified grains, nuts, spinach Vegetarians and pregnant people at high risk of deficiency