Energetics Fueling Life

Energy takes various forms MECHANICALL

Energy, regardless of the form, can exist in two states potential kinetic

Energy is made available to organisms Photosynthesis Radiant (light) into chemical (CH2O)

Energy is made available to organisms Respiration Chemical (organic molecules) into chemical (ATP) Plants do both energy conversions

Energy is used for cell work Growth and development movement Thermoregulation Nerve transmission

All metabolic reactions in organisms involve energy transfers Energy transferred as atoms & bonds rearranged The metabolic reactions are paired In general, one is the inverse of the other All are coupled with ATP ATP is either used or produced

example: organic molecule metabolism dehydration hydrolysis building molecules breaking down molecules storing energy releasing energy increasing complexity simplifying creating order increasing disorder

Anabolic Catabolic Build complexity Require a net input of energy ex: photosynthesis Require a net input of energy therefore not spontaneous Catabolic break down molecules ex: respiration Stored energy is released spontaneous

Food eaten Energy + products for synthesis of needed molecules Energy and molecular products

Edit this slide! Oxidation-reduction (redox) reactions 3 reactions described as redox: transfers of O transfers of H transfers of e- Oxidation = gain of O; loss of H; or loss of e- Reduction: loss of O; gain of H; gain of e-. 3 reactions described as redox: transfers of O; transfers of H; transfers of e-. Oxidation = gain of O; loss of H; or loss of e- Reduction: loss of O; gain of H; gain of e-. Do not confuse oxidation with oxidizing AGENT – an oxidizing agent is being reduced!

In redox rxns, energy is transferred as electrons are transferred 3 reactions described as redox: transfers of O; transfers of H; transfers of e-. Oxidation = gain of O; loss of H; or loss of e- Reduction: loss of O; gain of H; gain of e-. Do not confuse oxidation with oxidizing AGENT – an oxidizing agent is being reduced! bonds broken electrons transferred new bonds made energy transferred H is oxidized; F is reduced OIL RIG

Reactions either store or release energy Greater energy In products Endergonic nrg of reactant < product ex: anabolic, oxidation Exergonic nrg of reactant > product ex: catabolic, reduction Less energy in reactants Higher energy reactants Lower energy products

Intermission TED talk: Bioluminescence

Recap: rxn pairs anabolic & catabolic endergonic & exergonic ATP-coupled rxn anabolic & catabolic endergonic & exergonic oxidation & reduction

Reactions for Life Reflect the Laws of Thermodynamics* Despite creationist claims to the contrary, highly ordered life does not violate the second law of T. Because although we can use energy to create order her eon Earth, the over all randomness of the universe is increasing. * The study of energy transformations

Energy amount is constant The universe is a closed system regarding both energy and matter Energy amount is constant The energy into a rxn = the energy at completion

Ex: Photosynthesis energy in = energy out Matter in = Matter out Both matter & energy are conserved (it’s the law!)

Energy form however, is not constant Energy is transformed at every step

Free energy useful to life + Energized atoms not useful ____ heat Free energy This is why there are not 15 trophic levels in a food web Free energy useful to life + Energized atoms not useful ____ = Total Energy

Second Law of Thermodynamics • No physical process finishes with as much available, or useful, energy as it started with Brownian motion Entropy in a closed system can never decrease. As long as entropy is defined as unavailable energy,

Second Law of Thermodynamics Brownian motion • unavailable energy reflects the random kinetic energy of molecules, allowed to spread out • Often this means - the energy transformation includes tnsformation to heat - small molecules result from the break down of larger ones - an ordered system becomes more disordered Entropy in a closed system can never decrease. As long as entropy is defined as unavailable energy,

Entropy happens it’s the Law!

QUANTIFYING ENERGY TRANSFORMATIONS total energy = useable energy* + unusable energy available for work random atomic motion *point of interest for biologists OR useable energy = total energy - unusable energy available for work random atomic motion

useable = total _ unuseable energy energy energy This relationship can be used to determine the energy change of a rxn: exergonic or endergonic? useable = total _ unuseable energy energy energy (change in) Rename the variables: (GIBBS) FREE ENERGY = ENTHALPY - ENTROPY Spontaneity does not imply that the reaction proceeds with great speed. For example, the decay of diamonds into graphite is a spontaneous process that occurs very slowly, taking millions of years. The rate of a reaction is independent of its spontaneity, and instead depends on the chemical kinetics of the reaction. Every reactant in a spontaneous process has a tendency to form the corresponding product. This tendency is related to stability. Stability is gained by a substance if it is in a minimum energy state or is in maximum randomness. Only one of these can be applied at a time. e.g. Water converting to ice is a spontaneous process because ice is more stable since it is of lower energy. However, the formation of water is also a spontaneous process as water is the more random state. So: as entropy increases, free energy decreases

Gibbs = entHalpy - Temp K ( diSorder) To Know: G = H – T ( S) Gibbs = entHalpy - Temp K ( diSorder) (aka entropy) • If G is negative, the reaction is exergonic occurs spontaneously; disorder is increased • If G is positive, the reaction is endergonic order/complexity is increased • requires coupling with an exergonic rxn to drive the process: ATP -> ADP + P In other words, the energy released from one reaction (spontaneous ones) will, in effect, drive other reactions which are not energetically favored (non-spontaneous ones).

Energy released Spontaneous Exergonic G is negative Energy required Non-spontaneous Endergonic G is positive

Building or breaking down molecules? Decreasing or increasing complexity? Catabolic or anabolic? Energy stored or released? Endergonic or exergonic? Chemical reactions can be “coupled” together if they share intermediates. In this case, the overall Gibbs Free Energy change is simply the sum of the ∆G values for each reaction. Therefore, an unfavorable reaction (positive ∆G1) can be driven by a second, highly favorable reaction (negative ∆G2 where the magnitude of ∆G2 > magnitude of ∆G1). For example, the reaction of glucose with fructose to form sucrose has a ∆G value of +5.5 kcal/mole. Therefore, this reaction will not occur spontaneously. The breakdown of ATP to form ADP and inorganic phosphate has a ∆G value of -7.3 kcal/mole. These two reactions can be coupled together, so that glucose binds with ATP to form glucose-1-phosphate and ADP. The glucose-1-phosphate is then able to bond with fructose yielding sucrose and inorganic phosphate. The ∆G value of the coupled reaction is -1.8 kcal/mole, indicating that the reaction will occur spontaneously. This principle of coupling reactions to alter the change in Gibbs Free Energy is the basic principle behind all enzymatic action in biological organisms.[10 For a reaction that is not spontaneous ΔG is positive. This means that work must be done on the system (through some outside intervention) to force the non-spontaneous reaction to occur. The minimum work that must be done is given by ΔG. This tells us that in order to create order in the universe, our bodies must somehow do work to force non-spontaneous reactions to occur. Our bodies do this by consuming fuel that, when oxidized, provides excess Gibbs free energy with which to do work. By combining the oxygen we breathe with the food we eat, we can generate excess Gibbs free energy to force otherwise non-spontaneous reactions to occur. Increasing or decreasing disorder? Change in G positive or negative? Spontaneous or coupled with ATPrxn?

2H2O2 -> 2H2O + 02 Building or breaking down molecules? Decreasing or increasing complexity? Catabolic or anabolic? Energy stored or released? Endergonic or exergonic? Chemical reactions can be “coupled” together if they share intermediates. In this case, the overall Gibbs Free Energy change is simply the sum of the ∆G values for each reaction. Therefore, an unfavorable reaction (positive ∆G1) can be driven by a second, highly favorable reaction (negative ∆G2 where the magnitude of ∆G2 > magnitude of ∆G1). For example, the reaction of glucose with fructose to form sucrose has a ∆G value of +5.5 kcal/mole. Therefore, this reaction will not occur spontaneously. The breakdown of ATP to form ADP and inorganic phosphate has a ∆G value of -7.3 kcal/mole. These two reactions can be coupled together, so that glucose binds with ATP to form glucose-1-phosphate and ADP. The glucose-1-phosphate is then able to bond with fructose yielding sucrose and inorganic phosphate. The ∆G value of the coupled reaction is -1.8 kcal/mole, indicating that the reaction will occur spontaneously. This principle of coupling reactions to alter the change in Gibbs Free Energy is the basic principle behind all enzymatic action in biological organisms.[10 For a reaction that is not spontaneous ΔG is positive. This means that work must be done on the system (through some outside intervention) to force the non-spontaneous reaction to occur. The minimum work that must be done is given by ΔG. This tells us that in order to create order in the universe, our bodies must somehow do work to force non-spontaneous reactions to occur. Our bodies do this by consuming fuel that, when oxidized, provides excess Gibbs free energy with which to do work. By combining the oxygen we breathe with the food we eat, we can generate excess Gibbs free energy to force otherwise non-spontaneous reactions to occur. Increasing or decreasing disorder? Change in G positive or negative? Spontaneous or coupled with ATP?