Energy and MetabolismThe Energy of LifeMetabolic PathwaysMetabolic PathwayBioenergeticsEnergyForms of EnergyLaws of Energy TransformationThe First Law of ThermodynamicsSecond Law of ThermodynamicsSlide 11Biological Order and DisorderSlide 13Free EnergyExergonic reactionsEndergonic ReactionsSlide 17Equilibrium and MetabolismSlide 19An Analogy For Cellular Respiration – Glucose CatabolismEnergy CouplingThe Structure and Hydrolysis of ATPSlide 23Cellular WorkEnergy Coupling - ATP / ADP CycleHow ATP Performs WorkSlide 27Activation EnergyReaction RatesIncreasing Reaction RatesEnzymes Lower the EA BarrierEnzymes Are Biological CatalystsSubstrate Specificity of EnzymesThe Catalytic Cycle Of An EnzymeSlide 35Factors Affecting Enzyme ActivityEffects of Temperature and pHSlide 38Slide 39Enzyme InhibitorsSlide 41Regulation Of Enzyme Activity Helps Control MetabolismAllosteric Activation and InhibitionAllosteric Regulation of EnzymesCooperativitySlide 46Regulation of Biochemical PathwaysFeedback Inhibition1Energy and Metabolism2The Energy of Life •The living cell generates thousands of different reactions•Metabolism•Is the totality of an organism’s chemical reactions•Arises from interactions between molecules•An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics3Metabolic Pathways•Biochemical pathways are the organizational units of metabolism•Metabolism is the total of all chemical reactions carried out by an organism•A metabolic pathway has many steps that begin with a specific molecule and end with a product, each catalyzed by a specific enzyme•Reactions that join small molecules together to form larger, more complex molecules are called anabolic.•Reactions that break large molecules down into smaller subunits are called catabolic.Enzyme 1 Enzyme 2 Enzyme 3ABCDReaction 1 Reaction 2 Reaction 3StartingmoleculeProduct4Metabolic Pathway•A sequence of chemical reactions, where the product of one reaction serves as a substrate for the next, is called a metabolic pathway or biochemical pathway•Most metabolic pathways take place in specific regions of the cell.5Bioenergetics•Bioenergetics is the study of how organisms manage their energy resources via metabolic pathways•Catabolic pathways release energy by breaking down complex molecules into simpler compounds•Anabolic pathways consume energy to build complex molecules from simpler ones6Energy•Energy is the capacity to do work or ability to cause change. Any change in the universe requires energy. Energy comes in 2 forms:•Potential energy is stored energy. No change is currently taking place•Kinetic energy is currently causing change. This always involves some type of motion.7Forms of Energy•Kinetic energy is the energy associated with motion•Potential energy•Is stored in the location of matter•Includes chemical energy stored in molecular structure•Energy can be converted from one form to anotherOn the platform, a diverhas more potential energy.Diving converts potentialenergy to kinetic energy.Climbing up converts kineticenergy of muscle movement to potential energy.In the water, a diver has less potential energy.8Laws of Energy Transformation•Thermodynamics is the study of energy changes.•Two fundamental laws govern all energy changes in the universe. These 2 laws are simply called the first and second laws of thermodynamics:9The First Law of Thermodynamics•According to the first law of thermodynamics•Energy cannot be created or destroyed•Energy can be transferred and transformedFor example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movementChemicalenergy10Second Law of Thermodynamics•The disorder (entropy) in the universe is continuously increasing.•Energy transformations proceed spontaneously to convert matter from a more ordered, less stable form, to a less ordered, more stable form•Spontaneous changes that do not require outside energy increase the entropy, or disorder, of the universe•For a process to occur without energy input, it must increase the entropy of the universe11•During each conversion, some of the energy dissipates into the environment as heat.•During every energy transfer or transformation, some energy is unusable, often lost as heat•Heat is defined as the measure of the random motion of molecules•Living cells unavoidably convert organized forms of energy to heat•According to the second law of thermodynamics, every energy transfer or transformation increases the entropy (disorder) of the universeSecond Law of ThermodynamicsFor example, disorder is added to the cheetah’ssurroundings in the form of heat and the small molecules that are the by-products of metabolism.Heatco2H2O+12Biological Order and Disorder•Cells create ordered structures from less ordered materials•Organisms also replace ordered forms of matter and energy with less ordered forms•The evolution of more complex organisms does not violate the second law of thermodynamics•Entropy (disorder) may decrease in an organism, but the universe’s total entropy increases13Biological Order and Disorder•Living systems•Increase the entropy of the universe•Use energy to maintain order•A living system’s free energy is energy that can do work under cellular conditions•Organisms live at the expense of free energy50µm14Free Energy•Free energy is the portion of a system’s energy that is able to perform work when temperature and pressure is uniform throughout the system, as in a living cell•Free energy also refers to the amount of energy actually available to break and subsequently form other chemical bonds•Gibbs’ free energy (G) – in a cell, the amount of energy contained in a molecule’s chemical bonds (T&P constant)•Change in free energy - ΔG •Endergonic - any reaction that requires an input of energy•Exergonic - any reaction that releases free energy15Exergonic reactions•Reactants have more free energy than the products •Involve a net release of energy and/or an increase in entropy•Occur spontaneously (without a net input of energy)ReactantsProductsEnergyProgress of the reactionAmount ofenergyreleased (∆G <0)Free energy(a) Exergonic reaction: energy released16Endergonic Reactions•Reactants have less free energy than the products•Involve a net input of energy and/or a decrease in entropy•Do not occur spontaneouslyEnergyProductsAmount