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Metabolism and Energy Chapters 8 Metabolism and Energy Metabolism Catabolism Anabolism Bioenergetics Energy Kinetic Heat/Thermal Light Energy Potential Chemical Organisms are energy transformers! Metabolism and Energy Metabolism Organisms are energy transformers! Metabolic pathway begins with a specific molecule, which is then altered in a series of defined steps leading to a specific product Each step is catalyzed by a specific enzyme Metabolism and Energy Metabolism Organisms are energy transformers! Catabolism Energy released (helps to drive anabolic pathways). Ex: cellular respiration sugar put in to the body is broken down to do work in the cell (movement, active transport, etc). Metabolism and Energy Metabolism Organisms are energy transformers! Catabolism Anabolism sometimes called biosynthetic pathways- Ex: synthesis of a protein from amino acids. Energy required/absorbed. Metabolism and Energy Metabolism Catabolism Organisms are energy transformers! Anabolism Bioenergetics the study of how energy flows through living systems. Metabolism and Energy Metabolism Catabolism Anabolism Organisms are energy transformers! Bioenergetics Energy the capacity to cause change. Some forms of energy can be used to do work- or move matter against opposing forces Ex: (friction and gravity) Ability to rearrange a collection of matter Metabolism and Energy Energy Organisms are energy transformers! Kinetic Relative motion of objects moving objects can perform work by imparting motion to other matter. Ex: Moving water through a dam turns turbines, moving bowling ball knocks over pins Metabolism and Energy Organisms are energy transformers! Energy Kinetic Heat/Thermal comes from the movement of atoms or molecules associated with kinetic energy Metabolism and Energy Organisms are energy transformers! Energy Kinetic Heat/Thermal Light Energy Type of energy that can be harnessed to perform work Ex. Powering Photosynthesis Metabolism and Energy Kinetic Organisms are energy transformers! Heat/Thermal Light Energy Potential Non-kinetic energy because of location or structure, height, chemical bonds, etc. Metabolism and Energy Kinetic Heat/Thermal Light Energy Organisms are energy transformers! Potential Chemical the potential energy available for release by a reaction. Ex: Glucose is high in chemical energy and the process of glycolysis breaks it down. As bonds are broken, energy is released, but bonds also reform to make new molecules, thus it uses some energy. Metabolism and Energy Organisms are energy transformers! All original energy comes from light. (photosynthesis- primary producer- consumerwho changes it from chemical to kinetic and releases thermal. Thermodynamics What is Thermodynamics? Thermodynamics The energy transformations that occur in a collection of matter Thermodynamics Thermodynamics System vs. Surroundings Isolated System vs. Open System First Law of Thermodynamics Thermodynamics Two Laws of Thermodynamics govern energy exchange: First Law of Thermodynamics Second Law of Thermodynamics Thermodynamics Two Laws of Thermodynamics govern energy exchange: First Law of Thermodynamics energy cannot be created or destroy Only transferred or transformed Known as Principle of conservation of energy Thermodynamics Second Law of Thermodynamics During energy transfer, some energy become unusable energy (unavailable to do work) Entropy (S) – Measure of disorder or randomness Thermodynamics So, What is the Second Law of Thermodynamics? Every energy transfer or transformation increases the entropy of the universe Thermodynamics Spontaneous (Energetically Favorable) vs. Nonspontaneous Processes Leads to the second way we state the 2nd Law of Thermodynamics: For a process to occur spontaneously, it must increase the entropy of the universe Think-Pair-Share How does the second law of thermodynamics help explain the diffusion of a substance across a membrane? If you place a teaspoon of sugar in the bottom of a glass of water, it will dissolve completely over time. Left longer, eventually the water will disappear and the sugar crystals will reappear. Explain these observations in terms of entropy. Gibbs Free Energy Free Energy Portion of system’s energy that can perform work when temp and pressure are uniform throughout system ΔG = free energy of a system -ΔG = spontaneous reaction +ΔG = nonspontaneous reaction ΔG = 0 = Dead Cell (can do no work) ΔG = ΔH – TΔS ΔG = ΔGfinal – ΔGinitial Enthalpy Gibbs Free Energy ΔG = ΔH – TΔS ΔG = ΔGfinal – ΔGinitial ΔH = he change in the system’s enthalpy What is enthalpy? Total energy ΔS = change in system’s entropy T = absolute Temperature in Kelvin Gibbs Free Energy ΔG = ΔH – TΔS ΔG = ΔGfinal – ΔGinitial Can think of this as difference in final state and initial state Gibbs Free Energy Endergonic vs. Exergonic Reactions +ΔG Non-Spontaneous -ΔG Spontaneous Gibbs Free Energy Reactions in isolates system eventually reach equilibrium and then cannot do work Metabolism reactions are reversible and eventually will reach equilibrium Living cell is not in equilibrium Some reactions are constantly pulled in one direction and this keeps them from reaching equilibrium Warm Up Exercise Glow in the dark necklaces are snapped in a way that allows two chemicals to mix and they glow. Is this an endergonic or exergonic reaction? Explain. In simple diffusion, H+ ions move to an equal concentration on both sides of a cell membrane. In cotransport, H+ ions are pumped across a membrane to create a concentration gradient. Which situation allows the H+ ions to perform work in the system? ATP and Cellular Work Three Types of Work Chemical Transport Mechanical Energy Coupling Phosphorylated Intermediate Why is ATP such a good energy molecule? What is ATP? Contains ribose sugar, nitrogenous base adenine, and chain of 3 phosphate groups bonded to it. Bonds can be broken by hydrolysis Why is ATP such a good energy molecule? When bond is broken , a molecule of inorganic phosphate leaves the ATP It become adenosine diphosphate (ADP) Is Hydrolysis of ATP endergonic and exergonic? Anabolic or catabolic? Does it release -7.3 kcal / mol in the cell? ATP Hydrolysis kh ATP and Cellular Work ATP Cycle The body regenerates 10 million molecules of ATP per second per cell! Enzymes Enzymes- biological catalyst Substrates – reactants that bind to the enzyme, usually in the active site Enzymes Activation Energy (EA) the energy required to get a reaction started. Many times this energy is absorbed as thermal energy from the environment Many times room temperature may be enough, but most reactants need more energy than that to get started. AKA = free energy of activation Enzymes Activation Energy (EA) the energy required to get a reaction started. How does heat effect an enzyme? Heat speeds a reaction by allowing reactants to attain the transition state more often This solution is inappropriate for biological systems because it would denature proteins and kill cells. Additionally, it would speed up all reactions, not just those that are needed. Enzymes Enzymes catalyze reactions by lowering the activation energy. Enzymes Enzyme + Substrate = Enzyme-Substrate Complex Enzyme + Substrate(s) EnzymeSubstrate Complex Enzyme + Product(s) Enzymes Active Site pocket or groove on the surface of the enzyme where the substrate binds and catalysis occurs. Enzymes Induced Fit When the substrate enters the active site, it forms weak bonds with the enzyme, inducing a change in the shape of the protein. This change allows additional weak bond (ie: hydrogen bonds) to form, causing the active site to fit around the substrate snugly- Effects of Environment Changes in the environment of the enzyme can cause inefficiencies or denaturation of the enzyme: Temperature pH Concentration of Enzyme Concentration of Substrate Enzymes Cofactors nonprotein components that help in catalytic activity. Usually bound to enzyme (sometimes permanently, sometimes loosely) Coenzyme If cofactor is organic Many vitamins are important because they are coenzymes or make up coenzymes Enzyme Action Competitive Inhibitors Resembles normal substrate molecule Reduce productivity of enzyme by blocking substrates from entering active sites Enzyme Action Noncompetitive Inhibitors Don’t directly compete with substrate Impede enzymatic reactions by binding to another part of the enzyme Allosteric Regulation Allosteric Regulation Term used to describe any case in which a protein’s function at one site is affected by the binding of a regulatory molecule to a separate site Can be inhibition or stimulation Generally constructed from two or more subunits Allosteric Site regulatory site Both activators and inhibitors can bind to these sites: Activator stabilizes functional active site Inhibitors stabilizes inactive form Shape change in one subunit affects shape of other subunit Cooperativity A different type of allosteric activation in which a substrate binds to an active site stimulating the catallytic powers of a multisubunit enzyme by affecting other active sites Cooperativity Amplifies the response of enzymes to substrates An induced fit in one subunit can trigger the same favorable shape change in other subunits Feedback Inhibition Metabolic pathway switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway Feedback Inhibition
