1. Free Energy All living systems require constant input of free energy

2. Metabolism Metabolism: the sum total of all the chemical reaction that take place to build up and break down the materials needed in an organism Catabolism: the breaking down of complex molecules Exergonic: aka Spontaneous – happens on its own w/o energy Releases energy to surroundings/products are more stable than reactants ∆G = - Increases disorder (more entropy) Anabolism: building complex complex molecules Endergonic: aka Nonspontaneous – requires energy to take place Stores or absorbs energy from surroundings/products are less stable than reactants ∆G = + Decreases Disorder (less entropy) Metabolic pathways: begin with specific molecule, altered in a series of defined steps, resulting in certain products Enzyme 1Enzyme 2Enzyme 3 D CB A Reaction 1Reaction 3Reaction 2 Starting molecule Product

3. Reactants Energy Free energy Products Amount of energy released (∆G < 0) Progress of the reaction (a) Exergonic reaction: energy released Products Reactants Energy Free energy Amount of energy required (∆G > 0) (b) Endergonic reaction: energy required Progress of the reaction

4. Fig. 8-6a Energy (a) Exergonic reaction: energy released Progress of the reaction Free energy Products Amount of energy released (∆G < 0) Reactants

5. Fig. 8-6b Energy (b) Endergonic reaction: energy required Progress of the reaction Free energy Products Amount of energy required (∆G > 0) Reactants

6. Forms of Energy Kinetic Energy: motions – can do work by transferring motion to other matter (ex: pool stick – ball to ball) Thermal energy: type of kinetic energy; aka heat; random movement of atoms or molecules Anytime bonds are broken there is a transfer of energy from the molecule to thermal energy (called heat – this is why we say heat is released to the environment through the food chain – when glucose is broken down in the presences of oxygen bonds are broken  some of the energy stored in the bonds of the glucose molecule becomes thermal energy  this thermal energy is either lost to the environment OR if the organisms is an endotherm (relies on internal temperature control vs external (ectotherm)) the heat is used to maintain the organisms temperature (called thermoregulation) Potential Energy: energy matter posses because its location or structure Chemical energy: potential energy available for release in a chemical reaction

7. Climbing up converts the kinetic energy of muscle movement to potential energy. A diver has less potential energy in the water than on the platform. Diving converts potential energy to kinetic energy. A diver has more potential energy on the platform than in the water.

8. Application Describe the forms of energy found in an apple as it grows on a tree, then falls and is digested by someone who eats it.

9. Application Answer The apple has potential energy in its position hanging on the tree, and the sugar and other nutrients it contains have chemical energy. The apple has kinetic energy as it falls from the tree to the ground. When the apple is digested and its molecules broken down, some of the chemical energy is used to do work, and the rest is lost as thermal energy Who knew…so many types of energy in one little apple!!!

10. Thermodynamics Thermodynamics: study of how energy is transferred (passed along) or transformed (changed into a different kind of energy) System: matter under study Universe: everything outside the system Isolated system: system unable to exchange either energy or matter with its surroundings; ex: thermos bottle Open system: energy and matter can be exchanged between the system and its surrounds

11. Laws of Thermodynamics First law: Energy can be transferred and transformed, but it cannot be created or destroyed; principle of conservation of energy Electric Company does not make energy; they convert it to a usable form Plants are not actually energy producers, more accurate to call them energy transformers. Second Law: Every energy transfer or transformation increases the entropy of the universe; for a process to be spontaneous, it must increase the entropy of the universe

12. What is Entropy? Measure of disorder, or randomness The more randomly arrange matter is, the greater its entropy Although order can increase locally, the trend towards randomization of the universe is unstoppable As chemical energy in food (C 6 H 12 O 6 ) is converted into kinetic energy (movement) the release of CO 2 + H 2 O + heat is causing the universe to become more disordered; localized order is increased at the expense of the universe becoming more disordered For a process to occur on its own it must increase the entropy of the universe; no energy is needed If a reaction results in a product that is more ordered than the reactants it is going to require energy and will not take place on its own…endergonic or nonspontaneous

13. Free-Energy Change, ∆G The following is an equation that can be used to determine the free energy available in a chemical reaction: ∆G = ∆H – T∆S ∆G = change in free energy; energy available to do work ∆H = change in system’s enthalpy (in biological systems = total energy) T = absolute temperature in Kelvin (K) ∆S = change in entropy; order of the system If ∆G = -- then the reaction will be spontaneous and occur without energy; if ∆G = + then the reaction will be nonspontaneous and will require energy

14. (a) Gravitational motion (b) Diffusion(c) Chemical reaction More free energy (higher G) Less stable Greater work capacity In a spontaneous change The free energy of the system decreases (∆G < 0) The system becomes more stable The released free energy can be harnessed to do work Less free energy (lower G) More stable Less work capacity

15. Less free energy (lower G) More stable Less work capacity More free energy (higher G) Less stable Greater work capacity In a spontaneous change The free energy of the system decreases (∆G < 0) The system becomes more stable The released free energy can be harnessed to do work ∆G can be negative only when the process involves a loss of free energy during the change from initial state to final state Free energy is the measure of a system’s instability – its tendency to change to a more stable state Unless something prevents matter, it wants to move to a more stable state Free energy (ability to do work) increases when a reaction is somehow pushed away from equilibrium A process is spontaneous and can perform work only when it is moving towards equilibrium

16. Fig. 8-5b Spontaneous change Spontaneous change Spontaneous change (b) Diffusion(c) Chemical reaction(a) Gravitational motion

17. Digestion Time/Application 1.Assume temperature and enthalpy do not change…based on the equation for free energy change, how would entropy need to change in order for ∆G to be negative? Would entropy increase or decrease? If entropy increases, does that mean the reaction causes an increase in disorder or decrease in disorder? 2.Assume temperature and entropy do not change…based on the equation for free energy change, how would enthalpy need to change to cause ∆G to be negative? Would the reactants or products become more or less stable?

18. Digestion Debrieft 1.Increase in entropy (∆S) would lead to a negative ∆G  reaction would INCREASE in disorder 2.Decrease in enthalpy (∆H) would lead to a negative ∆G  the products would be more stable than the reactants; the reaction is exergonic (releasing energy)

19. Three main kinds of work Chemical work: pushing of endergonic reactions, which would not occur spontaneously, such as the synthesis of polymers from monomers Transport work: pumping of substances across membranes against the direction of spontaneous movement Mechanical work: movement (contraction of muscles, beating of cilia, movement of chromosomes during cell division)

20. Energy Coupling Energy coupling: the use of an exergonic process to dive an endergonic reaction ATP is responsible for most energy coupling in cells Structure of ATP (adenosine triphosphate): Essential the RNA adenine nucleotide with two additional phosphate groups 3 Phosphate groups Ribose Adenine

21. Is ∆G negative or positive when ATP becomes ADP? Inorganic phosphate Energy Adenosine triphosphate (ATP) Adenosine diphosphate (ADP) P P P PP P + + H2OH2O i -Which molecule is more stable? -Is there more of less disorder in ATP or ADP? -Is this reaction endergonic or exergonic? -Is this reaction spontaneous or non spontaneous?

22. (b) Coupled with ATP hydrolysis, an exergonic reaction Ammonia displaces the phosphate group, forming glutamine. (a) Endergonic reaction (c) Overall free-energy change P P Glu NH 3 NH 2 Glu i ADP + P ATP + + Glu ATP phosphorylates glutamic acid, making the amino acid less stable. Glu NH 3 NH 2 Glu + Glutamic acid Glutamine Ammonia ∆G = +3.4 kcal/mol + 2 1 How ATP drives chemical work ATP drives endergonic reactions by phosphorylation (transferring a phosphate group to some other molecule) The recipient molecule is now phosphorylated  energy rich and unstable The combined rxns are exergonic

23. (b) Mechanical work: ATP binds noncovalently to motor proteins, then is hydrolyzed Membrane protein P i ADP + P Solute Solute transported P i VesicleCytoskeletal track Motor protein Protein moved (a) Transport work: ATP phosphorylates transport proteins ATP How ATP drives transport and mechanical work The phosphate group from the ATP binds the the protein and causes the shape of the protein to change

24. The Regeneration of ATP ATP is a renewable resource that is regenerated by addition of a phosphate group to adenosine diphosphate (ADP) ADP + P --> ATP The energy to phosphorylate ADP comes from catabolic reactions in the cell. The chemical potential energy temporarily stored in ATP drives most cellular work. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

25. The ATP cycle P i ADP + Energy from catabolism (exergonic, energy-releasing processes) Energy for cellular work (endergonic, energy-consuming processes) + H 2 O ATP

26. How much total energy does an organisms need to stay alive? Metabolic rate: amount of energy an animal uses in a unit of time Can be determined in several ways: Because nearly all of the chemical energy used in cellular respiration eventually appears as heat, metabolic rate can be measured by monitoring an animal’s rate of heat loss Amount of oxygen consumed or carbon dioxide produced Record the rate of food consumption, the energy content of the food and chemical energy lost in waste products Amount of energy is going to differ depending on size, shape, and type of thermoregulation (how an organisms stay warm), age, activity, nutrition, temperature Endotherm: internal Ectotherm: external

27. Size and Metabolic Rate In general smaller organisms have a higher metabolic rate than larger animals; a mouse needs more energy per unit mass compared to an elephant. This does not mean the elephant eats less than the mouse…it means the elephant needs less energy for every square inch of body mass compared to the mouse

28. Activity and Metabolic Rate Increased activity = increased need for energy Decreased activity = decreased need for energy What happens when you have an excess supply of energy? Storage – what does this mean??? What happens when you have a deficient of energy? Organism dies What impact does this have on the population? Ecosystem? Leads to disruptions in ecosystems To conserve on energy during times of stress some organisms go into a Torpor or Hibernation state (long term torpor)