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Chapter 8

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Chapter 8

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  1. Chapter 8 An Introduction to Metabolism

  2. Chapter 8 – An Introduction to Metabolism AIM: How is matter and energy transformed? Word Roots: cata- = down ana- = up kinet- = movement therm- = heat ex- = out endo- = within allo- = different

  3. Chapter 8 – An Introduction to Metabolism AIM: How is matter and energy transformed? • Metabolism • The sum of an organism’s chemical reactions • Molecules being altered in a series of steps resulting in a product • Catabolism • Anabolism Enzyme 1 Enzyme 2 Enzyme 3 A B C D Chemical Reactions

  4. Chapter 8 – An Introduction to Metabolism ffden-2.phys.uaf.edu AIM: How is matter and energy transformed? • Energy • Kinetic • Potential • Thermal • Chemical ? www.wildlandfire.com

  5. Chapter 8 – An Introduction to Metabolism AIM: How is matter and energy transformed? The laws that govern energy Thermodynamics – the study of the energy transformations that occur in a collection of matter. The 1st law of thermodynamics • Energy cannot be created or destroyed. It can only change forms. • Conservation of Energy What does that tell you about the total energy in the universe? It is always the same.

  6. Chapter 8 – An Introduction to Metabolism AIM: How is matter and energy transformed? The 2nd law of thermodynamics - With EVERY transfer of energy a bit is leaked to the surroundings (you can never transfer 100% of the energy) and in turn the universe ALWAYS becomes more disordered over time. The question is, what does “disordered” mean? Physical disintegration of a systems organized structure

  7. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: How is matter and energy transformed? AIM: Explain “energy” and how it behaves. Disorder Fill it with gasoline and start using it. The chemical PE of the gas will be transferred to the engine as it gets burned causing the engine to move and rotate, which will transfer KE to the wheels. As you drive you are transferring KE to the air and the road as friction. All along, what is happening to your car?

  8. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: How is matter and energy transformed? AIM: Explain “energy” and how it behaves. Disorder - DNA will mutate as we are hit with UV light (energy transfer).

  9. Chapter 8 – An Introduction to Metabolism Heat co2 + H2O Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. (b) Figure 8.3  Chapter 8 - An Introduction to Metabolism AIM: How is matter and energy transformed? AIM: Explain “energy” and how it behaves. Disorder Cheetah converting chemical energy stored in food to kinetic energy in muscle contractions to run, disorder added to surroundings in the form of heat and by-products of metabolism

  10. Chapter 8 – An Introduction to Metabolism AIM: How is matter and energy transformed? The 2nd law of thermodynamics Entropy • The terms we use to measure disorder. • The greater the entropy, the greater the disorder (the further away we are from the desired state). - With EVERY transfer or transformation increases the entropy of the universe

  11. Chapter 8 – An Introduction to Metabolism Chemical energy Heat co2 + H2O (a) First law of thermodynamics: Energy can be transferred or transformed but Neither created nor destroyed. For example, the chemical (potential) energy in food will be converted to the kinetic energy of the cheetah’s movement in (b). Figure 8.3  Second law of thermodynamics: Every energy transfer or transformation increases the disorder (entropy) of the universe. For example, disorder is added to the cheetah’s surroundings in the form of heat and the small molecules that are the by-products of metabolism. (b) Figure 8.3  AIM: How is matter and energy transformed? Summary

  12. Chapter 8 – An Introduction to Metabolism AIM: How is matter and energy transformed? How are we [life] able to be so ordered? Now let’s talk about life (think of humans). What do we define as ordered? • Organisms create order using energy. • Energy flows into the ecosystem as light (via anabolism) and leaves as heat (via catabolism) • Disorder of the universe increases.

  13. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Endergonic Reactions • Reactions that require energy to happen (need something to accelerate them) ADP + Pi ATP The synthesis of ATP 6CO2 + 6H2O  C6H12O6 + 6O2 photosynthesis -Absorbs free energy from its surroundings -Stores free energy in its molecules

  14. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Fig 5.3A endergonic The products contain more energy (have a greater ability to accelerate matter) than the molecules that reacted to make them.

  15. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Energonic reactions are said to be: NOT spontaneous (they do not spontaneously happen [occur by themselves] – they NEED an input of energy)

  16. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Exergonic Reactions • Reactions that transfers energy away (gives off energy) ATP  ADP + Pi Hydrolysis of ATP C6H12O6 + 6O2  6CO2 + 6H2O cellular respiration -Both of these reactions will occur without the input of outside energy (other than activation energy)

  17. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” exergonic Fig 5.3B The products contain less energy (have a lesser ability to accelerate matter) than the molecules that reacted to make them.

  18. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Exergonic reactions are said to be: Spontaneous (they do spontaneously happen [occur by themselves] – no energy input required)

  19. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. How can we describe the energy in substances that is available to accelerate matter (do work)? This available energy is called FREE ENERGY (energy that if free – meaning available – to accelerate matter) Free energy = Gibbs Free Energy = G

  20. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Let’s go back now and look at endergonic and exergonic reactions with Free Energy (G) in mind…

  21. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Endergonic Reactions Reactions that require energy to happen (need something to accelerate them): ADP + Pi ATP The synthesis of ATP ΔG = +7.3 kcal/mol ΔG = the change in (Δ) free energy (G) as you go from reactants to products Therefore: 1. The product (ATP) has more AVAILABLE energy than the reactants (ADP and P). Every mole of ATP has 7.3 kcal more available energy than a mole of ADP and P. 2. A +ΔG tells you the reactions is endergonic and therefore NOT SPONTANEOUS

  22. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy” AIM: Describe chemical reactions in terms of “energy”. Endergonic Reactions How about photosynthesis? What do you know for sure about ΔG? You know that photosynthesis doesn’t happen without an input of energy to get those electrons to move from water to CO2 and therefore if you input energy the products should have more available energy than the reactants…ΔG will be positive. 6CO2 + 6H2O  C6H12O6 + 6O2 ΔG = +686 kcal/mol Therefore, every mole of Glucose has 686 kcal more energy than a mole of water and CO2 (oxygen doesn’t have any free energy to speak of as the electrons are held quite tightly).

  23. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Reverse an Endergonic Rx What do you get? ATP ADP + Pi (endergonic) reverse it ATP ADP + Pi (exergonic)

  24. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” What about if we reverse these reactions in terms of free energy? ADP + Pi ATP Dehydration synthesis of ATP ΔG = +7.3 kcal/mol You simply reverse the sign of ΔG since the products (ADP and P) will now have less available energy than the reactant (ATP). ATP  ADP + Pi Hydrolysis of ATP ΔG = -7.3 kcal/mol A -ΔG tells us that energy is lost and this reaction is exergonic and therefore SPONTANEOUS.

  25. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” Free Energy change (ΔG) YES No Negative (-) Positive (+) Products have less energy Products have more energy

  26. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. REVIEW

  27. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. What is the sign for ΔG in each case? ΔG is negative since both involve the release of energy and are spontaneous

  28. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. How is free energy change ΔG calculated? ΔG = ΔH – TΔS Entropy – the measure of disorder. Free Energy – the portion of an organism’s energy that can do work. Temperature – in Kelvin (formula assumes constant temperature) Enthalpy – a measure of heat energy.

  29. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” One must focus calculate two components…ΔH and ΔS, and know the temperature (T): ΔG = ΔH - TΔS ΔH = change in enthalpy or change in total internal energy over the course of the reaction. 1. You can think of it like “heat” a. A negative ΔH (-ΔH) means that “heat energy” is lost by the reactants Yes, energy being released - Would this promote a spontaneous reactions (-ΔG)? b. A positive ΔH (+ΔH) means that “heat energy” is gained by the reactants - Would this promote a spontaneous reactions (-ΔG)? No, requires energy

  30. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” ΔG = ΔH - TΔS ΔS = change in entropy (measure of disorder) over the course of the reaction. a. A positive ΔS (+ΔS) means that disorder is increased or the products are more disordered Yes - Would this promote a spontaneous reactions? b. A negative ΔS (-ΔS) means that disorder is decreased or the products are more ordered No - Would this promote a spontaneous reactions? Fig 8.5

  31. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • When the value of ΔG is negative then the system has lost free energy. • This is favored by cells • In order for ΔG to be negative the system must either: • give up enthalpy – lose heat – (H must decrease) • give up order (TΔS must increase – disorder is favored) • Both (H must decrease and S must increase) • Losing Free Energy is favored by the universe • - ΔG is “spontaneous” • +ΔG is “non-spontaneous”

  32. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”.

  33. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Free energy = measure of system stability • High G – unstable system • Low G – stable system • Change in G (ΔG) can drive work. • Max stability – equilibrium – G is lowest • Change from equilibrium has a +ΔG and is not favored in closed systems • However, living things are open systems and generally do not reach equilibrium • Systems naturally favor moving high ΔG to lower ΔG

  34. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Equilibrium & Metabolism • Reactions in closed systems usually reach equilibrium • Reactions in open systems usually do not • Cells harness these ‘downhill’ reactions to do work. • “Downhill” = exergonic • A cell that has reached metabolic equilibrium is DEAD

  35. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Cells can perform 3 kinds of work: • Mechanical: ex: cilia beating • Transport: ex: pumping substances • Chemical: ex: synthesis How does one get an endergonic process to occur? If something needs to lose energy, what kind of reaction will that be? An exergonic reaction. Therefore, an exergonic reaction will be required to make and endergonic reaction proceed.

  36. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. This is called: Energy Coupling • Energy coupling: energy released by an exergonic reaction in a cell will be used to power a “coupled” endergonic one

  37. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • ATP - AdenosineTriphosphate • 5-carbon sugar • Nitrogenous base: adenine • 3 identical functional groups Mutual repulsion creates high - ΔG

  38. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • ATP + H2O ADP + Pi • ΔG = -7.3 kcal/mol • ‘High’ energy bonds result from interactions between phosphate groups – compressed spring. • Creating ADP is an exergonic reaction: lowers free energy

  39. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Hydrolysis of ATP decreases ΔG and creates heat. • Enzymes couple ATP hydrolysis (an exergonic reaction) with endergonic reactions. • Inorganic phosphate is attached to another molecule • Creates an intermediate – more reactive

  40. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Exergonic reactions release the energy that power endergonic ones • Catabolism powers anabolism

  41. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • ATP Regeneration • ADP + Pi ATP + H2O • Energy comes from catabolism Protein synthesis, DNA synthesis, RNA synthesis, Active transport, etc (Cell respiration)

  42. Chapter 8 – An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. • Interesting facts: • Muscle cells regenerate 10 million molecules of ATP in 1 second. • Humans would use their body’s weight in ATP every day if it were not recyclable.

  43. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe chemical reactions in terms of “energy” What is the fate of the food you eat? 1. Cell Respiration (make fuel - transfer the energy) 2. Biosynthesis 3. Storage (exergonic) (endergonic)

  44. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe the structure/function of Enzymes. PROBLEM: 1. Exergonic reactions like hydrolysis of polymers into monomers are spontaneous, which means they will happen all by themselves without an input of energy. The problem is that they typically happen far too_______ to sustain life. SLOWLY It would take years for the food you eat to hydrolyze down to monomers without any assistance and it might hydrolyze improperly resulting in molecules you cannot use… 2. The desired chemical reaction may not be the reaction that occurs…

  45. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe chemical reactions in terms of “energy”. AIM: Describe the structure/function of Enzymes. What type of molecule is making all of these anabolic (endergonic) and catabolic (exergonic) reaction happen at a reasonable, life sustaining rate?

  46. Chapter 8 – An Introduction to Metabolism Chapter 8 - An Introduction to Metabolism AIM: Describe the structure and function of enzymes. AIM: Describe the structure/function of Enzymes. Enzymes 1. Biological protein catalysts (remember enzymes are proteins) 2. Speed up SPECIFIC reactions The reaction would have happened by itself, it just takes too long Enzymes orient the substrates properly for the proper reaction to occur in the proper amount of time…

  47. Chapter 8 – An Introduction to Metabolism AIM: Describe the structure and function of enzymes. • Activation Energy (Ea) • The energy needed to activate the reaction • Often occurs as heat, can be absorbed from reactants surroundings What does this figure depict? This barrier is a symbol of the activation energy needed. The beans need a bit of starter energy (activation energy) to get them over the barrier before they can fall… How do enzymes speed up reactions?

  48. Chapter 8 – An Introduction to Metabolism AIM: Describe the structure and function of enzymes. Enzymes lower the activation energy

  49. Chapter 8 – An Introduction to Metabolism AIM: Describe the structure and function of enzymes. Enzymes catalyze reactions by: • Providing proper orientation • Stressing bonds and creating transition states • Providing favorable microenvironments • Participating in reaction directly