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Metabolism: Energy in Life Processes

Explore the chemical reactions involved in metabolism, from catabolic pathways releasing energy to anabolic pathways building molecules. Discover how energy transformations follow thermodynamic laws, and the crucial role of ATP and enzymes in cellular activities. Unravel the concepts of free energy, activation energy, and the control mechanisms of metabolism to appreciate the complexities of life processes.

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Metabolism: Energy in Life Processes

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  1. Chapter 8 An Introduction To Metabolism

  2. Metabolism • All the chemical reactions in an organism • Concerned with managing the matter and energy resources of the organism.

  3. Catabolic Pathways • Pathways that break down complex molecules into smaller ones, releasing energy. • Example: Cellular Respiration

  4. Anabolic Pathways • Pathways that consume energy, building complex molecules from smaller ones. • Example: Photosynthesis

  5. Anabolic vs Catabolic

  6. Energy • Ability to do work. • The ability to rearrange a collection of matter. • Forms of energy: • Kinetic • Potential • Activation

  7. Kinetic Energy • Energy of action or motion.

  8. Potential Energy • Stored energy • Can be in chemical bonds!

  9. Activation Energy • Energy needed to convert potential energy into kinetic energy. Activation Energy Potential Energy

  10. Energy Transformation • Governed by the Laws of Thermodynamics.

  11. 1st Law of Thermodynamics • Energy can be transferred and transformed, but it CANNOT be created or destroyed. • Also known as the law of “Conservation of Energy”

  12. 2nd Law of Thermodynamics • Each energy transfer or transformation increases the entropy of the universe.

  13. Entropy • Measure of disorder. • High entropy = high disorder

  14. Free Energy Changes

  15. Question? • How does Life go against Entropy? • By using energy from the environment or external sources (e.g. food, light).

  16. Summary • The quantity of energy in the universe is constant, but its quality is not.

  17. Gibbs Free Energy • Free energy = The portion of a system's energy that can perform work. • “usable energy”

  18. Free Energy of a reaction ΔG = ΔH – TΔS Δ = Change (final – initial) G = free energy of a system H = enthalpy = total energy of a system T = temperature in oK S = entropy of a system

  19. Reactions will move from unstable states to stable states

  20. Free Energy Changes

  21. Reaction Types • Exergonic: chemical reactions with a net release of free energy. • ΔG = NEGATIVE VALUE • Spontaneous • catabolic • Endergonic: chemical reactions that require free energy from the surroundings. • ΔG = POSITIVE VALUE • Spontaneous • Anabolic

  22. Biological Examples • Exergonic - respiration • Endergonic - photosynthesis

  23. How does the cell perform endergonic reactions? • Couples an exergonic process to drive an endergonic one. • ATP is used to couple the reactions together.

  24. ATP • Adenosine Triphosphate • Made of: - Adenine (nitrogenous base) - Ribose (pentose sugar) - 3 phosphate groups

  25. Adenine Phosphates Ribose

  26. Key to ATP • Is in the three phosphate groups. • Negative charges repel each other and makes the phosphates unstable.

  27. ATP • Works by energizing other molecules by transferring phosphate groups.

  28. ATP vs Food • ATP: • Renewable energy resource. • Unstable bonds • Food: • Long term energy storage • Stable bonds

  29. ATP Cycles • Energy released from ATP drives endergonic reactions. • Energy from exergonic reactions “recharges” ATP.

  30. ATP in Cells • A cell's ATP content is recycled every minute. • Humans use close to their body weight in ATP daily. • No ATP production equals quick death.

  31. Enzymes • Biological catalysts made of protein. • Cause the rate of a chemical reaction to increase.

  32. Enzymes • Lower the activation energy for a chemical reaction to take place.

  33. free energy

  34. Enzyme Terms • Substrate - the material and enzyme works on. • Enzyme names: Ex. Sucrase - ase name of an enzyme 1st part tells what the substrate is. (Sucrose)

  35. Control of Metabolism • Is necessary if life is to function. • Controlled by switching enzyme activity "off" or "on” or separating the enzymes in time or space.

  36. Structural Order • Separation of enzymes and metabolic pathways in time or space by the cell's organization. • Example: enzymes of respiration

  37. Summary • Recognize that Life must follow the Laws of Thermodynamics. • The role of ATP in cell energy. • How enzymes work.

  38. Cellular Respiration and Photosynthesis • You will need to know the inputs and outputs of each reaction • Where is each reaction taking place • Understand what the “goal” of each reaction is • What is the role of the major molecules • Connect back to previous material (facilitated diffusion, active transport, exergonic, endergonic)

  39. Rs - Equation C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP The energy is released from the chemical bonds in the complex organic molecules.

  40. Oxidation - definitions • Loss of electrons. • Loss of energy.

  41. Reduction - definitions • Gain of electrons. • Gain of energy.

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