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An Organism’s Metabolism Transforms Matter and Energy, Subject to the Laws of Thermodynamics

An Organism’s Metabolism Transforms Matter and Energy, Subject to the Laws of Thermodynamics. Potential and Kinetic Energy : Cheetah at Rest and Running. Energy is lost as heat. Potential and Kinetic Energy :.

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An Organism’s Metabolism Transforms Matter and Energy, Subject to the Laws of Thermodynamics

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  1. An Organism’s Metabolism Transforms Matter and Energy, Subject to the Laws of Thermodynamics

  2. Potential and Kinetic Energy: Cheetah at Rest and Running Energy is lost as heat

  3. Potential and Kinetic Energy:

  4. First Law of Thermodynamics: Energy Can Neither Be Created or DestroyedSecond Law of Thermodynamics: Every Energy Transfer Increases the Disorder (Entropy) of the Universe.

  5. The Free Energy Change of a Reaction Tells Us Whether the Reaction Occurs Spontaneously ∆G = G Final State – G Initial State

  6. The Relationship of Free Energy to Stability, Work Capacity, and Spontaneous Change

  7. Energy Changes in Exergonic (energy releasing) and Endergonic (energy storing) Reactions

  8. Disequilibrium and Work in Closed and Open Systems

  9. (b) An open hydroelectric system. Flowing water keeps driving the generator because intake and outflow of water keep the system from reaching equilibrium. ∆G < 0 Figure 8.7 • Cells in our body experience a constant flow of materials in and out, preventing metabolic pathways from reaching equilibrium

  10. ATP powers cellular work by coupling exergonic reactions to endergonic reactions • A cell does three main kinds of work: • Mechanical • Transport • Chemical

  11. Adenosine triphosphate (ATP) is a kind of “energy currency” in cells. Energy released by exergonic reactions is stored in the bonds of ATP. When ATP is hydrolyzed, free energy is released to drive endergonic reactions.

  12. P i P Motor protein Protein moved (a) Mechanical work: ATP phosphorylates motor proteins Membrane protein ADP + ATP P i P P i Solute Solute transported (b) Transport work: ATP phosphorylates transport proteins P NH2 + + NH3 P i Glu Glu Reactants: Glutamic acid and ammonia Product (glutamine) made Figure 8.11 (c) Chemical work: ATP phosphorylates key reactants • The three types of cellular work are powered by the hydrolysis of ATP

  13. The Structure and Hydrolysis of ATP

  14. Energy COUPLING by Phosphate Transfer

  15. ATP synthesis from ADP + P i requires energy ATP hydrolysis to ADP + P i yields energy ATP Energy from catabolism (exergonic, energy yielding processes) Energy for cellular work (endergonic, energy- consuming processes) ADP + P i Figure 8.12 The Regeneration of ATP • Catabolic pathways drive the regeneration of ATP from ADP and phosphate

  16. An active cell needs millions of molecules of ATP per second to drive its biochemical machinery. They’re consumed in less than a second and an average person produces and hydrolyzes about 40 kg of ATP per day!

  17. Enzymes 1.Proteins: most enzymes are catalytic proteins, primarilytertiaryandquaternary structures. 2.Catalysts:chemical agents that accelerate a reaction without being permanently changed in the process.

  18. Enzymes speed up metabolic reactions by lowering energy barriers

  19. Substrate Enzyme Active Site Active Site • A restricted regionof an enzyme molecule which binds to the substrate.

  20. The Active Site • Most enzyme-substrate interactions are the result of weak bonds. • The active site may cause the enzyme to hold onto the substrate in a very specific way and create a micro environment (specific pH) forming an enzyme-substrate complex.

  21. Enzyme / Substrate Relationship: • What is the substrate? • It is the reactant upon which an enzyme reacts. • Enzymes are substrate specific. • Only the active site of the enzyme actually binds the substrate.

  22. Enzyme Substrate Substrate • The substance (reactant) an enzyme acts on.

  23. Example of an Enzyme-Catalyzed Reaction: Hydrolysis of Sucrose

  24. How Do Reactions Occur? • Spontaneous reactions may occur very slowly. • All reactions require free energy of activation (EA) • Uphill portion represents the EA required to start the reaction. • Downhill portion represents the loss of free energy by the molecules in the reaction.

  25. Is this reaction exergonic or endergonic?

  26. How can the EA barrier be overcome? • Temperature • Temperatures that are too high denature (break apart) organic molecules, so what else is there? • Enzymes lower the EA barrier so that reactions can occur at lower temperatures.

  27. Without Enzyme With Enzyme Free Energy Free energy of activation Reactants Products Progress of the reaction Enzymes

  28. Temperature pH Enzyme Concentration Substrate Concentration Enzyme Activity is Affected by:

  29. Enzyme Animations https://www.youtube.com/watch?v=qgVFkRn8f10&vl=en https://www.youtube.com/watch?v=H_1ULIKzwfA http://www.wiley.com/college/test/0471787159/biology_basics/animations/howEnzymesWork.html http://www.cengage.com/biology/discipline_content/animations/enzyme_role_m.html http://bcs.whfreeman.com/webpub/Ektron/pol1e/Animated%20Tutorials/at0302/at_0302_enzyme_catalysis.html

  30. Active Site substrate Enzyme induced fit Induced Fit • Achange in the configuration of an enzyme’sactive site(H and ionic bonds are involved). • Induced by the substrate.

  31. substrate (sucrose) + enzyme (sucrase)  enzyme-substrate complex  products + enzyme and + sucrase glucosefructose Enzymatic Reaction

  32. Cofactors and Coenzymes • Inorganic substances (zinc, iron) and vitamins (respectively) are sometimes needed for proper enzymatic activity. • Example: Iron must be present in the quaternary structure-hemoglobin in order for it to pick up oxygen.

  33. Substrate Enzyme Competitive inhibitor Enzyme Inhibitors • Two examples: a. Competitive Inhibitors: are chemicals that resemble an enzyme’s normal substrateand compete with it for the active site.

  34. Noncompetitive Inhibitor Substrate Enzyme active site altered Enzyme Inhibitors b. Noncompetitive Inhibitors: Inhibitors that do not enter the active site, but bind to another partof the enzyme causing the enzyme to change its shape, which in turn alters the active site.

  35. Allosteric Regulation • Regulatory molecules that bind to the enzyme’s allosteric site changing the shape of the enzyme. • Allosterically regulated enzymes have a quaternary protein structure. • Each subunit of the enzyme has an active site and an allosteric site. • Allosteric activators stabilize the active site • Allosteric inhibitors deactivate the active site.

  36. Feedback Inhibition A metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme earlier in the pathway

  37. In the amylase lab, the • amylase broke down the polysac- • charides (starches) into _______. • 2) Enzymes work by lowering • the ___________ _________ • required for a reaction to occur.

  38. What part of the enzyme comes in contact with the substrate? If the disaccharide lactose is broken down, _________ is the enzyme, and the products are __________ and ___________.

  39. If the active site of the enzyme is blocked by another molecule this is called: What happens if another molecule that has a similar shape as the enzyme is in a higher quantity in the cell?

  40. Draw pictures showing the action of an enzyme. Label the enzyme, the active site, substrate, and the products after the reaction has taken place.

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