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Energy and Enzymes

Energy and Enzymes. Energy in Living Systems. Energy is the capacity to perform work Energy can be converted from one form to another. Energy in Living Systems. KINETIC ENERGY is the energy of motion Includes light Includes heat. Energy in Living Systems.

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Energy and Enzymes

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  1. Energy and Enzymes

  2. Energy in Living Systems • Energy is the capacity to perform work • Energy can be converted from one form to another

  3. Energy in Living Systems • KINETIC ENERGY is the energy of motion • Includes light • Includes heat

  4. Energy in Living Systems • POTENTIAL ENERGY is the energy stored in a location or structure

  5. Energy in Living Systems • POTENTIAL ENERGY is the energy stored in a location or structure • Molecules have potential energy called CHEMICAL ENERGY

  6. Energy in Living Systems • Cells convert KINETIC ENERGY to POTENTIAL ENERGY and back.

  7. Thermodynamics • 1st law: Energy can be changed from one form to another, but cannot be created or destroyed.

  8. Thermodynamics • 2nd law: Energy transformations increase disorder, or entropy, and some energy is lost as heat

  9. Laws of Thermodynamics in Organisms Heat • As energy is converted from one form to another, heat is lost Chemical reactions Carbon dioxide Glucose ATP ATP Water Oxygen Energy for cellular work

  10. Energy Flow Through Ecosystems • Energy flows in one direction through ecosystem

  11. Majority of Energy is from the SUN • Amount of energy captured by plants influences the ecosystem

  12. Energy Capture • Energy flow: Sun  producers  consumers  decomposers and Bacteria

  13. Energy Flow Through Ecosystems • Two ways for organisms to capture energy • Producers - produce chemical energy from energy in sunlight

  14. Energy Flow Through Ecosystems • Two ways for organisms to capture energy • Producers - produce chemical energy from energy in sunlight • Consumers - consume other organisms for energy

  15. Food webs - the reality **Arrows show energy flow, not who eats who

  16. Food web creation • http://www.gould.edu.au/foodwebs/kids_web.htm

  17. Energy Pyramid • Energy flows through food chain • Most energy lost as metabolic heat • Each step is a trophic level

  18. Concentration of toxins • As you go up the energy pyramid, toxins build up in bodies of animals • “Bioaccumulation” and “biomagnification” • Example: DDT • Example: Mercury

  19. Energy in Living Systems • Metabolismis the sum of all chemical reactions in the body. • Characteristic of Living Things • Transfers energy and follows the laws of thermodynamics. • Chemical Reactions store or release energy

  20. Chemical Reactions • Reactants interact, leading to products • Atoms are rearranged, but the number of atoms stays constant on both sides of the equation H2 + O2 H2O PRODUCT REACTANTS

  21. Chemical reactions 2 H2 + O2  2 H2O H H H H O O REACTANTS? PRODUCTS? H H H H O O

  22. Chemical reactions 3 H2 + N2  2 NH3 H H N N N N H H H H REACTANTS? PRODUCTS? H H H H H H

  23. Types of Chemical Reactions Products ENDERGONIC • Require an input of energy from the surroundings • Yield products rich in potential energy • Example: photosynthesis Amount of energy required Energy required Potential energy of molecules Reactants

  24. Types of Chemical Reactions Reactants EXERGONIC • Release energy • Yield products that contain less potential energy than their reactants • Examples: cellular respiration, burning Amount of energy released Energy released Potential energy of molecules Products

  25. Using Energy from Food • Energy transfer in cells must be controlled • Reactions are carefully controlled

  26. Uncontrolled Reaction • Glucose and Oxygen react when exposed to a spark • Energy is released all at once • CO2 and H2O form

  27. Controlled Reaction CO2 e– glucose • Energy input used to split glucose • Same overall reaction occurs, but in small steps • Energy can be harnessed to do work in cell • CO2 and H2O form oxygen H+ e– water

  28. Enzymes • Proteins • Perform and control chemical reactions • Why are enzymes important? • Digestion • Building / recycling cells • Muscle contraction • Everything that happens in your body

  29. Enzymes

  30. Enzyme Examples • Lactase – cleaves lactose sugar • DNA Polymerase – joins nucleotide monomers to make DNA polymer • Luciferase – generates light in fireflies • Amylase – breaks down starch during digestion • Protease – breaks down proteins • Cellulase – breaks down cellulose (bacterial enzyme found in ruminants)

  31. Interesting Enzyme Example • A Hope For Oil Spill Bioremediation ScienceDaily (May 17, 2005) — A recently published article in Environmental Microbiology reveals that indigenous microbiota of the Galician shore is readily able to degrade crude oil. • What are the consequences of this discovery?

  32. Enzymes • “Catalysts” • speed up a reaction, but aren’t used up • Can be used over and over in the cell

  33. Enzymes • Enzymes are not altered in a reaction and can be used again (catalyst) • “A catalyst for change” • Lew-Port Enzyme Animation

  34. Reactions and Enzymes Some chemical reactions need a “jump start” in order to proceed Energy needed to jump start a reaction is called activation energy

  35. Reactions and Enzymes • Glucose contains energy in its bonds • Energy is released when bonds are broken • Small amount of energy must be expended to start reaction

  36. Enzymes substrate products “Gets turned into” Chemical Reaction Catalyzed by enzyme Work by lowering the activation energy. Reactants the enzyme acts upon are called substrates. H2O2H2O+ O2

  37. Activation Energy EAwithout enzyme EAwith enzyme Reactants Energy Net change in energy Products Progress of the reaction

  38. Where does the energy come from? • ATP is a form of chemical energy the cell can use • ATP (adenosine triphosphate) powers nearly all forms of cellular work

  39. Where does the energy come from? • ATP is composed of one adenine, one ribose, and three negatively charged phosphates • The energy in an ATP molecule lies in the bonds between its phosphate groups

  40. How does ATP work? Adenosine Triphosphate Adenosine diphosphate Phosphate group H2O P P P P P + P + Energy Hydrolysis Adenine Ribose ADP ATP

  41. How does ATP work? Adenosine Triphosphate Adenosine diphosphate Phosphate group H2O P P P P P + P + Energy Hydrolysis Adenine Ribose ADP ATP

  42. How does ATP work? • ATP powers cellular work through coupled reactions • The bonds connecting the phosphate groups are broken by hydrolysis, an exergonic reaction (absorbs or releases energy?) • Hydrolysis is coupled to an endergonic reaction through phosphorylation • A phosphate group is transferred from ATP to another molecule

  43. ATP Chemical work Mechanical work Transport work Membrane protein Solute P Motor protein P Reactants P P P Product P Solute transported Protein moved Molecule formed ADP  P

  44. ATP regenerates ATP • The ATP cycle involves continual phosphorylation and hydrolysis Phosphoylation Hydrolysis Energy from exergonic reactions Energy for endergonic reactions ADP + P

  45. Enzymes • Very specific for reactions • Three dimensional shape determines function (remember the World’s Largest Protein) • Active site is region where the substrate binds

  46. “Lock and Key” • Easy version: Enzyme and substrate fit like a lock and key (shape)

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