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Chapter 6 Metabolism: Energy and Enzymes 6.1: Cells and the flow of energy Energy: the ability to do work or bring about change Energy: the ability to.

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Presentation on theme: "Chapter 6 Metabolism: Energy and Enzymes 6.1: Cells and the flow of energy Energy: the ability to do work or bring about change Energy: the ability to."— Presentation transcript:

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2 Chapter 6 Metabolism: Energy and Enzymes

3 6.1: Cells and the flow of energy Energy: the ability to do work or bring about change Energy: the ability to do work or bring about change –Organisms need a constant supply of energy to maintain organization and carry out metabolic activities –Flow of energy: fig. 6.1

4 Forms of Energy Kinetic: energy of motion (a ball rolling down a hill) Kinetic: energy of motion (a ball rolling down a hill) Potential: stored energy (the food we eat has potential energy) Potential: stored energy (the food we eat has potential energy) Chemical: chemical composition of substances makes them possess energy, such as lipids, carbs, etc. Chemical: chemical composition of substances makes them possess energy, such as lipids, carbs, etc. Mechanical: a type of kinetic in which an organism is using its chemical energy and converting it (ie. An organism walking) Mechanical: a type of kinetic in which an organism is using its chemical energy and converting it (ie. An organism walking)

5 Laws of Thermodynamics These two laws explain why energy flows in ecosystems and cells These two laws explain why energy flows in ecosystems and cells Energy starts from the sun, and flows, it does not cycle. Some of the suns energy is dissipated as heat but most of it is used by plants for photosynthesis and animals when they eat. Eventually all solar energy is dissipated as heat. Energy starts from the sun, and flows, it does not cycle. Some of the suns energy is dissipated as heat but most of it is used by plants for photosynthesis and animals when they eat. Eventually all solar energy is dissipated as heat.

6 First Law of Thermodynamics Law of conservation of energy: energy cannot be created or destroyed, only changed from one form or another Law of conservation of energy: energy cannot be created or destroyed, only changed from one form or another See picture on p. 102, solar energy being used by a plant to convert carbon dioxide and water into carbohydrates, and energy being lost as heat See picture on p. 102, solar energy being used by a plant to convert carbon dioxide and water into carbohydrates, and energy being lost as heat

7 Second Law of Thermodynamics Energy cannot be changed from one form to another without a loss of usable energy Energy cannot be changed from one form to another without a loss of usable energy See picture on p. 103, carbohydrates being used for muscle contraction and some of the energy being lost as heat See picture on p. 103, carbohydrates being used for muscle contraction and some of the energy being lost as heat

8 Cells and entropy Entropy: a relative amount of disorganization Entropy: a relative amount of disorganization Processes that occur in cells naturally tend to move toward entropy. Processes that occur in cells naturally tend to move toward entropy. See fig. 6.2 and consider the messy room analogy: a neat room is more organized but less stable than a messy room (its easier to mess up), while a messy room is more stable but less organized (harder to clean up) See fig. 6.2 and consider the messy room analogy: a neat room is more organized but less stable than a messy room (its easier to mess up), while a messy room is more stable but less organized (harder to clean up)

9 ENTROPY

10 6.2 Metabolic Reactions and Energy Transformations Metabolism: the sum of all chemical reactions that occur in the body Metabolism: the sum of all chemical reactions that occur in the body Reactants: substances in a chemical reaction that begin the reaction Reactants: substances in a chemical reaction that begin the reaction Products: the result of the reaction Products: the result of the reaction In the reaction on the right, circle the reactants and draw a square around the products Direct combination or synthesis, in which 2 or more chemical elements or compounds unite to form a more complex product: Direct combination or synthesis, in which 2 or more chemical elements or compounds unite to form a more complex product: Direct combination synthesis Direct combination synthesis N2 + 3 H2 2 NH NHNH

11 Free energy The amount of energy available, still free to do work, after a chemical reaction has occurred The amount of energy available, still free to do work, after a chemical reaction has occurred From Wikipedia, the Gibbs free energy ΔG equals the work exchanged by the system with its surroundings, less the work of the pressure forces, during a reversible transformation of the system from the same initial state to the same final state. From Wikipedia, the Gibbs free energy ΔG equals the work exchanged by the system with its surroundings, less the work of the pressure forces, during a reversible transformation of the system from the same initial state to the same final state.

12 Exergonic Reactions When there is a negative ΔG, therefore energy is released. When there is a negative ΔG, therefore energy is released. Cellular respiration is an exergonic reaction Cellular respiration is an exergonic reaction

13 Endergonic reaction The ones in which ΔG is positive and energy is absorbed The ones in which ΔG is positive and energy is absorbed Examples: protein synthesis, nerve conduction, muscle contraction Examples: protein synthesis, nerve conduction, muscle contraction

14 Adenosine Triphosphate (ATP) The common energy currency of cells, when cells require energy, they spend ATP The common energy currency of cells, when cells require energy, they spend ATP The more active an organism, the greater its demand for ATP The more active an organism, the greater its demand for ATP It is constantly being generated from ADP (adenosine diphosphate) and a molecule of inorganic phosphate It is constantly being generated from ADP (adenosine diphosphate) and a molecule of inorganic phosphate Glucose breakdown during cellular respiration provides the energy for the buildup of ATP in mitochondria Glucose breakdown during cellular respiration provides the energy for the buildup of ATP in mitochondria

15 Structure of ATP

16 Coupled Reactions When reactions are both exergonic and endergonic; energy is first released by an exergonic reaction and in turn used to drive an endergonic reaction When reactions are both exergonic and endergonic; energy is first released by an exergonic reaction and in turn used to drive an endergonic reaction See fig. 6.4: first ATP is broken down to get energy and then that energy is used in muscle contraction See fig. 6.4: first ATP is broken down to get energy and then that energy is used in muscle contraction

17 Functions of ATP Uses of ATP in living systems: Uses of ATP in living systems: –Chemical: ATP provides the cell energy to synthesize macromolecules –Transport: ATP provides energy for cells to transport molecules across membranes –Mechanical: enables muscle contraction, cells to move, cell division, etc….

18 For next time(MONDAY) We will finish ch. 6 notes We will finish ch. 6 notes READ chapter 6!!! READ chapter 6!!! On page 112 do reviewing ch. #1-7 On page 112 do reviewing ch. #1-7 Study session MON after school for one hour! Study session MON after school for one hour! TEST (chapters 2-6) TUES TEST (chapters 2-6) TUES Come tomorrow to randomly choose your take home essay, due TUES Come tomorrow to randomly choose your take home essay, due TUES


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