Presentation on theme: "Metabolism: Energy and Enzymes"— Presentation transcript:
1 Metabolism: Energy and Enzymes Chapter 6Metabolism: Energy and Enzymes
2 6.1: Cells and the flow of energy Energy: the ability to do work or bring about changeOrganisms need a constant supply of energy to maintain organization and carry out metabolic activitiesFlow of energy: fig. 6.1
3 Forms of Energy Kinetic: energy of motion (a ball rolling down a hill) Potential: stored energy (the food we eat has potential energy)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 it’s chemical energy and converting it (ie. An organism walking)
4 Laws of Thermodynamics These two laws explain why energy flows in ecosystems and cellsEnergy starts from the sun, and flows, it does not cycle. Some of the sun’s 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.
5 First Law of Thermodynamics Law of conservation of energy: energy cannot be created or destroyed, only changed from one form or anotherSee 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
6 Second Law of Thermodynamics Energy cannot be changed from one form to another without a loss of usable energySee picture on p. 103, carbohydrates being used for muscle contraction and some of the energy being lost as heat
7 Cells and entropy Entropy: a relative amount of disorganization 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 (it’s easier to mess up), while a messy room is more stable but less organized (harder to clean up)
9 6.2 Metabolic Reactions and Energy Transformations Metabolism: the sum of all chemical reactions that occur in the bodyReactants: substances in a chemical reaction that begin the reactionProducts: the result of the reactionIn the reaction on the right, circle the reactants and draw a square around the productsDirect combination or synthesis, in which 2 or more chemical elements or compounds unite to form a more complex product:N2 + 3 H2 → 2 NH
10 Free energyThe amount of energy available, still ‘free’ to do work, after a chemical reaction has occurredFrom 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.“
11 Exergonic ReactionsWhen there is a negative ΔG, therefore energy is released.Cellular respiration is an exergonic reaction
12 Endergonic reactionThe ones in which ΔG is positive and energy is absorbedExamples: protein synthesis, nerve conduction, muscle contraction
13 Adenosine Triphosphate (ATP) The common energy currency of cells, when cells require energy, they ‘spend’ ATPThe more active an organism, the greater its demand for ATPIt is constantly being generated from ADP (adenosine diphosphate) and a molecule of inorganic phosphateGlucose breakdown during cellular respiration provides the energy for the buildup of ATP in mitochondria
15 Coupled ReactionsWhen reactions are both exergonic and endergonic; energy is first released by an exergonic reaction and in turn used to drive an endergonic reactionSee fig. 6.4: first ATP is broken down to get energy and then that energy is used in muscle contraction
16 Functions of ATP Uses of ATP in living systems: Chemical: ATP provides the cell energy to synthesize macromoleculesTransport: ATP provides energy for cells to transport molecules across membranesMechanical: enables muscle contraction, cells to move, cell division, etc….
17 For next time(MONDAY) We will finish ch. 6 notes READ chapter 6!!! On page 112 do ‘reviewing ch. #1-7Study session MON after school for one hour!TEST (chapters 2-6) TUESCome tomorrow to randomly choose your take home essay, due TUES