Metabolism: Energy And Enzymes - Welcome To Biology!
Chapter 6 Metabolism: Energy and Enzymes 1 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
6.1 Life and the Flow of Energy Energy is the ability to do work or bring about change Cells (and organisms) need a constant supply of energy Life on Earth is dependent on solar energy – Photosynthesis provides nutrients
6.1 Life and the Flow of Energy Forms of Energy – Kinetic energy is the energy of motion – Potential energy is stored energy Food is chemical energy
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Solar energy heat heat Chemical energy heat Mechanical energy
6.1 Life and the Flow of Energy Two Laws of Thermodynamics 1. Energy cannot be created or destroyed, but it can be changed from one form to another Law of conservation of energy 2. Energy cannot be changed from one form to another without a loss of usable energy
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. heat CO2 sun H2O Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. solar energy carbohydrate synthesis heat carbohydrate muscle contraction A leaf cell photosynthesizes – Use solar energy to form carbohydrates – Some energy is lost as heat Moose uses carbohydrates to power its muscles – Some energy is lost as heat
6.1 Life and the Flow of Energy The second law of thermodynamics can be stated another way Every energy transformation makes the universe less organized and more disordered Entropy refers to the relative amount of disorganization
6.1 Life and the Flow of Energy Every process that occurs in cells always does so in a way that increases the total entropy of the universe Cellular processes obviously require an input of energy from an outside source Living things depend on a constant supply of energy from the sun
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. energy H2O C6H12O6 CO2 Glucose more organized more potential energy less stable (less entropy) a. Carbon dioxide and water less organized less potential energy more stable (more entropy)
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. channel protein H H H H H H Unequal distribution of hydrogen ions more organized more potential energy less stable (less entropy) b. H H H H H energy H H H H H H H Equal distribution of hydrogen ions less organized less potential energy more stable (more entropy)
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H2O energy C6H12O6 CO2 Glucose more organized more potential energy less stable (less entropy) Carbon dioxide and water less organized less potential energy more stable (more entropy) a. H H H H H H Unequal distribution of hydrogen ions more organized more potential energy less stable (less entropy) b. H H H H H energy H H H channel protein H H H H Equal distribution of hydrogen ions less organized less potential energy more stable (more entropy)
6.2 Energy Transformations and Metabolism Metabolism is the sum of all the chemical reactions that occur in a cell Catabolism – breaking down molecules Anabolism – building molecules
6.2 Energy Transformations and Metabolism A B (reactants) C D (products)
6.2 Energy Transformations and Metabolism Free energy ( G) is the amount of energy available. – Exergonic reactions are ones where energy is released ( G is negative) Products have less free energy than reactants – Endergonic reactions require an input of energy ( G is positive) Products have more free energy than reactants
6.2 Energy Transformations and Metabolism Exergonic reactions – Spontaneous – Release energy Endergonic – Require an input of energy to run – Require ATP
6.2 Energy Transformations and Metabolism ATP stands for adenosine triphosphate – Energy currency for cells – ATP is generated from ADP (adenosine diphosphate) an inorganic phosphate molecule ( P )
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. adenosine triphosphate P Energy from exergonic reactions (e.g., cellular respiration) P ATP ADP Energy for endergonic reactions (e.g., protein synthesis, nerve impulse conduction, muscle cont r action) P P adenosine diphosphate a. P P P phosphate
6.2 Energy Transformations and Metabolism ATP is a nucleotide composed of: – Adenine (a nitrogen-containing base) – Ribose (a 5-carbon sugar) – Three phosphate groups Energy stored in these chemical bonds
6.2 Energy Transformations and Metabolism Coupled Reactions – The energy released by an exergonic reaction is used to drive an endergonic reaction Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP ADP A B C D coupling P
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP ADP P a. ATP breakdown is exergonic. energy b. Muscle contraction is endergonic and cannot occur without an input of energy.
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. heat ATP ADP P muscle contraction c. Muscle contraction becomes exergonic and can occur when it is coupled to ATP breakdown.
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. ATP ADP P energy heat ATP ADP P a. ATP breakdown is exergonic. muscle contraction c. Muscle contraction becomes exergonic and can occur when it is coupled to ATP breakdown. b. Muscle contraction is endergonic and cannot occur without an input of energy.
6.2 Energy Transformations and Metabolism ATP can be used for – Chemical work Powers anabolism – Transport work Supplies energy to pump substances across plasma membrane – Mechanical work Supplies energy to make muscles contract, cilia and flagella beat
6.3 Enzymes and Metabolic Pathways Metabolic pathways are a series of linked reactions. – These begin with a specific reactant and produce an end product
6.3 Enzymes and Metabolic Pathways Enzymes – Proteins that function to speed a chemical reaction – Enzymes serve as catalysts Participates in chemical reaction, but is not used up by the reaction
A Metabolic Pathway Also called substrates
6.3 Enzymes and Metabolic Pathways Energy of Activation (Ea) – Energy that must be added to cause molecules to react with one another Need a match to start wood burning – Enzymes lower the energy of activation Do not change the end result of the reaction Increase the reaction rate
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. energy of activation (Ea) energy of reactant Free Energy energy of activation (Ea) energy of product enzyme not present enzyme present Progress of the Reaction
6.3 Enzymes and Metabolic Pathways How Enzymes Function – Enzyme binds substrate to form a complex E S ES E P enzyme substrate enzyme-substrate complex enzyme product
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. products enzyme substrate enzyme-substrate complex active site Degradation The substrate is broken down to smaller products. enzyme Substrate binds to active site on enzyme
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. product enzyme substrates enzyme-substrate complex active site Synthesis The substrates are combined to produce a larger product. enzyme
6.3 Enzymes and Metabolic Pathways Induced fit model – Substrate and active site shapes don’t match exactly – Active site is induced to undergo a slight change in shape to accommodate substrate binding – Change in shape facilitates reaction
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. active site a. substrate b.
6.3 Enzymes and Metabolic Pathways Reaction requires specific enzyme Enzymes often named for their substrate – Lipid – lipase – Urea – urease – Maltose – maltase – Lactose – lactase
6.3 Enzymes and Metabolic Pathways Factors affecting enzymatic reaction rates – Substrate Concentration – Temperature and pH – Enzyme Activation – Enzyme Inhibition – Enzyme Cofactors
6.3 Enzymes and Metabolic Pathways Substrate Concentration – Enzyme activity increases as substrate concentration increases More collisions between substrate and enzyme – Maximum rate is achieved when all active sites of an enzyme are filled continuously with substrate
6.3 Enzymes and Metabolic Pathways Temperature – Enzyme activity increases as temperature rises – Higher temperatures cause more effective collisions between enzymes and substrates – Enzyme may denature at high temperatures Loss of structure and function
Rate of Reaction (product per unit of time) Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 0 10 20 30 40 50 60 Temperature C a. Rate of reaction as a function of temperature. b. Body temperature of ectothermic animals often limits rates of reactions. c. Body temperature of endothermic animals promotes rates of reactions. b: Brand X Pictures/PunchStock RF; c: Digital Vision/PunchStock RF
6.3 Enzymes and Metabolic Pathways pH – Each enzyme has an optimal pH – Enzyme structure is pH dependent – Extremes of pH can denature an enzyme by altering its structure
Rate of Reaction (product per unit of time) Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. pepsin 0 1 2 3 trypsin 4 5 6 pH 7 8 9 10 11 12
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. P P kinase inactive protein active protein Enzyme Activation – Cell regulates metabolism by regulating which enzymes are active – Genes producing enzymes can be turned on or off to regulate enzyme concentration – Enzyme can be modified by adding or removing phosphates – changes shape
6.3 Enzymes and Metabolic Pathways Enzyme Inhibition – Occurs when enzyme cannot bind its substrate – Activity of almost every cell enzyme is regulated by feedback inhibition
6.3 Enzymes and Metabolic Pathways Enzyme Inhibition – When product is abundant it binds to the enzyme’s active site and blocks further production When product is used up, it is removed from the active site Enzyme begins to function again
6.3 Enzymes and Metabolic Pathways Enzyme Inhibition – In a more complex type of inhibition, product binds to a site other than the active site, which changes the shape of the active site – Poisons are often enzyme inhibitors Cyanide inhibits an essential enzyme Penicillin blocks the active site on a bacterial enzyme
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. first reactant A site of enzyme where end product F can bind E1 E2 A a. Active pathway B E3 C E4 D E5 E end product F
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. altered site of enzyme due to binding of F first reactant A b. Inactive pathway E1 end product F E1 end product F Reactant A cannot bind, and no product results.
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. first reactant A site of enzyme where end product F can bind E1 E2 A B E3 C E4 D E5 E end product F a. Active pathway altered site of enzyme due to binding of F first reactant A b. Inactive pathway E1 end product F E1 end product F Reactant A cannot bind, and no product results.
6.3 Enzymes and Metabolic Pathways Enzyme Cofactors – Molecules which help enzyme function – Copper and zinc are examples of inorganic cofactors – Organic non-protein cofactors are called coenzymes Vitamins are often components of coenzymes
6.4 Oxidation-Reduction and Metabolism Oxidation-Reduction or Redox – Oxidation is the loss of electrons – Reduction is the gain of electrons – Ex: when oxygen combines with Mg Oxygen gains electrons – becomes reduced Mg loses electrons – becomes oxidized
6.4 Oxidation-Reduction and Metabolism Oxidation-Reduction – The term oxidation is used even when oxygen is not involved – Ex: Na Cl- NaCl Sodium is oxidized Chlorine is reduced
6.4 Oxidation-Reduction and Metabolism Oxidation-Reduction – Also applies to covalent reactions involving hydrogen atoms (e- H ) – Oxidation is the loss of hydrogen atoms Loss of electrons – Reduction is the gain of hydrogen atoms Gain of electrons
6.4 Oxidation-Reduction and Metabolism Photosynthesis – Energy 6CO2 6H2O C6H12O6 6O2 – Hydrogen atoms are transferred from water to carbon dioxide and glucose is formed – Energy is required and this comes in the form of light energy from the sun – Chloroplasts convert solar energy to ATP which is then used along with hydrogen to reduce carbon dioxide to glucose
6.4 Oxidation-Reduction and Metabolism Cell Respiration – C6H12O6 6O2 6CO2 6H2O energy – Glucose is oxidized (lost hydrogen atoms) – Oxygen is reduced to form water (gained hydrogen atoms) – Energy produced is used to form ATP – The oxidation of glucose to form ATP is done in a series of small steps to increase efficiency
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Photosynthesis Cellular respiration carbohydrate sun O2 chloroplast mitochondrion heat heat CO2 HO2 ATP for synthetic reactions, active transport, muscle contraction, nerve impulse heat (leaves): Comstock/PunchStock RF; (runner): PhotoDisc/Getty RF
6.4 Oxidation-Reduction and Metabolism Human beings are involved in the cycling of molecules between chloroplasts and mitochondria Our food is derived from plants or we eat animals that have eaten plants Food nutrients and oxygen enter our mitochondria to produce ATP
Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. O2 CO2 Breathing Eating O2 CO2 Nutrients ATP Cellular respiration Getty Images/SW Productions RF
6.4 Oxidation-Reduction and Metabolism Your diet is not all glucose Our food consists of carbohydrates, fats, and proteins Broken down into simpler molecules in digestion Can enter cellular respiration at various steps in the pathway to make ATP Excess glucose can be used to form fatty acids – Fatty acids and glycerol form lipids or fat
6.2 Energy Transformations and Metabolism Free energy ( G) is the amount of energy available. -Exergonic reactions are ones where energy is released ( G is negative) Products have less free energy than reactants -Endergonic reactions require an input of energy ( G is positive) Products have more free energy than reactants
metabolism? We can group enzymes together according to the types of reactions they catalyse. –Hydrolase enzymes control hydrolysis reactions. –Oxidoreductase enzymes control redox reactions. –Transferase enzymes move whole chemical groups (eg. methyl, amino, carboxyl). –Isomerase enzymes change the shape of a molecule (creating an .
Restriction enzymes and DNA ligases represent the cutting and joining functions in DNA manipulation. All other enzymes involved in genetic engineering fall under the broad category of enzymes known as DNA modifying enzymes. These enzymes are involved in the degradation, synthesis and alteration of the nucle
A) Metabolism depends on a constant supply of energy from food B) Metabolism depends on an organismʹs adequate hydration C) Metabolism utilizes all of an organismʹs resources D) Metabolism is a property of organismal life E) Metabolism manages the increase of entropy in an organism Answer: D Topic: Concepts 8.1, 8.5
Metabolism: Collective term referring to catabolism and anabolism combined. Enzymes: Protein catalysts that facilitate reactions by lowering the activation energy (E A) required for the reaction to take place. Enzymes also facilitate reactions by keeping reagents close to one another.
4 CHARACTERISTICS of Enzymes – 1. Enzymes do not make anything happen that couldn’t happen on its own, just makes it happen faster. 2. Enzymes are not used up in reactions. They can be used over and over again! 3. Enzymes are highly specific: each enzyme catalyzes a specific chemical rea
Enzymes in Organic Chemistry! March 25th, 2013! Enzymes Enzymes are biological catalysts. They increase the rate at which equilibrium is reached, but they do not affect the equilibrium. Enzymes differ from ordinary chemical catalyst
Organisms use protein catalysts called enzymes to accelerate many metabolic reactions to useful rates. Enzymes are mainly made of proteins, although many enzymes also incorporate non-protein cofactors, such as vitamins or metals. Enzymes lower the Ea of a reaction because substrates bind to a specific
100 Days of School, 100 Agricultural Activities! 100th Day festivities have been celebrated throughout schools since the school year of 1981-1982. Lynn Taylor introduced the 100th Day of School idea in the Center for Innovation in Education newsletter. Early celebrations focused on developing number sense for young children. Today, preschool children through elementary students celebrate their .
