Chapter 6: Energy Flow In The Life Of A Cell

Chapter 6:Energy Flow in the Life of a Cell

Chapter 6: Energy Flow in CellsWhat is Energy?Answer: The Capacity to do WorkTypes of Energy:1) Kinetic Energy Energy of movement Light (movement of photons) Heat (movement of particles) Electricity (movement of charged particles)2) Potential Energy Stored energy Chemical (stored in bonds) Electrical (stored in battery) Positional (stored in location of object)

Chapter 6: Energy Flow in CellsPotential energy can be converted to kinetic energy (& vice versa)Potential EnergyKinetic Energy

Chapter 6: Energy Flow in CellsLaws of Thermodynamics: Explain the properties and behaviorof energy1st Law of Thermodynamics: Amount of energy in universe remains constant Energy is neither created or destroyed Law of Conservation of Energy Energy can be converted (Chemical Heat)2nd Law of Thermodynamics: When energy converted, the amount of usefulenergy decreases No process is 100% efficient

Chapter 6: Energy Flow in CellsThe Laws of Thermodynamics in Action:

Chapter 6: Energy Flow in CellsChemical Reaction: Process that forms and breaks chemical bondsholding molecules together ReactantsProductsTwo Types of Chemical Reactions:1) Exergonic Reaction liberates energy2) Endergonic Reaction requires energy to proceed

Chapter 6: Energy Flow in CellsExergonic Reaction:Endergonic Reaction:

Chapter 6: Energy Flow in CellsCellular Respiration:(Exergonic)Photosynthesis:(Endergonic)

Chapter 6: Energy Flow in CellsActivation Energy: Energy required to “jumpstart” a chemicalreaction Must overcome repulsion of molecules due to negativecharged sRepelActivationEnergyNucleus

Chapter 6: Energy Flow in CellsExergonic Reactions:(“Downhill Reactions”)(Figure 6.2)

Chapter 6: Energy Flow in CellsEndergonic Reactions:(“Uphill Reactions”)(Figure 6.2)

Chapter 6: Energy Flow in CellsCoupled Reaction: An exergonic reaction supplies the energy needed to drivean endergonic reaction.

Chapter 6: Energy Flow in CellsCoupled Reaction: An exergonic reaction supplies the energy needed to drivean endergonic reaction.(Figure 6.3)

Chapter 6: Energy Flow in CellsHow is Cellular Energy Carried Between Reactions?Answer: Energy-Carrier MoleculesEnergy-Carrier Molecules: Rechargeable Battery: Pick-up Move Release Unstable Short-term storage Function within a single cellTypes:1) Adenosine triphosphate (ATP) Most common energy-carrier molecule Synthesized from adenosine diphosphate (ADP)

Chapter 6: Energy Flow in CellsATP:(Figure 6.4)

Chapter 6: Energy Flow in CellsCoupled ATP Reactions:

Chapter 6: Energy Flow in CellsHow is Cellular Energy Carried Between Reactions?Answer: Energy-Carrier MoleculesEnergy-Carrier Molecules: Rechargeable Battery: Pick-up Move Release Unstable Short-term storage Function within a single cellTypes:1) Adenosine triphosphate (ATP)2) Electron carriers (e.g. NADH)

Chapter 6: Energy Flow in CellsCoupled Electron-carrier Reactions:

Chapter 6: Energy Flow in CellsMetabolism: Sum of all chemical reactions Reactions are linked in metabolic pathwaysHow do Cells RegulateMetabolic Reactions? Photosynthesis (Chloroplast) Glycolysis (Mitochondria)1) Metabolic pathways2) Energy-carrier molecules3) Enzymes

Chapter 6: Energy Flow in CellsWhat are Enzymes?Answer: Molecules (proteins) that catalyze chemical reactionsWhat are Catalysts?Answer:Molecules that speed upchemical reactions Lower activation energy Catalysts only speed upreactions that would occurspontaneously Catalysts are not destroyedin the reaction

Chapter 6: Energy Flow in CellsEnzymes Biological CatalystsUnique Properties of Enzymes (compared to other catalysts):1) Enzymes are specific (High Specificity) Catalyze only one, or a few, chemical reactions Structure Dictates Specificity: Active Site: Location where substrates can bind Active sites have specific shape and charge

Chapter 6: Energy Flow in CellsEnzymes in Action:(Figure 6.9)

Chapter 6: Energy Flow in CellsEnzymes Biological CatalystsUnique Properties of Enzymes (compared to other catalysts):1) Enzymes are specific (High Specificity)2) Enzyme activity is regulated:A) Regulate synthesis of enzymeB) Regulate active state of enzyme Enzymes synthesized in inactive formand activated only when needed (e.g. pepsin)C) Feedback Inhibition: Enzyme activity is regulatedby product concentration

Chapter 6: Energy Flow in CellsFeedback Inhibition:(Figure 6.10)

Chapter 6: Energy Flow in CellsEnzymes Biological CatalystsUnique Properties of Enzymes (compared to other catalysts):1) Enzymes are specific (High Specificity)2) Enzyme activity is regulated:A) Regulate synthesis of enzymeB) Regulate active state of enzymeC) Feedback InhibitionD) Allosteric Regulation: Small molecules bind toenzyme, changing shape ofactive site

Chapter 6: Energy Flow in CellsAllosteric Regulation:(Figure 6.11)

Chapter 6: Energy Flow in CellsEnzymes Biological CatalystsUnique Properties of Enzymes (compared to other catalysts):1) Enzymes are specific (High Specificity)2) Enzyme activity is regulated:A) Regulate synthesis of enzymeB) Regulate active state of enzymeC) Feedback InhibitionD) Allosteric RegulationE) Competitive Inhibition: Molecules compete for theactive site of the enzyme

Chapter 6: Energy Flow in CellsCompetitive Inhibition:(Figure 6.11)

Chapter 6: Energy Flow in CellsThe activity of enzymes are influenced by their environment 3 - Dimensional structure of enzymes due to hydrogenbonding Factors affecting hydrogen bonding:1) pH (optimal 6 - 8)2) Salt Concentration3) Temperature Some enzymes require helper molecules to function Co-enzymes (bind with enzyme - assist in reaction) B - vitamins necessary for synthesis

Chapter 6: Energy Flow in Cells Enzymes Biological Catalysts Unique Properties of Enzymes (compared to other catalysts): 1) Enzymes are specific (High Specificity) 2) Enzyme activity is regulated: A) Regulate synthesis of enzyme B) Regulate active state of enzyme Enzymes synthesized