Chapter 6: Energy, Enzymes, and Metabolism CHAPTER 6 Energy, Enzymes, and Metabolism Life: the...
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Chapter 6: Energy, Enzymes, and Metabolism CHAPTER 6 Energy, Enzymes, and Metabolism Life: the Science of Biology, Purves 6 th ed.
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Transcript of Chapter 6: Energy, Enzymes, and Metabolism CHAPTER 6 Energy, Enzymes, and Metabolism Life: the...
Chapter 6: Energy, Enzymes, and Metabolism
CHAPTER 6Energy, Enzymes, and
Metabolism
Life: the Science of Biology, Purves 6th ed.
Chapter 6: Energy, Enzymes, and Metabolism
Chapter 6: Energy, Enzymes, and MetabolismEnergy and Energy ConversionsEnergy and Energy Conversions
ATP: Transferring Energy in Cells ATP: Transferring Energy in Cells
Enzymes: Biological Catalysts Enzymes: Biological Catalysts
Chapter 6: Energy, Enzymes, and Metabolism
Chapter 6: Energy, Enzymes, and MetabolismMolecular Structure Determines Enzyme Molecular Structure Determines Enzyme
Function Function
Metabolism and the Regulation of Metabolism and the Regulation of EnzymesEnzymes
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• Energy is the capacity to do work. Energy is the capacity to do work.
Potential energy is the energy of state Potential energy is the energy of state or position; it includes energy stored in or position; it includes energy stored in chemical bonds. Kinetic energy is the chemical bonds. Kinetic energy is the energy of motion.energy of motion.
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• Potential energy can be converted to
kinetic energy, which does work. Review Figure 6.1
Chapter 6: Energy, Enzymes, and Metabolism
6.1
Figure 6.1Figure 6.1
figure 06-01.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• The first law of thermodynamics tells
us energy cannot be created or destroyed. The second tells us that, in a closed system, the quantity of energy available to do work decreases and unusable energy increases. Review Figure 6.3
Chapter 6: Energy, Enzymes, and Metabolism
6.3
Figure 6.3Figure 6.3
figure 06-03.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• Living things obey the laws of
thermodynamics. Organisms are open systems that are part of a larger closed system. Review Figure 6.4
Chapter 6: Energy, Enzymes, and Metabolism
6.4
Figure 6.4Figure 6.4
figure 06-04.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• Changes in free energy, total energy, Changes in free energy, total energy,
temperature, and entropy are related temperature, and entropy are related by the equation:by the equation:• Total E = Usable E + Unusable ETotal E = Usable E + Unusable E• Free E = enthalpy – (Abs. Temp. x Free E = enthalpy – (Abs. Temp. x
Entropy)Entropy)G =G = H – TH – TSS
• Enthalpy = total energyEnthalpy = total energy• Entropy = unusable energyEntropy = unusable energy• Free Energy = usable energyFree Energy = usable energy
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• Spontaneous, exergonic reactions
release free energy and have a negative G.
• Non-spontaneous, endergonic reactions take up free energy, have a positive G, and proceed only if free energy is provided.
• Review Figure 6.5
Chapter 6: Energy, Enzymes, and Metabolism
6.5
Figure 6.5Figure 6.5
figure 06-05.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Energy and Energy Conversions• The change in free energy of a
reaction determines its point of chemical equilibrium, at which forward and reverse reactions proceed at the same rate.
• For spontaneous, exergonic reactions, the equilibrium point lies toward completion.
• Review Figure 6.6
Chapter 6: Energy, Enzymes, and Metabolism
6.6
Figure 6.6Figure 6.6
figure 06-06.jpg
Chapter 6: Energy, Enzymes, and Metabolism
ATP: Transferring Energy in Cells• ATP serves as an energy currency in ATP serves as an energy currency in
cells. Hydrolysis (addition of Hcells. Hydrolysis (addition of H++ and and OHOH++ from water) of ATP releases a from water) of ATP releases a relatively large amount of free energy. relatively large amount of free energy.
• Review Figure Review Figure 6.86.8
Chapter 6: Energy, Enzymes, and Metabolism
6.8
Figure 6.8Figure 6.8
figure 06-08.jpg
Chapter 6: Energy, Enzymes, and Metabolism
ATP: Transferring Energy in Cells• The ATP cycle couples exergonic and
endergonic reactions, transferring free energy from the exergonic to the endergonic reaction.
• Review Figures 6.9, 6.10
Chapter 6: Energy, Enzymes, and Metabolism
6.9
Figure 6.9Figure 6.9
figure 06-09.jpg
Chapter 6: Energy, Enzymes, and Metabolism
6.10
Figure 6.10Figure 6.10
figure 06-10.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Enzymes: Biological Catalysts• The rate of a chemical reaction is The rate of a chemical reaction is
independent ofindependent of G (free energy)G (free energy) but is but is determined by the size of the determined by the size of the activation energy barrier. activation energy barrier.
• Catalysts speed reactions by lowering Catalysts speed reactions by lowering the barrier. the barrier.
• Review Figures Review Figures 6.116.11, , 6.126.12
Chapter 6: Energy, Enzymes, and Metabolism
6.11
Figure 6.11Figure 6.11
figure 06-11.jpg
Chapter 6: Energy, Enzymes, and Metabolism
6.12
Figure 6.12Figure 6.12
figure 06-12.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Enzymes: Biological Catalysts• Enzymes are biological catalysts,
highly specific for their substrates. • Substrates bind to the active site,
where catalysis takes place, forming an enzyme–substrate complex.
• Review Figure 6.13
Chapter 6: Energy, Enzymes, and Metabolism
6.13
Figure 6.13Figure 6.13
figure 06-13.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Enzymes: Biological Catalysts• At the active site, a substrate can be At the active site, a substrate can be
oriented correctly, chemically oriented correctly, chemically modified, or strained. modified, or strained.
• As a result, the substrate readily forms As a result, the substrate readily forms its transition state, and the reaction its transition state, and the reaction proceeds. proceeds.
• Review Figures 6.14, 6.15Review Figures 6.14, 6.15
Chapter 6: Energy, Enzymes, and Metabolism
6.14
Figure 6.14Figure 6.14
figure 06-14.jpg
Chapter 6: Energy, Enzymes, and Metabolism
6.15
Figure 6.15Figure 6.15
figure 06-15.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Enzymes: Biological Catalysts• Substrate concentration affects the
rate of an enzyme-catalyzed reaction. Review Figure 6.16
Chapter 6: Energy, Enzymes, and Metabolism
6.16
Figure 6.16Figure 6.16
figure 06-16.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Molecular Structure Determines Enzyme Function• The active site where substrate binds The active site where substrate binds
determines the specificity of an determines the specificity of an enzyme. Upon binding to substrate, enzyme. Upon binding to substrate, some enzymes change shape, some enzymes change shape, facilitating catalysis. Review Figures facilitating catalysis. Review Figures 6.13, 6.186.13, 6.18
Chapter 6: Energy, Enzymes, and Metabolism
6.18
Figure 6.18Figure 6.18
figure 06-18.jpg
Chapter 6: Energy, Enzymes, and Metabolism
Metabolism and the Regulation of Enzymes• Metabolism is organized into Metabolism is organized into
pathways: the product of one reaction pathways: the product of one reaction is a reactant for the next. Each is a reactant for the next. Each reaction is catalyzed by an enzyme.reaction is catalyzed by an enzyme.
Chapter 6: Energy, Enzymes, and Metabolism
Metabolism and the Regulation of Enzymes• Enzymes are sensitive to their
environment. Both pH and temperature affect enzyme activity. Review Figures 6.25, 6.26
Chapter 6: Energy, Enzymes, and Metabolism
6.25
Figure 6.25Figure 6.25
figure 06-25.jpg
Chapter 6: Energy, Enzymes, and Metabolism
6.26
Figure 6.26Figure 6.26
figure 06-26.jpg
