chapter PRINCIPLES OF BIOENERGETICS 13.1 Bioenergetics and Thermodynamics 490 heat and that this process of 13.2 Phosphoryl Group Transfers and AIP 496 respiration is essential to life He observed that 13.3 Biological Oxidation-Reduction Reactions 507 in general, respiration The total energy of the universe is constant; the total bustion of carbon and hy entropy is continually increasing drogen, which is entirely -Rudolf Clausius, The Mechanical Theory of Heat with Its similar to that which oc- m-Engine and to the Physic urs in a lighted lamp or Properties of Bodies, 1865(trans. 1867) candle, and that, from this int of view. animals that respire are true com- 1743-1794 The isomorphism of entropy and information establishes a bustible bodies that burn link between the two forms of power: the power to do and and consume themselves.. One may say that this the power to direct what is done analogy between combustion and respiration has francois Jacob, La logique du vivant: une histoire de Iheredite not escaped the notice of the poets, or rather (The Logic of Life: A History of Heredity), 1970 philosophers of antiquity, and which they had heaven, this torch of Prometheus, does not only rep sent an ingenious and poetic idea, it is a faithful picture of the operations of nature, at least for an ness energy and to channel it into biological work is a imals that breathe: one may therefore say, with the fundamental property of all living organisms; it must ancients, that the torch of life lights itself at the mo- have been acquired very early in cellular evolution. Mod ment the infant breathes for the first time. and it ern organisms carry out a remarkable variety of energy does not extinguish itself except at death. transductions, conversions of one form of energy to an- In this century, biochemical studies have revealed other. They use the chemical energy in fuels to bring much of the chemistry underlying that"torch of life about the synthesis of complex, highly ordered macro- Biological energy transductions obey the same physical molecules from simple precursors. They also convert the laws that govern all other natural processes. It is there. chemical energy of fuels into concentration gradients fore essential for a student of biochemistry to under- and electrical gradients, into motion and heat, and, in a stand these laws and how they apply to the flow of few organisms such as fireflies and some deep-sea fish, energy in the biosphere. In this chapter we first review to light. Photosynthetic organisms transduce light en. the laws of thermodynamics and the quantitative rela- ergy into all these other forms of energy The chemical mechanisms that underlie biologica tionships among free energy, enthalpy, and entropy. We hen describe the special role of ATP in biologi energy transductions have fascinated and challenged Mlogists for centuries. Antoine Lavoisier, before he lost his head in the French Revolution, recognized that an- avoisier,a( 1862)Oeuvres de lavoisier, imals somehow transform chemical fuels(foods) into Imperiale,Paris.chapter Living cells and organisms must perform work to stay alive, to grow, and to reproduce. The ability to har￾ness energy and to channel it into biological work is a fundamental property of all living organisms; it must have been acquired very early in cellular evolution. Mod￾ern organisms carry out a remarkable variety of energy transductions, conversions of one form of energy to an￾other. They use the chemical energy in fuels to bring about the synthesis of complex, highly ordered macro￾molecules from simple precursors. They also convert the chemical energy of fuels into concentration gradients and electrical gradients, into motion and heat, and, in a few organisms such as fireflies and some deep-sea fish, into light. Photosynthetic organisms transduce light en￾ergy into all these other forms of energy. The chemical mechanisms that underlie biological energy transductions have fascinated and challenged biologists for centuries. Antoine Lavoisier, before he lost his head in the French Revolution, recognized that an￾imals somehow transform chemical fuels (foods) into heat and that this process of respiration is essential to life. He observed that ... in general, respiration is nothing but a slow com￾bustion of carbon and hy￾drogen, which is entirely similar to that which oc￾curs in a lighted lamp or candle, and that, from this point of view, animals that respire are true com￾bustible bodies that burn and consume themselves . . . One may say that this analogy between combustion and respiration has not escaped the notice of the poets, or rather the philosophers of antiquity, and which they had ex￾pounded and interpreted. This fire stolen from heaven, this torch of Prometheus, does not only rep￾resent an ingenious and poetic idea, it is a faithful picture of the operations of nature, at least for an￾imals that breathe; one may therefore say, with the ancients, that the torch of life lights itself at the mo￾ment the infant breathes for the first time, and it does not extinguish itself except at death.* In this century, biochemical studies have revealed much of the chemistry underlying that “torch of life.” Biological energy transductions obey the same physical laws that govern all other natural processes. It is there￾fore essential for a student of biochemistry to under￾stand these laws and how they apply to the flow of energy in the biosphere. In this chapter we first review the laws of thermodynamics and the quantitative rela￾tionships among free energy, enthalpy, and entropy. We then describe the special role of ATP in biological PRINCIPLES OF BIOENERGETICS 13.1 Bioenergetics and Thermodynamics 490 13.2 Phosphoryl Group Transfers and ATP 496 13.3 Biological Oxidation-Reduction Reactions 507 The total energy of the universe is constant; the total entropy is continually increasing. —Rudolf Clausius, The Mechanical Theory of Heat with Its Applications to the Steam-Engine and to the Physical Properties of Bodies, 1865 (trans. 1867) The isomorphism of entropy and information establishes a link between the two forms of power: the power to do and the power to direct what is done. —François Jacob, La logique du vivant: une histoire de l’hérédité (The Logic of Life: A History of Heredity), 1970 13 489 *From a memoir by Armand Seguin and Antoine Lavoisier, dated 1789, quoted in Lavoisier, A. (1862) Oeuvres de Lavoisier, Imprimerie Impériale, Paris. Antoine Lavoisier, 1743–1794