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9 Bioenergetics
The calcium ion permeability for a typical cell is about 0.001 that of the
potassium ion. The concentration of calcium inside a cell is about a million times
less than potassium, while on the outside, their concentrations are comparable.
Voltage-dependent calcium channel gates play an important role in muscle cells
and in heart pacemaker cells.
9.21 Biochemical Reactions
Live systems take in energy and material, convert less ordered material into more
ordered substances, and expel heat and waste material. This process on Earth occurs
in life systems through organic chemistry, i.e. the chemistry of carbon compounds.
All biochemical processes are consistent with the laws of thermodynamics and the
known interactions of molecules.
A biochemical reaction is a process which chemically transforms organic molecular type. All chemical reactions are driven by a combination of natural molecular
forces and the tendency toward greater disorder inherent in the statistical behavior
of macroscopic systems. Moreover, during reactions of any kind, the symmetries of
nature require that certain quantities determined before a reaction will be preserved
during a reaction. The symmetries of space-time cause total energy, momentum, and
angular momentum to be conserved. Internal symmetries in the interactions between
particles require that certain additive charges are conserved during reactions, such
as the electric charge, the leptonic charge, and the baryonic charge. Electrons carry
leptonic charge, and atomic nuclei carry baryonic charge equal to the number of
protons and neutrons present.
Reactions can transform the molecular components within a system, changing
the number of particles in individual components or their arrangement. Chemical
reactions involve only the outer electrons of atoms and molecules (the ‘valence’
electrons). Thus, a chemical reaction may rearrange the state and binding of atoms,
but it preserves the total number of each kind of atom. Since the outer electrons are
held to atoms with binding energies from zero to less than about 20 electron-volts
(about 24 kcal/mole), energy transfers during a chemical reaction are also typically
in this range.
The energy released in a chemical reaction is far less than the Einsteinian energy
stored in the mass of the reactants, so the mass before a chemical reaction is
very close to the mass after, usually to within less than ten parts in a billion. The
energy transferred from a system during a chemical reaction necessarily changes
the mass of that system, but chemical scales are not sufficiently sensitive to detect
that change. The condition of approximate mass preservation will be insured by
the stoichiometric balancing of numbers of each type of atom before and after a
reaction.
As chemical reactions in the laboratory and in life systems on Earth take place
predominantly at nearly constant temperature and pressure, the Gibbs form of the
second law of thermodynamics is convenient to characterize such reactions and
9 Bioenergetics
The calcium ion permeability for a typical cell is about 0.001 that of the
potassium ion. The concentration of calcium inside a cell is about a million times
less than potassium, while on the outside, their concentrations are comparable.
Voltage-dependent calcium channel gates play an important role in muscle cells
and in heart pacemaker cells.
9.21 Biochemical Reactions
Live systems take in energy and material, convert less ordered material into more
ordered substances, and expel heat and waste material. This process on Earth occurs
in life systems through organic chemistry, i.e. the chemistry of carbon compounds.
All biochemical processes are consistent with the laws of thermodynamics and the
known interactions of molecules.
A biochemical reaction is a process which chemically transforms organic molecular type. All chemical reactions are driven by a combination of natural molecular
forces and the tendency toward greater disorder inherent in the statistical behavior
of macroscopic systems. Moreover, during reactions of any kind, the symmetries of
nature require that certain quantities determined before a reaction will be preserved
during a reaction. The symmetries of space-time cause total energy, momentum, and
angular momentum to be conserved. Internal symmetries in the interactions between
particles require that certain additive charges are conserved during reactions, such
as the electric charge, the leptonic charge, and the baryonic charge. Electrons carry
leptonic charge, and atomic nuclei carry baryonic charge equal to the number of
protons and neutrons present.
Reactions can transform the molecular components within a system, changing
the number of particles in individual components or their arrangement. Chemical
reactions involve only the outer electrons of atoms and molecules (the ‘valence’
electrons). Thus, a chemical reaction may rearrange the state and binding of atoms,
but it preserves the total number of each kind of atom. Since the outer electrons are
held to atoms with binding energies from zero to less than about 20 electron-volts
(about 24 kcal/mole), energy transfers during a chemical reaction are also typically
in this range.
The energy released in a chemical reaction is far less than the Einsteinian energy
stored in the mass of the reactants, so the mass before a chemical reaction is
very close to the mass after, usually to within less than ten parts in a billion. The
energy transferred from a system during a chemical reaction necessarily changes
the mass of that system, but chemical scales are not sufficiently sensitive to detect
that change. The condition of approximate mass preservation will be insured by
the stoichiometric balancing of numbers of each type of atom before and after a
reaction.
As chemical reactions in the laboratory and in life systems on Earth take place
predominantly at nearly constant temperature and pressure, the Gibbs form of the
second law of thermodynamics is convenient to characterize such reactions and