6.1
What Physical Principles Underlie
Biological Energy Transformations?
119
There are two basic types of energy
and of metabolism 119
The first law of thermodynamics: Energy
is neither created nor destroyed 120
The second law of thermodynamics:
Disorder tends to increase 120
Chemical reactions release or consume
energy 122
Chemical equilibrium and free energy
are related 123
6.2
What Is the Role of ATP in Biochemical
Energetics? 123
ATP hydrolysis releases energy 124
ATP couples exergonic and endergonic
reactions 12
6.3
What Are Enzymes? 125
For a reaction to proceed, an energy
barrier must be overcome 126
Enzymes bind specific reactant molecules
126
Enzymes lower the energy barrier but
do not affect equilibrium 127
6.4 How
Do Enzymes Work? 128
Molecular structure determines enzyme
function 129
Some enzymes require other molecules
in order to function 129
Substrate concentration affects reaction
rate 130
6.5
How Are Enzyme Activities Regulated?
131
Enzymes can be regulated by inhibitors
131
Allosteric enzymes control their activity
by changing their shape 132
Allosteric effects regulate metabolism
133
Enzymes are affected by their environment
133
