2-4 Chemical Reactions and Enzymes
Metabolism: All living need to carry out chemical
reactions in order to stay alive.
Energy is released or absorbed whenever chemical
bonds are formed or broken in a chemical reaction.
• Exergonic Reaction: any chemical reaction that
releases energy.
– Sometimes occur spontaneously
– Sometimes energy is needed to start an exergonic
reaction.
– Activation Energy: the energy needed to get a
chemical reaction started.
2-4 Chemical Reactions and Enzymes
Examples of exergonic reactions
2-4 Chemical Reactions and Enzymes
2-4 Chemical Reactions and Enzymes
• Many of the chemical reactions • Enzymes: proteins
that speed up the
in cells have activation energy
chemical reactions of
that is too high and occur to
cells.
slow in order for the cell to
(Enzymes are
survive.
biological catalysts)
• To overcome this problem cells
make catalysts: a substance
that speeds up the rate of a
chemical reaction by lowering
the activation energy.
2-4 Chemical Reactions and Enzymes
• Explain how the
enzyme affects
the chemical
reaction.
• Does the enzyme
have any affect
on the product of
the reactants?