Goal 2:
Chemical Reactions
and Enzymes
I. Chemical Reactions
A. Occur in all cells of all living things = metabolism
1. Mass and energy are conserved
2. “food” is broken down for energy
B. Uses chemical formulas to represent compounds that are
changed into new compounds
1. arrow = makes/produces
2. plus sign = “and”
3. reactants – left of arrow
4. products – right of arrow
II. Energy in Reactions
A. Energy changes occur in all reactions
1. Released
a.
b.
Can occur spontaneously
Energy released as heat for growth,
breathing, brain activity, etc.
2. Absorbed
a.
b.
Require energy to occur
All living things require energy
i. plants use sun
ii. animals consume “food”
3. activation energy
is needed for both
types of reactions
a. Graphs
Energy-Released
Energy Absorbed
III. Enzymes: Organic Catalysts
A. some life reactions are too slow naturally
B. Some activation energies are too high to occur
1. lowers activation energy
a.
reactions happens faster
C. very specific: one enzyme per reaction
1.
only allows certain reactants to bind to certain enzymes
D. Enzyme Function
1. Enzyme-substrate complex
a.
Active site – place where reactant binds
i. Reduces energy needed for reaction
Draw:
E. Regulation of Enzyme Activity
1.
2.
3.
4.
Enzymes control chemical pathways
Make material cells need
Release energy
Temperature, pH and regulatory molecules affects the
activity of enzymes
a. Heat (increase in temperature) denatures (breaks down)
enzyme and does not allow it to function