1. Enzymes
Biology

2. Biochemical Reactions
Must occur at certain speeds, or rates, in order for them to be useful.
The rate at which a chemical reaction occurs depends on several factors: temperature, concentration, and surface area.
The addition of a catalyst can speed up a chemical reaction.

3. Enzyme
Is an organic catalyst that controls the rate of chemical reactions within cells.
Enzymes are proteins.
Without enzymes, many of the chemical reactions that occur in living things would not occur or would occur at rates too slow for the organism to survive.

4. Reactants and Products
Reactants are the substances that enter into a chemical reaction
Products are the substances that are formed during the reaction.
For chemical reactions to occur, reactants must come together with enough energy to break existing bonds and form new ones.

5. Enzymes
Enzymes provide reactants with a site where they can come together to react.
Reactants that are affected by enzymes are known as substrates.

6. Enzymes
The surface of an enzyme has a distinct shape that allows it to interact with only certain substrates.
A single organism may possess thousands of enzymes.
Each one is specific to a certain chemical reaction.

7. Active Site
The substrates bind to a part of the enzyme called the active site.
The shape of the substrate and the shape of the active site are opposite and fit together like a lock and key.

8. Enzyme-Substrate complex
The enzyme and substrate are held together by intermolecular forces, forming an enzyme-substrate complex.
This complex stays bound together until the reaction is complete.
When the reaction is done, the products are released.

9. Enzymes
Enzymes reduce the amount of energy that substrates need to react.
The activation energy of a reaction is the minimum amount of energy that colliding molecules must possess in order to react.
Enzymes reduce the activation energy.

10. Enzymes
Blood contains an enzyme called carbonic anhydrase that makes the reaction proceed about one million times faster than it would on its own.
If the reaction occurred on its own, carbon dioxide would build up in the bloodstream and become toxic.

11. Enzymes Enzymes can be affected by many factors.
One factor is temperature.
Enzymes work best in different organisms at different optimum temperatures
Humans: 37*C; Plants: 25*C
Enzymes are destroyed at above 50*C.

12. Enzymes pH is another factor that affects enzymes.
For most reactions, the optimum pH is 7.
Low or high pH values tend to inhibit (slow down) enzyme activity
Concentration is another factor affecting enzymes.
Substrate and enzyme molecules should be equal for optimum performance.