1. Chemical Reactions & Enzymes

2. Chemical Reactions
Reactants
Products
Change substances into different ones by breaking and forming chemical bonds
Reactants are the substances changed during a chemical reaction.
Products are the substances made by a chemical reaction
Activation Energy: amount of energy needed to start a reaction

3. Exothermic Reactions Exo = exit; thermic = heat
Defined: Release more energy than it absorbs
Light & heat
Ex: Cellular Respiration
Process that creates energy for cells
Chemical energy released for cells…
Heat energy released for warmth

4. Endothermic Reactions
Endo = within; thermic =heat
Defined: Absorb more energy than it releases
Ex: Photosynthesis
The sugar produced has more energy (stored in the bonds) than the water and CO2

5. Enzymes
Enzymes reduce energy needed (activation energy) to start a chemical reaction
Speeds up a reaction
Aka: Catalyst
reusable

6. Controlled Settings Human body ~98.6°F
Can’t raise body temp to start reactions.
Internal reactions would be too slow to sustain life without a catalyst
Ex: Saliva
Breaks down starch 1,000,000x faster with amylase

7. Enzyme Structure
Enzyme shape allows specific reactants to bind together
Reactants = substrate
Ex: Amylase & Amylose: Amylose (starch) is the substrate because it binds to amylase
Substrates binds to activation sites on the enzyme (key fitting into a lock)
Once bound to enzyme, substrates bonds weakened
Substrates bonds break
New products formed (new bonds form)

9. Review
1) How do enzymes speed up chemical reactions? 2) What are the molecules called that react with enzymes? 3) Given the following chemical formula list the products and reactants: 6O2 + C6H12O6  6CO2 + 6H2O 4) What are the substances that are changed during a chemical reaction called? 5) What is another term for a catalyst? 6) Why can’t the human body raise its temperature to allow chemical reactions to happen quicker? 7) Given Amylase and Amylose, which is the substrate? 8) What do enzymes weaken between molecules?