1. 2-4 Chemical Reactions and Enzymes
Chemical Reaction – a process that changes one set of chemicals into another.
Products – elements & compounds that are produced by a reaction
Reactants – elements & compounds that enter into a reaction.
Products
Reactants

2. Energy in Reactions
Exergonic Reactions - some chemical reactions release energy
Happen spontaneously
Ex: HCl + Zn H + ZnCl
Endergonic Reactions - some chemical reactions absorb energy
Will not occur without a source of energy
H2 + O H2O
Activation Energy: the energy needed to start a chemical reaction.

3. Exergonic vs. Endergonic
“Uphill” reaction
Requires Energy (Activation Energy)
Absorbs Energy
“Downhill” reaction
Spontaneous
Releases Energy

4. Enzymes
Catalyst – a substance that speeds up a chemical reaction by lowering the activation energy.
Enzymes – are proteins that act as a biological catalyst.

5. Enzyme Action
Substrate
Active Site
Enzyme
Substrate – the reactants of an enzyme catalyzed reaction
Active Site – where the substrate and enzyme join.
Have complimentary shapes
Can only bind with a specific molecule – “induced fit”
Animation

6. Regulation of Enzyme Activity
Enzymes work best at certain pH levels and temperatures.
Most enzymes in humans work best at 37 C
Denaturation – a change in the enzymes shape.
Enzyme becomes nonfunctional
Heat and pH can cause denaturation
Some enzymes can be turned on and off
Lactose intolerance
Animation

8. Graphic Organizer Assignment
Use the large sheet of paper provided to create graphic organizers as follows:
T-Chart – Use Functional groups and list structure vs. what the group makes (e.g. alcohol, acid, ketone etc.)
Spider Map – Use “enzyme” for the center circle and elaborate on information related to enzymes from there.
Venn Diagram – Compare and contrast endergonic and exergonic reactions, include a graph of each type
Vocabulary Word Map – Use “organic molecules” to start, then list carbohydrates, lipids, proteins and nucleic acids. Add vocab related to these four classes of organic molecules. Draw at least one structure for each of the four classes.

9. What letter represents the product?
X axis
Y axis B A D C
What letter represents the product?
What letter represents the reactant?
What letter represents the activation energy?
How should the x and y axis be labeled?
Is the reaction exergonic or endergonic? Explain

10. Vocab for 2nd constructed response:
Enzyme – a protein that is a catalyst (speeds up a chemical reaction)
Reactants – compounds that enter a reaction
Products – compound produced by a reaction
Substrate – reactant(s) that join with enzyme
Active site – where enzyme and substrate join
Denatured – a change in the enzyme’s shape
Structure (shape) and function - enzymes must have the right shape to work properly
Othe Factors that affect enzyme function:
Temperature pH
Concentration of enzyme