1. Biology
Chemical Reactions

2. Definitions for Section 8
Chemical reaction
Reactant
Product
Activation energy
Catalyst
Enzyme
Substrate
Active site pH
Acid
Base

3. Reactions
CHEMICAL REACTION: Process by which atoms or groups of atoms in subs are reorganized into different subs
Rust (Fe2O3) is formed when iron reacts and combines with oxygen
A chemical change has occurred

4. Chem reactions have several parts:
REACTANTS: The starting substances; left side of arrow
PRODUCTS: Subs formed during the reaction; right side of arrow
Arrow means “yields”
Reactants  Products
Example:
6CO2 + 6H2O + energy from sun  C6H12O6 + 6O2

5. Energy and Reactions What do you need to bake a cake?
After ingredients are mixed, energy must be applied
ACTIVATION ENERGY: The minimum amount of energy needed for reactants to form products
Ex. Flame applied to candle provides enough energy to begin reaction

6. This type of reaction called exergonic
Releases energy
Products have less energy than reactants
Examples: animals breaking down food, burning a candle

7. This is an example of an endergonic reaction
Requires high amount of energy to form products
Products have more energy than reactants
These reactions STORE ENERGY
Example: photosynthesis, making a candle

8. Kick It Up a Notch
Most chem reactions happen slowly (high act. energy)
CATALYST: Substance that lowers the activation energy needed to start a chemical reaction

9. In biological reactions, our catalyst is an ENZYME
ENZYME: Special protein that speeds up a chem reaction
“All enzymes are proteins but not all proteins are enzymes”
Can be identified with the ending “ase”
Examples: sucrase, DNA polymerase, lactase
Enzymes also break things down and synthesize things
Never “used up” in reactions
SUBSTRATE: The thing that binds to the enzyme

10. ACTIVE SITE: The specific area that a substrate connects to on the enzyme
Shape of active site very specific to substrate and enzyme
Called Lock-and-key mechanism
Enzymes work best when factors such as pH, temp, and salinity are in certain range
DENATURATION: Breakdown of a protein into an unusable state
Active sites

11. More Chemistry pH has an effect on enzyme activity
pH: measurement of the ACIDIC or BASIC a solution is
Scale of 0-14
ACIDS: Chemicals that produce hydrogen ions (H+); have pH from 0-7
Taste sour
Corrosive to metals
Turn litmus paper pink
Examples: citric, stomach, vinegar

12. BASES: Substances that have a pH from 7-14
Feel soapy or slimy
Strong bases can be corrosive to organic matter
Turn litmus paper blue
Examples: ammonia, sodium hydroxide (lye)

13. The pH scale measures from 0-14
Acids (0-7)
Bases (7-14)
Strongest acids have lowest pH, strongest bases highest
Water is neutral (pH of 7)

14. Section 5 Assignment Identify the reactants and products:
AB + CD  AD + BC
What is the purpose of a catalyst?
Why is no further energy required when a candle wick is ignited?
Draw a Venn diagram for exergonic and endergonic reactions.
When fevers hit 106 Farenheit, it’s time to call the doctor. Learning what you just did about proteins, why is that a bad thing?
Draw and label an enzyme that you create, the substrate that it will break down into products, and the active site. Do NOT use a picture from your book or notes. CREATE YOUR OWN!!

15. Section 5 Assignment Identify the reactants and products:
AB + CD  AD + BC
What is the purpose of a catalyst?
Why is no further energy required when a candle wick is ignited?
Draw a Venn diagram for exergonic and endergonic reactions.
When fevers hit 106 Farenheit, it’s time to call the doctor. Learning what you just did about proteins, why is that a bad thing?
Draw and label an enzyme that you create, the substrate that it will break down into products, and the active site. Do NOT use a picture from your book or notes. CREATE YOUR OWN!!

16. Lock-and-Key Mechanism of Enzymes
Active sites

17. The pH Scale