1. Ch.2-4 Chemical Reactions & Enzymes
Chemistry of life

2. POINT > Define chemical reaction
POINT > Distinguish exothermic and endothermic reactions
POINT > Define activation energy
POINT > Describe the role of enzymes and enzyme regulation

3. POINT > Define chemical reaction
A chemical reaction is a process that changes one set of chemicals into another Reactants: substances that enter into a reaction Products: substances produced by a reaction C6H12O6 + 6O2  6CO2 + 6H2O

4. WB CHECK:
C6H12O6 + 6O2  6CO2 + 6H2O What is one product in the chemical reaction shown above?

5. POINT > Distinguish exothermic and endothermic
Exothermic reactions release energy
The products have less energy than the reactants
This usually involves breaking down molecules
C6H12O6 + 6O2  6CO H2O

6. POINT > Distinguish exothermic and endothermic
Endothermic reactions absorb energy. The products have more energy than the reactants Usually involves building molecules 6CO2 + 6H2O  C6H12O6 + 6O2

7. WB CHECK:
When you exercise, your muscle cells break glycogen down into glucose, then break down glucose to get energy (aerobic respiration). Are those reactions exothermic or endothermic?
After intense exercise your muscle cells may need repairs. Do you think the “repair” reactions are exothermic or endothermic?

8. POINT > Define activation energy
Most reactions need a little “push” to get started The activation energy is the amount of energy needed to get a reaction started

9. POINT > Describe the role of enzymes and enzyme regulation
Enzymes are proteins that speed up the rate of a reaction. They are biological catalysts A catalyst is something that speeds up a reaction Enzymes work by lowering the activation energy The substrate is the reactant that the catalyst binds to

10. WB CHECK >
How do enzymes increase reaction rates in cells?
What is the molecule an enzyme binds to called?
What is a catalyst?

11. POINT > Describe the role of enzymes
Enzymes make life possible! The thousands of reactions happening in cells every second would be too slow without them Enzymes can increase reaction rates by x 10,000,000! Many diseases, such as Alzheimers, Parkinsons, and many others are caused by faulty enzymes

12. POINT > Describe the role of enzymes and enzyme regulation
Substrates bind to the active site of the enzyme
Enzymes and substrates fit together precisely, like lock & key

13. POINT > Describe the role of enzymes and enzyme regulation
Many factors influence enzyme activity:
Temperature pH
Concentration of substrate
Other molecules

14. WB CHECK:
What are 3 factors that affect enzyme activity?
What type of bond holds two water molecules to each other?
What type of bond holds the atoms in one water molecule to each other?
Which type of macromolecule are cell membranes mostly composed of?

15. Homework Read pp 50-53 # 1-3 page 53 Pre-read 3.1 Ecology
Quiz coming on Chapters 1-2