1. Energy, Chemical Reactions, and Enzymes

2. Energy the ability to move or change matter found in many forms
can be converted from one form into another

3. Chemical Reactions
process that changes one set of chemicals into another
always involves changes in the chemical bonds that join the atoms in the compounds

4. Chemical Reactions H2CO3 H2O CO2 reactants
substances that enter into a chemical reaction 
found on the left side of the arrow
products
substances produced by the chemical reaction
found on the right side of the arrow
H2CO3
H2O
CO2 +
carbon dioxide plus water forms carbonic acid

5. Energy in Reactions
some chemical reactions release energy and others absorb energy
energy changes are an important factor in determining whether a reaction will occur

6. Exothermic
chemical reaction that releases energy
C → A + B + Energy

7. Endothermic chemical reaction that needs to absorb energy to begin
A + B + Energy → C

8. Energy in Reactions Label each of the following reactions as either:
Energy-Releasing Reaction or
Energy-Absorbing Reaction
(from Holt Biology, pg. 39)

9. Use the location of the REACTANTS and PRODUCTS to help.

10. Energy in Reactions

11. Energy in Reactions

12. Activation Energy energy needed to start a chemical reaction
ex: spark plug in an engine

13. Hydrolysis of Sucrose by Sucrase
Enzymes
enzymes are biological catalysts
catalyst
substances that reduce the activation energy of a chemical reaction
reducing activation energy allows the reaction to occur more frequently and faster
Hydrolysis of Sucrose by Sucrase
McGraw - Hill

14. Enzymes & Activation Energy
Reaction pathway
without enzyme
Activation energy
Activation
energy
with enzyme
Reactants
Products

15. What type of macromolecule are most enzymes?
enzymes are proteins
these proteins enzymes increase the speed of chemical reactions
some enzymes break molecules apart

17. What type of macromolecule are most enzymes?
enzymes are proteins
these proteins enzymes increase the speed of chemical reactions
some enzymes break molecules apart
other enzymes put molecules together

19. What type of macromolecule are enzymes?
enzymes are proteins
these proteins enzymes increase the speed of chemical reactions
some enzymes break molecules apart
other enzymes put molecules together
do not get used up in a chemical reaction
help maintain homeostasis

20. Substrate substance on which an enzyme acts during a chemical reaction
substrate = reactants

22. Active Site How Enzymes Work McGraw - Hill
the location on an enzyme that attaches to a substrate
How Enzymes Work
McGraw - Hill

24. Enzyme Specificity
enzymes are specific because only its substrate fits into its active site
enzymes are similar to a lock and key

25. Enzyme Efficiency work well only within a certain set of conditions
changes in conditions like pH and temperature can change the shape of the protein
when the substrate no longer fits the active site, the enzyme will not work
the “lock and key” no longer fit in one another

26. lactose  glucose + galactose
Example
lactase is an enzyme that breaks down milk sugar (lactose)
lactase
lactose  glucose + galactose

27. lactose  glucose + galactose
Why is lactase written above the arrow and not included in the chemical equation?
because enzymes (like lactase) are not used up in chemical reactions
they can be re-used over and over again for the same type of reaction
lactase
lactose  glucose + galactose