1. Chemical Reactions, Energy, and Enzymes

2. Chemical Reactions
A process that changes one set of chemicals into another set of chemicals
Two parts in a chemical reaction:

3. Chemical Reactions
A process that changes one set of chemicals into another set of chemicals
Two parts in a chemical reaction:
1) reactant—the element or compound that enters a chemical reaction

4. Chemical Reactions
A process that changes one set of chemicals into another set of chemicals
Two parts in a chemical reaction:
reactant—the element or compound that enters a chemical reaction
products—the elements or compounds produced by a chemical reaction

5. H2CO3 → CO2 + H20 Chemical Reactions
Chemical reaction always involved the breaking of bonds in reactants and formation of new bonds in products.
Examples: CO2 + H2O → H2CO3
H2CO3 → CO2 + H20

6. Energy
Energy in reactions—is either released or absorbed whenever chemical bonds form or are broken
Energy releasing reactions occur spontaneously.
Energy absorbing reactions cannot occur without a source of energy

7. Exergonic Reactions—release energy

8. Endergonic Reactions—absorb energy

9. Two types of Energy Potential Energy energy of position
“stored energy”
Kinetic Energy
energy of motion
used by organisms

10. Energy
During a chemical reaction, bonds break, energy is release, and potential energy is converted to kinetic energy to be used by cells to do work!!!

11. Activation Energy
Activation energy is the minimum amount of energy needed to start a chemical reaction

12. Enzymes biological protein catalysts
Catalyst—a substance that speeds up the rate of a chemical reaction by lowering a chemical reaction’s activation energy
Most enzymes end with ---ase
Ex. Maltase, sucrase, lactase
What carbohydrates do you think these enzymes help digest?

13. Enzymes Each chemical reaction in a living system requires an enzyme
Enzymes control the rate of a chemical reaction.

14. Enzyme Action—page 52

15. Enzyme Action
provides a site where reactants can be brought together in order to reduce energy for a reaction
Substrate—the reactant of enzyme catalyzed reactions
i.e. the substance the enzyme is working on

16. Enzyme-Substrate Complex
The enzyme + the substrate

17. Enzyme-Substrate Complex

18. Lock and Key Model
Think that an enzyme as a key that fits only one lock.
The “lock” is a specific molecule(substrate)
The “ key” is the enzyme.
The place where the enzyme joins the substrate is the active site.
When they join it is called the
Enzyme-substrate complex.

19. Lock and Key Model

20. Induced Fit Model A modified version of Lock and Key Model
Enzyme’s active site and the substrate do not need to fit exactly.
The shape of the enzyme slightly changes—making the enzyme and substrate fit more exactly.
The enzyme is a “flexible” key.

21. Induced Fit Model

22. Coenzymes Non-protein helper molecules
Help enzymes bind to the substrate
Many are made from vitamin molecules
They are reusable and needed in small amounts

23. Inhibitors Compounds that block active sites.
Can also distort the shape of substrate so enzymes won’t function properly

24. Denaturation Occurs when proteins are heated
Changes the shape of their molecules to distort and no longer function
Cannot work as an enzyme
Often occurs with foods that contain protein

25. Factors that affect enzyme activity
Temperature
pH value
Enzyme concentration
Substrate concentration

26. Important roles of Enzyme Activity
Regulating chemical pathways
Making materials that cells need
Transferring information