1. Chemical Reactions and Enzymes
Write words in green

2. What is a chemical reaction?
A chemical reaction is a process that changes one set of chemical substances (reactants) into another set of chemical substances (products).
Example: Photosynthesis
Reactants
Products

3. Cellular Chemical Reactions
Cellular chemical processes are referred to as metabolism.
Metabolism is a set of chemical reactions through which an organism builds up or breaks down materials as it carries out its life processes.

4. How do chemical reactions work?
Chemical reactions always involve the breaking of bonds in reactants and the synthesis (or making) of new bonds in products.

5. How do chemical reactions work?
Chemical reactions that release energy often occur spontaneously.
Every chemical reaction needs energy to get started, and that starting energy is called activation energy (EA).
activation energy clip

6. What is a catalyst?
A catalyst is a substance that speeds up the rate of a chemical reaction.
Catalysts work by lowering a reaction’s activation energy.

7. What are enzymes?
Enzymes are a type of protein that helps control and manage cell metabolism by making chemical reactions happen more efficiently.
Enzymes speed up chemical reactions by lowering activation energies.
Proteins make efficient catalysts because their shapes are very specific. enzyme clip

8. Parts of an Enzyme
Substrate – the molecules an enzyme metabolizes (the reactants)
Active Site – the site in which the substrate bonds.
The active site is a groove or depression on the surface of a enzyme.
Even the slightest change in the form of this site will alter the enzyme's function.
Induced fit is how the enzyme-substrate bonds.

9. Parts of an Enzyme Substrate Products Active Site Enzyme-Substrate
Complex
Enzyme

10. Effect of Enzymes Reaction pathway without enzyme Reactants
Activation energy
without enzyme
Activation
Energy with enzyme
Reactants
Reaction pathway
with enzyme
Products

11. What can affect Enzyme function?
Enzymes function best in specific conditions; environmental factors within the cell can affect how well the enzyme functions
Temperature – high temperatures can denature (break down) an enzyme, changing its shape. Enzymes work best at temperatures between 35oC and 40oC in humans.
pH range between 6 and 8 promotes optimum function. Higher or lower values negatively affect function.
Salts inhibit enzyme action.
These actions can denature a protein resulting in a substrate that no longer fits into the active site.
Normal human body temperature
ranges between 36.5 – 37.5oC
Human pH levels range from
1.5 – 8.0, depending on location

12. Question 1 Which structure is indicated by letter B? a.Active Site
b.Substrate
c.Enzyme-Substrate Complex
d.Competitive Inhibitor

13. Question 2
A student studying reactions with enzymes uses the graph to form a conclusion. What is the best conclusion a student can make based on the information on the graph?
a. The amount of activation energy is lower in reactions without enzymes.
b. The amount of activation energy needed is greater in reactions with enzymes.
c. A reaction with an enzyme lowers the activation energy needed.
d. As the reaction continues the amount of energy needed increases.

14. Question 3 Which statement does not describe the role of enzymes?
a. Enzymes synthesize molecules
b. Enzymes are specific to the molecules in a reaction.
c. Enzymes reactions are maximized within a spectific range of conditions.
d. Enzymes decrease the activation energy necessary for cell metabolism.

15. Question 4 Which structure is indicated by letter C? a.Active Site
b.Substrate
c.Enzyme
d.Competitive Inhibitor