1) Enzymes are proteins that catalyze (speed up) chemical reactions in the body. They do this by binding to substrate molecules and facilitating their transformation into product molecules. 2) The body is organized into a hierarchy of levels from smallest to largest: cells, tissues, organs, and organ systems. Cells work together to form tissues, tissues work together to form organs, and organs work together to form organ systems. 3) Enzyme activity can be destroyed by extreme heat, changes in pH, or inhibitor molecules that bind to the active site and prevent substrate binding. Without enzymes, important reactions like digestion could not occur fast enough.

1. Enzymes and Body Organization

2. Did you know…?
• Every box of Jello says “Do NOT add fresh or frozen
pineapple.” Why is that?

3. What is the function (job) of proteins?
• Proteins have many different jobs, such as:
1) Help cells move (example: help muscle fibers contract)
2) Help cells grow
3) Repair (heal) injuries to cells or to the body
4) Structure (example: building blocks for skin and bone)
5) Transport (carry) molecules (example: hemoglobin is a
protein in blood cells that carries oxygen)
6) Catalyze “speed up” reactions

4. What are enzymes?
• Proteins that catalyze (speed up) chemical reactions
in the body
• Enzymes are important because, without them,
important reactions, like digesting our food,
wouldn’t happen fast enough.
What is a substrate?
• The molecule that an enzyme binds to.

5. What is an active site?
• The part of the enzyme that binds to the substrate.
• The substrate HAS TO fit into the active site, like a
key fits in a lock, or else the enzyme won’t work.
• This is called the “lock and key” model.

6. Processing Piece:
• Look at the diagram. See if you can label the
enzyme, the active site, and the substrate.

7. How do enzyme-catalyzed reactions work?
1) Substrate binds to the enzyme’s active site.
2) The enzyme catalyzes (speeds up) a chemical reaction
that makes the substrate change shape; the substrate
changes into the products.
3) When the reaction is done, the enzyme releases the
products. The enzyme stays the same, ready to
catalyze another reaction.

8. Processing Piece:
• Illustrate the 3 steps of an enzyme catalyzed
reaction.
• Label the substrate, enzyme, and active site.

9. How does enzyme concentration affect
reaction rate?
• As enzyme concentration (the amount of enzyme)
increases, the reaction rate (how fast the reaction
happens) increases.

10. What is one example of an enzyme?
• Amylase is an enzyme in your saliva that breaks
down starch (a long polymer chain of
carbohydrates) into glucose (small monomers of
carbohydrates).

11. Processing Piece:
1) Why are enzymes important? (What do they do for
our bodies?)
2) What do you think would happen if we didn’t have
enzymes like amylase?

12. What 3 things can destroy enzymes?
1) Extreme heat (boiling temperatures)
2) pH change (like adding an acid or a base)
3) Molecules called “inhibitors” that bind to an
enzyme.
All three of these things change an enzyme’s shape,
so that it can no longer bind to the substrate.

13. How is the body organized?
• Cells  tissues  organs  organ systems
• Cells working together = a tissue
• Tissues working together = an organ
– Examples: Stomach, lungs, heart
• Organs working together = a system
– Examples: Respiratory system, circulatory system
• Systems working together = whole body

14. Processing Piece:
• Illustrate each level of organization in the body.

15. Processing Piece:
• Identify each of the following examples as cells,
tissues, organs, or organ systems.
1. A layer of muscle cells inside your stomach
2. Lungs (many tissues working together)
3. A cell in your stomach that secretes acid
4. Heart, veins, arteries, capillaries and blood cells all
working together to move blood around your body
5. A layer of fatty cells in your skin that work together to
keep you warm
6. Heart (many tissues working together to pump blood)

16. Exit Ticket
1. Draw a picture illustrating the 3 steps of an
enzyme- catalyzed reaction.
- In your drawing, label the enzyme, substrate, and
active site.
2. The enzymes in fresh pineapple dissolve Jello, but
the enzymes in canned pineapple don’t. Why is
this?
3. What are the 4 levels of organization in the body,
from smallest to largest?