Reusable Liver (Ryan Hainey)

Author:

Ryan Hainey

Principle(s) Illustrated:

1. Enzyme Reactions

2. Energetics

3. Enzymes are not consumed in reactions

4. Homeostasis

Standards:

HS-LS1-3. Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.

Procedure:

1. Obtain 1 piece of beef or chicken liver, hydrogen peroxide, and 3 test tubes (ignition tubes work best)

2. Pour 10 ml of hydrogen peroxide into one test tube

3. Add a piece of liver and observe the reaction. Pay attention to the height of the bubbles.

4. Pour 10 ml of hydrogen peroxide into a second test tube.

5. Place the SAME piece of liver from 3. into the new test tube. Observe.

6. Repeat 4-5

Questioning Script

Prior knowledge & experience:

Students know from personal experience that the liver is an organ that detoxifies the blood and that hydrogen peroxide is used to clean and disinfect wounds. Students are unlikely to know (previous to instruction) that liver contains the enzyme catalase that can break apart hydrogen peroxide into oxygen gas and liquid water. Additionally students are unlikely to know the chemical equation for hydrogen peroxide: 2H₂0₂ or the reaction between Catalase and Hydrogen peroxide.

Root question:

Are enzymes reusable?

Target response:

The enzyme catalase in liver reacts with Hydrogen peroxide to produce water and oxygen gas. Enzymes are reusable because they are not consumed in reactions. Catalase will only cease to stop functioning if it is denatured or if its environmental conditions drastically change to diminish its biochemical activity.

For advanced students the root question can be changed to 'what are the optimal conditions of Catalase activity?'. Optimal conditions of Catalase can be tested by exposing the liver to differing pH, temperature, salinity, enzyme concentration or substrate concentration.

Common Misconceptions:

-Enzymes are not reusable

Discrepant Event: