After we discussed the results of our food lab, I did a demonstration about enzymes using liver and peroxide.
Liver tissue contains an enzyme called catalase that acts upon hydrogen peroxide to break it down into oxygen gas and liquid water. By breaking down the hydrogen peroxide, the liver prevents build up and damage to the organism's tissues.
An enzyme's ability to chemically match its substrate depends on maintaining its shape. Influences like high heat or altering the pH (too basic or too acidic) can serve to change the chemical shape of the enzyme and thus making it not fit its lock anymore.
The liver dropped into plain water had no reaction....why?? Because water doesn't chemically fit with the catalase and therefore it isn't chemically altered.
The liver dropped into peroxide gave off heat and bubbles; both are signs that a chemical reaction has occurred. Catalase has a specific chemical site that fits hydrogen peroxide thus causing it to decompose (break into smaller molecules). Even when the bubbles ceased, adding more hydrogen peroxide started the process all over again proving that the enzyme wasn't destroyed.
However, the liver boiled in the test tube failed to produce the same chemical reaction when exposed to the hydrogen peroxide. The high heat denatured or "messed with" the chemical structure of the enzyme. Just like melted or bending a key will affect its ability to work in a lock, heat can alter a chemical's ability to do a reaction.
Below is a video link that will review today's class demonstration.
Liver and Hydrogen Peroxide
Once at the website, type "enzyme" into the search box at the top right hand corner of the page. Choose the video that is described as "liver enzyme lab" that is 7 minutes and 33 seconds long. Click on the picture of the test tubes in their rack and enjoy!
1. Test on Organic Molecules Friday 9/3
2. Notebook Check Friday 9/3
3. Organic Molecule Review Project Due Wednesday 9/8
See you in the a.m.!