Biofuels

Introduction

Ethanol is a sustainable alternative to the oil that we use today. However, it can be difficult to break down the cellulose contained in plant cell walls, and for this reason an enzyme is needed.

Enzymes are used to speed up chemical reactions. They do this by positioning the reactant in a manner that reduces the activation energy, or the energy needed to make the reaction occur. Because they are not actually consumed in the reaction, they can be used multiple times. Reactions can also be sped up by increasing the temperature at which they occur.

Producing biofuels will become an increasingly important part of our lives in the future. Because there is no one perfect solution, multiple sources such as wind and solar power should accompany biofuels. It is crucial that we develop alternative fuel sources before our finite oil reserves are drained and we are left with no fuel whatsoever.

Procedure

Part 1
1. Measure 500 µl of stop solution into five cuvettes. The stop solution will be used to stop a sample of the reaction at a certain time, allowing us to see how much product has been created in that amount of time.

2. Pipet 2 ml of 1.5 mM substrate, or reactant, into a tube labeled "enzyme reaction". In this case the substrate is cellulose, found in plant cell walls.

3. Add 1 ml of cellobiase, an enzyme, to the tube. Cellobiase will speed up the reaction time, creating product faster.

4. At 1, 2, 4, 6, and 8 minutes, remove 500 µl from the reaction and add it to the appropriate cuvette. The stop solution in the cuvettes will halt the reaction, and dye the p-nitrophenol in the reaction yellow. The deeper the yellow, the more product has been formed.

Part 2
Repeat steps above, substituting ground mushroom for the cellulose in step 2. The mushroom is a potential natural fuel source.

Results

In each vial, the yellow was significantly more vivid. This proves that the reaction continued over the observed timeframe, creating more and more ethanol (the product). Because of the added cellubiase, the product was formed much faster than it would be if left to react without an enzyme.

The greatest chance for error is in grinding up the mushrooms with the mortar and pestle. It is possible to measure either too much or too little mushroom, and the mortar may be contaminated with chemicals from past work.