The Search for Biofuels

Introduction:
A) Biofuels are quickly becoming an important alternative to fossil fuels. The basic requirement for a biofuels is that it comes from biomass. The first generation of biofuels were produced from food products such as corn and wheat. However, this was criticized because to took food away from the human population. Thus the second generation biofuels came from byproducts of food production. It converted much of the waste into fuels. The third generation of biofuels comes from algae. To break down biomass to produce ethanol, you must use enzymes. Enzymes speed up the rate of chemical reactions and are generally proteins. The reactant in an enzyme catalyzed reaction is caled the substrate. Enzymes speed up the rate of a reaction by reducing the activation energy needed for a reaction. Cellulose is found in the cell walls of plants, and is broken down by cellulases into glucose. By using cellulases, the biofuel industry can convert the cellulose into more easily usable forms, such as glucose. They then take the sugar and convert it into ethanol by microbial fermentation.

B) The purpose of this lab is to explore how cellulose from cell walls is broken down into glucose by enzymes. It has relevance to the research industry because they want to find an easy way to break down biomass into more usable forms of energy, such as glucose.

C) In this lab, we will be testing the effects of enzymes on a reaction. We will fill five test tubes with an artificial substrate (p-nitrolphenyl glucopyranoside)) and then add our enzymes (cellobiase). At specific timer periods we will add a base to stop the reaction and to act as an indicator to see how much product we got. In day 2 we will repeat this except we will use mushroom extract as our enzymes.

D) The control is this lab is a test tube with substrate but without an enzyme. The variables are how long the reaction occurs before we stop it with a base. I predict that the longer the reactions occur, the more product there will be.

Procedure: http://www.youtube.com/watch?v=v8TeTsnlKrg

Discussion: The data we received made sense. Looking at the five test tubes, they went from a light yellow (for the shortest time) to a more dark yellow (for the longest time). As the reaction went for a longer time, more product was produced. When we used mushroom extract, we had a similar effect. It was hard to distinguish if the mushroom extract was a faster enzyme that the cellobiase we used on the first day. Possible sources of error in this lab could be that if the reactant ran out during the time, then the reaction would stop. It did not seem to run out because the later test tubes each got darker. However, if we continued timing, at a certain point, the reactant would run out.