Monday, November 4, 2013

Enzyme Catalyst Lab

Purpose:

2B) The purpose of this part of the lab was to determine the amount of hydrogen peroxide (H2O2) initially present in a 1.5% solution. We were testing the concept of establishing a baseline without adding catalase (enzyme) to the reaction mixture. The dependent variable is the hydrogen peroxide (H2O2), water, and H2SO4. The independent variable is the amount of KMnO4 used in the burette to get the solution a persistent pink or brown color. 


2C) The purpose of this part of the lab was to determine the course of an enzymatic reaction in a reaction. In order to do this, we needed to measure the amount of substrate disappearing over time increments of 10, 30, 60, 90, 120, 180, and 360 seconds. We were testing the concept of the amount of substrate decomposed in these time amounts. The dependent variable was the amount of hydrogen peroxide, yeast, and water that were combined in the beaker while the independent variable was the amount of time the reaction was allowed to take place before the KMnO4 was added to stop the reaction. 

Introduction: 
        This lab deals with enzymes, catalyze, and the reaction of the two together. Enzymes are proteins produced by living cells, and a catalyst is a substance that speeds up the reaction and lowers reaction energy.  Enzyme catalyst connects to a site of an enzyme, lowering the amount of energy required to produce a reaction with the substrate.
In this experiment we used the titration method to determine the quantity of substances in many different types of solutions.This experiment will help us to observe how catalyst enzymes work to speed up the reactions and turn hydrogen peroxide into water and oxygen gas.  By letting these reactions take place for different amounts of time, we could compare and contrast which conditions and time limits cause more of a reaction and which cause less. WE LOVE ENZYMES!!!!  :)

Methods: 

2B) We tested a baseline as a comparison for the experiment. We mixed water, hydrogen peroxide, and sulfuric acid. After removing a 5 mL sample of the mixture and added KMNO4 until the pink color remained visible in the liquid.

2C) We had 7 different cups labeled with 7 different times (10, 30, 60, 90, 120, 180, 360 seconds).  In each cup we put the same amount of hydrogen peroxide, yeast, and acid; however, after adding the hydrogen peroxide and yeast, we controlled the amount of time we let the reaction take place. In order to stop the reaction we added sulfuric acid after a specific number of seconds. The times listed on the cups represented the amount of time we let the yeast and hydrogen peroxide react. Then, we removed a 5 mL sample and added KMNO4 until the pink color remained visible in the liquid. The longer we let the reaction take place, the less KMNO4 was needed in order to make the color stay.
Data from part 2C

Data used from part 2C
Graph 2.1
Discussion: 

2B) In this experiment the level of KMnO4 the burette dropped from 27 ml to 24 ml. This means that the level of KMnO4 dropped 3.1 ml.  These results are important because the baseline is used in every experiment. The baseline is used too test the amount of H2O2 in a 1.5 solutions.


2C) In this experiment we want to test the rate of spontaneous conversion of H2O2 without an enzyme. We had to use the baseline again but this time the baseline difference between the initial and final reading is 3.7 instead of 3.1. It is different because we had to make a new baseline. The baseline is not supposed to sit for 24 hours. We have to account for the natural breakdown of H2O2. It can naturally breakdown but also external factors can make it breakdown more like enzyme and temperature change in the room. Without a enzyme only .6  ml has been decomposed. Using the formula (ml baseline - ml 24 hour / ml  baseline) X 100 we found out that 19.3 % has been decomposed. It makes sense that the number is low because there was no enzymes in the  experiment. The enzymes can help lower the activation energy.  Activation energy is how much energy it takes to start a reaction. H2O2 could have a high activation energy and that could be a reason why not a lot of H2O2 decomposed. I think the way that the experiment was set up it was good. It was beneficial that we all used the same 24 hour solution. It helps us standardize our results. If even all made our own 24 hour solution all of our results could be greatly varied, like we could mess up on the make up of the solution or how much time it spends sitting.


2D) In this experiment we tested the same reaction as the last experiment but instead of no enzyme we added enzymes to the experiment. In this experiment we see that as time progressive  the enzymatic rate lowered. The highest rate is the first in the first time interval (0-10) . It was the highest because iit had the highest catalysis amount and the most amount of H2O2 to decompose. The lowest rate was the last time interval  (180 -360) there are 2 possible reason why it is the lowest. One is the H+ content makes the solution more basic. This moves the solution away from its optimal ph, thus causing the enzyme to denature. Denaturing is when the enzyme becomes biologically inactive because the proteins begins to unfold. Another reason could be is that all the catalysis amount is at the lowest because all the enzymes are already being used.  This causes an inhibiting effect on reaction. Inhibiting is when the reaction is stopped or slowed down. If we were to lower the temperature it would still cause the enzyme to denature. Like ph, enzymes also have an optimal temperature if the temperature gets too low or too high it will denature. 

Conclusion

By performing this experiment we were able to determine the quantity of a substance in different solutions through the titration method. We also recorded the rate of how quickly the catalsye enzyme was able to convert Hydrogen Peroxide to water and oxygen gas, which helped us expand our knowledge of the importacne enzymes and how they function.

References
http://www.phschool.com/science/biology_place/labbench/lab2/intro.html

http://www.ncbi.nlm.nih.gov/books/NBK9921/

http://www.biology.arizona.edu/biochemistry/problem_sets/energy_enzymes_catalysis/01t.html

Titrating solutions

Yeast- catalyst used to start the reaction
Color of solution after being titrated 

All the solutions being set up to be timed with the catalyst 






1 comment:

  1. Nice job overall. This is going to sound picky but make sure the fonts are all the same. I realize you probably cut and paste from multiple resources but the finished product shouldn't show that. Also, your method pictures should be included with your methods and not after the resources.

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