In this lab, we studied the activity of an enzyme that is found in fruits and vegetables called catecholamine or cathode oxides. An enzyme is a protein molecule that is a catalyst. Cathode oxides is the enzyme in fruits and vegetables that turns them that undesirable brownish color; also commonly referred to as bruising or bruised. When walking through your regular grocery store and you find yourself in the produce section, what is it that you look for before putting that produce in the bag for weighing?
The size, the smell, the color? Most of us would have to say that if they grabbed an apple that had a bruised body, they would return that apple to the pile in search for that perfect skinned apple. This is why studying cathode oxides is so important! Lees take a kick at population numbers and why cathode oxides is so important with the increasing number of people living on Earth. In 2010, the global population was estimated to be around 6. 9 billion people (1). From 2008 to the end of 201 1, the number of hungry families in Washington grew from about 88,000 to 163,000… In 2011, 15. Percent of Washington households reported some level of food insecurity, which means they regularly struggle to get enough food for their families, according to the USDA. ” (2). With an increase like that in the amount of people struggling to feed themselves, how do we think it’s going to be when the expected population growth on Earth jumps to 9. Billion in 2050 (1 This is why studying cathode oxides is so important. According to a I-J news article back on September 19, 2013, “Up to two-fifths of a crop of fruit or vegetables can be wasted because it’s “ugly’ Produce grown in the UK that does not meet detailer standards on size or shape or is blemished is often used for animal feed or simply ploughed back into the ground even though it is edible, with as much as 40% of a crop rejected. ” (3). Up to 40%!
With people going hungry all over the world, if we were able to figure out how to reverse cathode oxides or even halt it for a period, we would be able to have those fruits and vegetables out longer with purchasers willing to buy them because they still hold their “pretty” appearance. Before I get into more about the actual experiments done in the lab, let me explain in a little more detail about enzymes. Enzymes speed up chemical reactions and those chemical reactions then either consume or change the enzyme itself.
Enzymes structures are three-dimensional that are built up by at least one or more peptide bonds that form what is known as an active site. The active site is where the substrate (cathode in this experiment) will go and attach. Many things such as changes in temperature and changes in pH can affect the structure of the active site which will affect the rate of reaction of how the enzyme contributes. Please see below for the chemical reaction done by cathode excised: (4) This reaction is what causes the fruits and vegetables to brown or looked bruised.
In the middle you see where the cathode oxides (remember: it is the enzyme so that means it speeds up the reaction) comes into play. Cathode oxides are found in the cytoplasm of the fruits and vegetables. When cathode oxides is exposed to oxygen, it turns the fruits and vegetables brown. Remember how above I stated that many things can change the structure of the active site, such as pH? Well as it would have it, all enzymes are affected by changes in PH. Not only can it change the shape of he structure of the enzyme, but it can also change the shape or charges of the substrate as well.
That can make it so the substrate is unable to bind to the active site making it unable to go through catalysis. So they work in what’s called the “lock and key” manner with the substrate. When the optimum pH level of an enzyme is met, it allows it to lock with the substrate to form the catalyst. The optimum pH is where the enzyme is the most active. Butts because one enzyme is most active at a certain point, doesn’t mean that other enzymes are the same. In fact, the optimum pH can differ greatly from enzyme to enzyme. Please look to the left for what optimum pH will look like on a graph (5).
As you can see, at the highest point of the bell curve is where the optimum pH of that enzyme is. The optimal pH allows the reaction between the enzyme and substrate to continue on. My hypothesis for this lab, Exercise C: Effect of pH on the Action of Cathode Oxides: The rate of the cathode oxides activity levels will be altered by the change in pH levels. I believe this is so because as stated above, pH has a great effect on the structure and function of the enzyme itself. The rate of absorption will tell me whether my hypothesis is correct or not.
My null hypothesis for this lab, Exercise C: Effect of pH on the Action of Cathode Oxides: The rate of the cathode oxides activity will not change due to the different pH levels. Rather it will stay the same throughout. Methods: was in a group of four people: Kari Series, Kelsey Heinz and Deborah Thermal. For our Lab 4 Enzyme activities, we were going to be using potato juice (enzyme) and cathode to resemble the natural acting potato and catecholamine reaction. We followed Exercises A & B as instructed in the Lab Manual for Lab 4 Enzymes. When it came to Exercise C, we were assigned HA.
In order for us to be able to get all the information down, we split up the tasks for this exercise. Deborah and myself were the readers and recorders of the absorbency rates. We used a “blank” tube to get the absorbency level at O on the spectrophotometer at O seconds to get the experiment off correctly. Kelsey was the person who would take the test tube in and out of the spectrophotometer on Sari’s instruction as she was the one doing the 10 second timing. When Kelsey pulled the test tube out that held our pH, she inverted the tube twice before sticking it back into the spectrophotometer.
We did this process for a total Of 120 seconds and recorded the readings. Results: Table: Absorbency vs.. Time- Enzyme Activity ; Thursday’s Lab Class Time (sec) pH pH pH (replicate) phi -0. 01 10 I . 420 0. 206 0. 694 -0. 070 0. 380 0. 650 20 1 . 750 0. 356 0. 820 -0. 033 0. 500 644 30 2. 050 0. 430 0. 880 -0. 001 0. 538 0. 656 40 2. 340 0. 486 0. 940 0. 013 0. 586 0. 642 50 2. 660 0. 550 0. 960 0. 031 0. 614 0. 628 60 2. 940 0. 616 1 . Oho 0. 050 0. 648 0. 620 70 3. 150 0. 680 1 . 030 0. 074 0. 676 80 3. 400 0. 718 1 . 070 0. 1 33 0. 700 0. 606 90 3. 700 1 . 025 1. 110 0. 148 0. 728 0. 596 OHIO 3. 00 1 . 090 1. 140 0. 151 0. 72 110 4. 100 1. 160 1. 180 0. 176 0. 792 0. 578 120 4. 200 1 . 250 1 . 210 0. 194 0. 800 0. 570 color (after 120 seconds) deep rust deep rusty brown rusty brown orange rusty pink-brown The table above not only shows my groups pH level recordings, but also the rest of the groups recording as well. On the bottom of the table you will see the color of which those groups determined the contents in their test tubes to look like. While the amount of contents, absorbency readings and timing are all quantitative observations, the color inside the tube was a qualitative observation.
All pH levels increased in absorbency except for PHI O. Because most of the pH’s absorbency increased with time, that shows that the reaction between the enzyme and the substrate are continuing and moving forward. Graph: Absorbency vs.. Time- Enzyme Activity Thursdays Lab Class: In this graph above, you can visually see the dramatic increase in absorbency in pH while pH (replicate) has the lowest level of absorbency. Also take not though, while you cannot see it very well on this graph, phi has an absorbency that started out strong, but decreased as time went on.
In order for us to determine the reaction rate, we needed to look at the information elected from the experiment that is listed on the first table of this report. I also created separate tables for each pH level for my own guidance. In the mathematical equation, you use y=mix+b. In this experiment, b is equal to O, so really you have y=mix. In order to find the slope or rather the reaction rate, we needed to do the rise/run=ran which meant we needed to find the change in y and the change in x. The equation at this point would be ye-ye /xx-xx.
Because yell and XSL are both O, you simply had to do ye/xx. In a simpler explanation, you take the 10 second absorbency and divide it by 10. That is owe the rate of reaction numbers above came to be. This table includes all the pH data collected. For a view of what this looks like on a graph, please see below. Please take note that due to my excel, was not able to make it a curve table as it should have been. Rather it is a table with strict points. You can see just the same the high points and low points that you would see if it was a bell curve table.
Graph: Reaction Rate vs.. PH with all pH data: This graph shows that the absorbency level throughout the pH’s goes down the higher the pH, meaning the lower the acidity. Though the information resented is all over the board which to me is telling me that most likely, there were errors in the experiment. I will discuss those further in the discussions and conclusions part of this report. There are a couple of outliers that believe could be taken out in order for the data to be more correct. For those, would choose to take out pH and pH (replicate).
The reason for pH, even though it was the pH that my group was assigned to, it was significantly higher than the rest showing it to be one of the biggest outliers. Then am going to take out pH (replicate) because first, it is a negative umber, and second, it is the second largest outlier. Updated Table: Reaction Rate vs.. PH- Excluding pH & pH (replicate)- Thursday’s Lab Class Rate of Reaction PH 0. 0206 0. 0694 0. 038 PHI o 0. 065 An updated graph for the table above is below: This shows a more linear graph with taking out those outliers.
This changes the findings though as well from saying absorbency is decreased with a higher pH to the absorbency is increased with the higher PH. Discussion and Conclusion: The absorbency for all by phi increased as time passed; Though there wasn’t a direct trend as to the higher the pH level the more it was absorbed or visa versus. In my hypothesis stated that I believed that the rate Of cathode oxides activity will change with the different pH levels. The findings supported my hypothesis because it showed that there was a significant change throughout the pH levels.
The higher acidic pH’s, such as pH and pH, ended up having the greatest absorbency, though pH was close behind. PHI O actually had an absorbency that decreased as times passed. pH absorbency rate was significantly higher than the rest of the class which leads me to believe that we did something incorrect or that something went wrong in our results. While I thought we took special care when putting the intents into the tube and made sure that everything was working correctly, still many things could have gone wrong.
We could have had air bubbles or a dirty cavetti that would not let the light to penetrate through, there could have been measuring errors, missed timings, cross contamination of solutions, or even the spectrophotometer could have been set incorrectly or it could have been drifting causing the incorrect information. So like I said, many things could have gone wrong. It seemed that a lot of the information from the other groups was also incorrect. It didn’t show an optimum curve at all with the pH’s which is the first indicator.
So from there I went ahead and took out the two largest outliers which was pH and pH (replicate) to try and get more of that curve and a more accurate finding. While it came closer to linear and more of a curve, still believe that the findings in the class with the groups were mostly incorrect So I would suggest that this experiment be repeated to get better and more accurate results. Because I excluded pH and pH (replicate) from my findings, I would have to say that pH was the most effective. It is more in the safe range for the pH’s and is less acidic than HA and pH, which could mean that it allows for easier absorption.
But it is not so low on the acidic scale that the rate of reaction is just too minimal. Believe that this is important because all living organisms have an acceptable pH level that works for them and doesn’t.