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Bio 103, Lab 5, Ongoing change at larger scales: chemical reactions and "ferments"/enzymes

Paul Grobstein's picture

Not only is everything in motion but the "natural" tendency of everything , as we'll talk more about in class, is to fall apart, become more disordered. That tendency is apparent in diffusion (as we saw in the last lab), in the self-ionization of water (animation) and in chemical reactions. In this lab we will begin looking at how life processes can make use of the natural tendency to fall apart to create order. A key part of this story is that things fall apart at different rates and that "enzymes" influence that rate. We will explore the capability of enzymes to control chemical reaction rate and try and deduce characteristics of enzymes from our observations. (Instructors: see lab setup instructions).
We will begin with some basic observations implying the existence of enzymes and then explore a particular chemical reaction, the "falling apart" of hydrogen peroxide into water and oxygen gas, as it is affected by the enzyme hydrogen peroxidase:
2H2O2 ---> 2H2O + 02
Your report should include a description of your observations relevant to identifying important characteristics of enzymes and some hypotheses about what produces those characteristics.  Are "ferments"/enzymes "alive"?

Kalyn's picture

Enzyme Lab: Kalyn & Casias




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What are Enzymes: Enzymes are efficient specific catalysts.  Enzymes can speed up chemical processes that would otherwise run very slowly, if at all. Each enzyme can break down one particular compound. Enzymes are necessary for life and are present everywhere within organisms because enzymes are proteins.
 Experiment:1 The concentration of the enzyme effected the speed (rate) and amount of gas produced (end result). Our data showed a steady increase in the amount of gas produced for about six minutes and then it leveled off.
Data Found:
LEVEL                            DIFFERENCE (Start Lv. & Findings)
1.)    2.25                                        1.) .05
2.)    2.4                                          2.) .15
3.)    2.45                                        3.) .2
4.)    2.5                                          4.).25
5.)    2.6                                          5.).35
6.)    2.85                                        6.).6
7.)    2.9                                          7.) .65
8.)    3                                              8.).75
9.)    3.1                                          9.).76
10.) 3.1                                          10.).76
11.) 3.1                                          11.).76
Experiment 2: General observations learned as a class. Similar findings to experiment one with more enzyme present producing a faster breakdown rate.
Experiment 3: PH yielded a similar “U” shaped relationship as the temperature experiment. When a solution is more acidic or basic it carries a very high or very low concentration of Hydrogen ions making it difficult for the enzymes to react at a rapid speed.
Experiment#4: We found a “U” shaped curved graph effect between enzyme rate and temperature. Room temperature produced the fastest times, cold temperature yielded medium speeds and hot produced the slowest results. Enzymes only work on specific substrates so maybe heating hydrogen peroxide and the enzyme altered their structure of effectiveness towards each other. 
Data For Temperature:
Cold Trials
8 seconds
9 seconds
8 seconds
Room Temp.
7 seconds
7 seconds
4 seconds
6 seconds
Hot Trails
Final Analysis: Temperature and pH level directly effect the rate of a reaction. Temperature affects the speed of which molecules are forced into contact with each other. For our data, room temperature yielded the fastest rates of reaction. This might mean that a slight increase in temperature could yield faster results in another testing. The heated trails yielded the slowest temperatures. This suggests that an enzymes effectiveness as a catalyst is altered once it reaches a certain temperature. In this case we would guess extreme temperatures would yield the leveling off effect of a catalyst such as freezing or boiling points. We think extreme temperatures create such an effect because they probably succeed in altering the structure of the enzyme itself and therefore change the enzymes function. Similar to temperature, we think an extreme acidic solution or basic solution stop the optimal function of a enzyme. Instead, I think the room temperature or 7.0 pH are the best conditions for a enzyme to function.

ED's picture



Emily & Yashaswini
We observed what the enzyme catalase does, so that should help us determine what an enzyme actually is.
The catalase broke up hydrogen peroxide into hydrogen and oxygen. The rate at which the enzyme did this to the hydrogen peroxide changed depending on several factors (we observed how temperature affects the rate). A cold catalase B-saturated filter took 15 seconds to float to the surface of 40ml of chilled hydrogen peroxide. A room temperature catalase B-saturated filter took only 9 seconds to float to the surface of 40ml of room-temperature hydrogen peroxide. A warm catalase B-saturated filter took 15 minutes to float to the surface of 40ml of warm hydrogen peroxide. We had hypothesized that since heat (usually?) stimulates more molecular movement, it would take less time for the bubbles that resulted in this reaction between hydrogen peroxide and catalase to push the filter to the surface in the “warm” experiment. We think now that enzymes perhaps have an “optimal” functioning temperature, and the warm temp. was just too high for the reaction to “happily” occur. The heat denatures enzymes, and then most of the enzymes become the wrong shape (we think…) to properly react with the hydrogen peroxide enzymes, so the reaction happens very slowly. The rate slows down significantly.
An enzyme is something that affects the rate at which reactions take place. We also hypothesize from our experiment and another experiment performed today with pH as the changing condition that extremities, ie hot vs cold, acidic vs basic, significantly slows an enzyme's ability to speed up a reaction.


The characteristic that enzymes show for being alive is that they are improbable assemblies-- but they're only improbable assemblies of molecules/atoms. They also react to changing conditions-- but since enzyme's chemical makeup is so simple, and its chemicals are the only things it's assembled of... it is not living. We do not think they are alive.

sophie b.'s picture

sophie, jesse and keshia

Our group observed the reaction rate of enzymes at different PH levels. Our observations were as follows:

PH 2.0:
1)    51
2)    59
3)    57
PH 7.4:
1)    23
2)    27
3)    20
PH  10:
1)    21
2)    24
3)    23

We came to the conclusion that enzymes function better in less abrasive environments, as it took far longer for the filter to rise when it was placed in something highly acidic, as opposed to the neutral and low-acid content beakers.
However we also believe that because the difference between the first and second PH levels was much more significant than the difference between the second and third PH level the results do not show the extent to which enzyme reaction rate would fall in a very base ph solution.

lcorhan's picture

Laura and Kristel's Oxygen Adventure




Time (s) amount of gas (ml)


60 .6
90 .8
120 1
150 1.8
180 2
210 2.3
240 3.35
270 3.4
300 3.4
330 3.4
360 3.4
390 3.45
420 3.45
450 3.45
480 4


Then we measured the rate of reaction of three different concentrations of catalase.

Time (s)
Catalase B
Catalase C
Catalase D
Trial 1
Trial 2
Trial 3


We decided that the higher the concentration of catalase, the higher the rate of reaction. We believe this is because there are more enzymes to react with the substrate at the same time. Also we think this isn't applicable to the substrate concentration. We believe the data will be asymptotic if it is persued further because the enzyme substrate ratio will be an improper fraction, leaving no substrate behind to react to the enzymes.


Are Enzymes Alive?

We don't believe enzymes are alive because they originated from living things.





We mixed .5 ml of H2O2 with a 7.4 pH buffer and measured the gas given off by the reaction, over time.


mfmiranda's picture

Anna Chiles and Maria Miranda


Through a set of experiments involving two separate enzymes and  2H2O2, we observed the following reactions.
We created a set of observations compiling the amount of gas released by the interaction between Catalase A and 2H2O2 over time. In looking at our data in contrast with the data of the class, it was observed that the amount of 2H2O2 has an effect on the rate of interaction as well as the end products. The more 2H2O2 used in the experiment (.5 mL or 1 mL), the more gas produced by the reaction.
In a second set of observations regarding the effect of pH on the rate of the reaction (the breakdown of 2H2O2), we saw that the higher the acidity of the2H2O2  solution, the slower the reaction.
In a third set of observations regarding the effect of temperature on the rate of the breakdown of 2H2O2, we saw that the lower the temperature, the higher the rate of the reaction.
In a fourth set of observations regarding the effect of enzyme concentration on the rate of breakdown, we saw that the higher the concentration, the faster the reaction.
All in all, it was observed that an enzyme, which obviously engenders the breakdown of 2H2O2, has unique properties. Firstly, enzymes speed up the breakdown, without themselves breaking down. Secondly, the higher the concentration of the enzyme and the higher the amount of the 2H2O2, the faster the rate of reaction. So, the amount of both enzyme and solution directly affects the speed at which the two interact. Puzzling, though, are the observations which prove that acidity and heat do not speed up the rate of breakdown. We have concluded that the more neutral the pH and the less affected the temperature (closer to room temperature), the faster the reaction. So, it seems that the best conditions for an enzyme to break down 2H2O2, are those that are the most natural. Our observations would suggest that enzymes are not alive.


Karina G's picture

Lab 5

Heather Lewis, Karina Granadeno


The effects of temperature on enzymes


Hot Temperature

1st trial- 1:08 minutes

2nd trial - 1:08


Room Temperature

1st trial- 0:08 seconds

2nd Trial- 0:09


Cold Temperature

1st Trial- 0:10 seconds

2nd Trial- 0:09


From experiment 2 we can conclude that hotter substances break down molecules more slowly, because we can see that it took longer for the disc to rise to the top in the warm peroxide than in the room temperature or cold peroxide. A possible explanation for this is that more movement of particles makes it more difficult for the catalyst to break down the substance. By heating both the catalase B and the peroxide, both substances had particles that were moving randomly and more quickly. Therefore, it was more difficult for the particles to connect with each other in the constant motion, and more difficult for the enzyme to begin the breakdown of the hydrogen and oxygen atoms. An increase in pH would make this even more difficult, because the increase in hydrogen atoms would mean that the oxygen atoms would be harder to reach. Hydrogen atoms would block the catalase from the oxygen atoms, making breakdown more difficult.




JJ's picture


Through our observations we have concluded that an increase in enzyme concentration will speed up the breakdown process further. The higher the temperature, the slower the rate of enzyme activity, the lower the temperature the faster the rate of enzyme activity. This is due to the fact that enzymes are living organisms, and organisms tend to function best at intermediate levels. This is true when observing different pH levels and their effect on enzyme activity. The lower the level of pH, the faster the rate of enzyme activity; the higher the level of pH, the slower the rate of enzyme activity.

-Michelle, Janice, Debbi, JJ, and Lili


Size of bubble at different time intervals (in 30 second intervals):

.5 ml, 2, 3.2, 3.4, 4.1, 4.5, 4.7, 5.7, 6.2, 6.3, 6.3, 6.5, 6.7, 6.7, 6.7

Enzyme concentration times:

Catalase "B" (in seconds)

Trial 1: 9.9

2: 6.7

3: 8.2

Catalase "C" (in seconds)

Trial 1: 21.5

2: 20.3

3: 20.6

Catalase "D" (in minutes)

Trial 1: 1:15

2: 0:54

3: 1:22

-JJ and Lili

JyL's picture

Lab 5

Effects of pH on enzyme activity

-2.0 pH buffer:

1. 25.58 sec

2. 31.41 sec

3. 29.05 sec

-7.4 pH buffer:

1. 18.91 sec

2. 18.01 sec

3. 17.68 sec

-10.4 pH buffer:

1. 18.25 sec

2. 17.59 sec

3. 15.21 sec

-janice lee, debbi chin, michelle han
(for explanation please see post by lili, jj, janice, debbi and michelle)


Terrible2s's picture

Lab with Herman Marcia, Jen Pierre, and Terrible2s

Having studied enzymes and observed their behavior in regards to enzyme concentration, temperature, and pH, we have concluded a few major ideas:

1.  They work as a catalyst in that they break organisms down without deconstructing themseleves.

2. Enzymes are specific too particular materials in that there will be certain enzymes best suited-or more suited- to break down an organism more than another type of enzyme.

3. The more enzymes, the quicker they can break the organism down because they increase efficiency.

4. It seems because of the u-shaped temperature and PH depressions that enymes work most effectively and/or exist at neutral temperature (i.e. 65 degrees or room temp) and a neutral PH level (i.e. neither too acidic nor too basic)

jmstuart's picture

 I. Effect of Substrate

 I. Effect of Substrate Level

For 1 ml of Catalase A, we took measurements every 30 seconds of the amount of gas being produced in cm.

Results: .25, .75, 1.5, 2.4, 3.4, 4.75, 5.5, 5.75, 6, 6.5, 6.5, 6.5

These results show that the enzyme was effective for a certain amount of time before the levels plateaued, and the class results show that if less substrate is used, it does not produce as much gas and plateaus sooner.

II. Effect of Enzyme Concentration

For each concentration of catalase, we timed how long it took for a filter soaked in each type of catalase to rise to the top of a beaker filled with hydrogen peroxide. 

Catalase B: 5 sec, 4 sec, 5 sec

Catalase C: 27 sec, 16 sec, 16 sec

Catalase D: 62 sec, 135 sec, 105 sec

As the concentration of the enzyme decreased, the time it took to float increased. This, along with our classmates results, leads us to believe that more enzymes leads to faster reactions. 

Other results include a U-shaped graph for both temperature and pH levels.

To explain the phenomena of how the enzyme itself is not destroyed in the reaction, we predict that the enzyme is not actually a part of the reaction itself, but instead affects the substrate involved in the reaction in order to increase the speed. (It acts as a catalyst.) This may be done through changing the activation energy needed for the reaction to occur, or by changing the shape or destabilizing the substrate in some way that makes it more likely to break down. Enzymes must be material-specific because they do not seem to be corrosive to all substances. Also, if our theory is correct, every reaction has a different activation energy necessary for it to occur. In terms of temperature and pH, there seems to be a very specific range for this enzyme to function. This indicates that it may be an organic substance, such as a protein. This means that at a certain pH or temperature, qualities of the enzyme (ex. shape) may alter to the point that it is no longer effective. 


David Richardson and Julia Stuart