BIOLOGY 103 FALL, 2003 LAB 4

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:

Your report should include a description of your observations relevant to identifying important characteristics of enzymes and some hypotheses about what produces those characteristics.

Iced H2O2:
5.0 sec
4.0 sec
5.0 sec

Room temperature H2O2:
4.0 sec
3.5 sec
3.3 sec
Warmed H2O2:
2.5 sec
2.5 sec
3.0 sec

(each number is a different trial)

Part III - Effects of pH on Enzyme Activity
{2.0 Buffer w/ 10ml of Hydrogen Peroxide w/ Catalase B}
It took the filter disc 2 seconds to rise to the top of the solution

1.5
1.7
1.9
2.3
3.0
3.5
4.0
4.5
5.5
6.4
6.5
6.6
6.7
7.0
7.1
7.2
7.3
7.5
7.5
7.6
7.8
8.0
8.0
8.0
8.0

In the same amount of time, 0.5 H2O2 < 1.0 H2O2 gas. Less hydrogen poroxide produces less gas (O2). The enzyme doesn't affect the final state it just affects how fast you get there.

.8
1.4
1.9
2.4
2.8
3.1
3.5
3.8
4.1
4.4
4.7
4.9
5.1
5.3
5.5
6.0
6.5
7.5
8.5
9.5

Experiment 2 Observations
Catalase B:
Run 1- 5
Run 2- 3
Run 3- 2

Catalase C:
Run 1- 6
Run 2- 4
Run 3- 5

Catalase D:
Run 1- 11
Run 2- 10
Run 3- 8

Yes, rate depends on concentration of the enzyme. The less concentrated the enzymes, the slower the rate of reaction.

- An enzyme speeds up something that is already occuring more slowly. Only affects speed, not destination.

An enzyme is a something that can speed or slow a reaction based on ph or temperature, and can increase the rate of a reaction based on concentration. Perhaps an enzyme is some sort of a living thing, because much like a plant or animal or person, if you heat it up too much, it will slow down, and if you freeze it it will slow down. This is different than what we observed about water molecules, where the extreme temperature in fact made the molecules move faster.

Catalase B (full):
1 - 3 seconds
2 - 5 seconds
3 - 5 seconds

Catalase C (1/5):
1 - 8 seconds
2 - 9 seconds
3 - 8 seconds

Catalase D (1/10):
1 - 12 seconds
2 - 12 seconds
3 - 11 seconds

A decrease in the enzyme concentration means a slower reaction rate.

What is an enzyme?: We do not know. It appears to have characteristics in common with living organisms (it has an optimal temp & pH), but it also has characteristics in common with water (H20 molecules break down the cracker, as do the enzymes in spit). The group was unable to decide whether we thought enzymes were living organisms or perhaps molecules that move faster than most and thus better facilitate the breaking down of things.

@ Chilled 4.0 4.0 4.0

@ Room Temp. 4.0 3.0 4.0

@ Warmed 3.0 2.0 3.0

These observations reveal that as the temperature rises, the reaction rate of the disc is faster therefore, taking less time to reaching the top of the solution. However, had the warmed temperature been higher, the reaction rate would have been slower and the time in reaching the top would have been greater.

In our observations, we concluded that the property of an enzyme is a catalyst that promotes the speed in which a chemical reaction takes place . In our second set of observations, we investigated the effect of temperature on the reaction rate of an enzyme.

There's an optimal temperature where the speed can reach its summit; at chilled and very warm temperatures it decreases the rate of reaction. Since, everything is falling apart, it most hold true that the enzyme will breakdown.

Data:

pH level......... Number of seconds (trial 1, trial 2, trial 3)

pH 2.0 ............... 6 , 6, 5

pH 7.4 .............. 6, 4, 5

pH 10.1 ............ 8, 6, 8

This data is not convincing that a higher pH either speeds up or slows down the process, because the data is all relatively the same. There is no gap, or significant difference, among the groups of data. From the observations collected, the hypothesis is wrong.

However, combining my data with the other group's data seems to suggest a curve; that on the pH scale the reaction time goes from slower to faster to slower. My results could have been due to human error or other small problems.

********What is an enzyme, then, and how is it related to the speeds of these reactions?

Why did the enzymes work fastest in a pH of 7.4 which is close to distilled water (7.0)? My guess was that acidic solutions would contain more enzymes to help break things down faster (such as stomach acids that are used to break down food), and also basic solutions (such as bleach) are more hamful to humans than water because they break things down faster too. So maybe enzymes balance pH. Maybe the reason that solution was a steady 7.4 pH was because it had more enzymes in it than the 2.0 or the 10.1 solutions.

But the data from the "temperature" group supports our hypothesis from last week, which says reactions happen faster in warmer temperatures, and it helped speed up the enzyme's productivity.

So my new hypothesis is that enzymes speed up reactions and balance pH towards a neutral number.

Temperature Observations:
>Chilled hydrogen peroxide: 3.67s, 4.73s, 3.59s
>Room temperature: 3.20s, 3.51s, 3.24s
>Warm temperature: 2.50s, 1.87s, 1.80s

Conclusions: The higher the temperature of the hydrogen peroxide, the greater the speed of the reaction.

What is an enzyme? : Based on our observations, we know that an enzyme is a mobile molecule that serves as a catalyst. Its function is to speed up a reaction, without changing its final state.

trial 1: 5 sec
trial 2: 5 sec
trial 3: 4 sec

chilled

trial 1: 7 sec
trial 2: 8 sec
trial 3: 8 sec

warmed

trial 1: 5 sec
trial 2: 6 sec
trial 3: 6 sec

Enzyme B (highest concentration):
Trial 1: 4 seconds
Trial 2: 3 seconds
Trial 3: 4 seconds

Enzyme C (middle concentration):
Trial 1: 13 seconds
Trial 2: 14 seconds
Trial 3: 13 seconds

Enzyme D: (lowest concentration):
Trial 1: 13 seconds
Trial 2: 15 seconds
Trial 3: 15 seconds

An enzyme is a catalyst; it is a substance with a chemical composition that speeds a reaction. In other words, adding an enzyme produces an increased rate of change in a process that would have been slower otherwise.

Part IV: Temperature

Chilled:
8
7.5
8

Room Temp:
5
5
5

Hot:
12
13
30

What is an enzyme?
We think that an enzyme is something that speeds up a process; something that acts as a catalyst to speed up a reaction. We have observed that the enzyme works at a faster rate as the concentration increases, and that there is no linear relationship between the rate the enzyme works to temperature or pH. At this point, all we can say for sure is that it is some kind of substance that speeds up a reaction at different rates depending on the concentration of the enzyme.

We measured the time it took for a filter disc soaked in Catalase B to rise to the surface with different ph buffer solutions. We repeated each trial 3 times for each ph solution.

2.0 ph buffer- 17 sec, 15 sec, 16 sec

7.4 ph buffer- 12 sec, 13 sec, 13 sec

10.1 ph buffer- 11 sec, 11 sec. 11 sec

Our results show that the rate of rising accelerated as the ph level increased. Unfortunately, this was not supposed to happen. However, we learned from the first part of the lab that an enzymes do not affect what happens, only how quickly it happens. Also, they work better at some ph levels and not others. So based on our observations, we can infer that an enzyme is alive, because it needs certain conditions to function effectively. Our results showed that enzymes just like other living organisms need a certain temperature and ph level to function best.

Does pH level affect the rate and time of a chemical reaction?

pH 2.0: 20, 24, 18 seconds

pH 7.4: 32, 24, 22 seconds

pH 10.0: 31, 31, 30 seconds

It appears as though pH level does have some effect on the rate and time of the reaction's "falling apart." Certain pH levels seem to be more effective than others in speeding up the reaction. From the data of other groups, it appears that the temperature of the enzyme affects the reaction in a similar way.

From what we have seen in the past two hours, an enzyme is a liquid that has some bearing on the rate of a reaction. It is actvated more optimally by certain temperatures and pH levels. When the rate of the reaction is increased, bubbles appear more quickly and move more rapidly, which tells us that things are falling apart faster. Also, the higher the concentration of the enzyme added to the reaction, the faster the reaction will occur.

Our hypothesis for enzyme reactions is that the more concentrated the enzyme, the faster a reaction will occur, but for pH and temperature, there is no linear relationship between acid/temperature levels and reaction rate. Rather, there are certain optimal temperatures and pH levels which cause the enzyme to work at its highest possible rate.

This goes to show that enzymes are important as catalysts to reactions in nature, but we find that their temperature does not necessarily affect the speed of their reaction. If this is the case at all times, we can say that the effect of an enzyme will be the same in all temperature conditions.

(our data is posted above, but for your convenience, here it is again. )

room temp: (5, 5, 4)

chilled: (7, 8, 8)

warmed: (4, 6, 6)

We conducted PART IV of the group experiment entitled EFFECTS OF TEMPERATURE ON ENZYME ACTIVITY.

Our observations yielded the following data:

ACTIVITY @ ROOM TEMPERATURE:

trial one... 2.25 sec
trial two... 3.5 sec
trial three... 3.5 sec

ACTIVITY @ CHILLED TEMPERATURE:

trial one... 7 sec
trial two... 5 sec
trial three... 5 sec

ACTIVITY @ WARMED TEMPERATURE:

Our results were deviant from the other experiments conducted. Our "nubbie" failed to rise in the hydrogen peroxide, giving us the time constraint of the infinite. We believe that the Hydrogen Peroxide, during the hot test segment, imposed some ill effect onto our nubbie.

THE STORY BEGINS:

It was a hot october afternoon when jlo, enor and rochelle were stirred from the dining hall and drawn mystically to the biology laboratory. We observed soft nubbies of varying thickness as they were expelled from the tweezers into solutions of different temperatures and compositions. The reaction perplexed us, however divine intervention in conjuction with the genius that is these budding scientists we have concluded:

1) Microscopic Organisms from Planet Farther infaltrated the soft glove like exterior of the nubbies causing them to scurry to the top of the solution of hydrogen peroxide. They are drawn to the nubbies because they are soooooo soft.

2) We believe that the reactants in causing these reactions are an improbable assembly of elements which when forced into the solution of hydrogen peroxide actively effect the maelstorm of motion.

Once apon a time we studied the Enzyme Concentration Effects on Rate. We got the following results:

Enzyme Concentration B:
1) 4 seconds
2) 4 seconds
3) 5 seconds
4) 4 seconds

Enzyme Concentration C:
1) 17 seconds
2) 16 seconds
3) 23 seconds
4) 16 seconds

Enzyme Concentration D:
1) 23 seconds
2) 20 seconds
3) 27 seconds
4) 19 seconds

Like a living organism, the enzyme appears to have peak performance levels at certain temperatures and pH levels. Also like a living organism, there is a limit to its possibilities (as is shown in our results). Based on this story, we think enzymes are ALIVE!!!

The end.

Hypothesis: Increasing the concentration of the enzyme peroxidase will increase the rate at which a paper slip (of a given size) will rise to the top of a beaker of H202 (of a given volume). Conversely, decreasing the concentration of peroxidase will decrease the rising rate. Concentration and rate should increase proportionally.
Concentration ~ Rising Rate.

My data were:

Concentration B - Most Concentrated
5 sec, 4 sec, 4 sec ---> avg. about 4 sec.

Concentration C - Intermediate Concentration
8 sec, 6 sec, 7 sec ---> avg. 7 sec.

Concentration D - Least Concentrated
24 sec, 17 sec, 19 sec ---> avg. 20 sec.

My data support my hypothsis. In the most concentrated enzyme, the paper rose in as little as 4 seconds -- quite quickly. On the other hand, the third and least concentrated enzyme caused the paper to take as much as 24 seconds to rise -- a very slow rate. Greater concentration induced greater rising speeds.

The function appears to be linear.

The paper slips allowed us to trace the rate at which oxygen bubbles rose, which, in turn, indicate the rate at which an enzyme reaction has occurred. [Is this true? What effects might the paper have on the accurracy of the experiment.]

What is an enzyme? Why does it increase the rate of chemical reactions (of "falling apart")?

I think an enzyme is a molecule or cluster of molecules that uses and stores energy (taken from the environment). The enzyme can then use or expend this stored energy toward a useful purpose: breaking molecules apart. In the case of 2H202 ----------> 2H20 + 02 , peroxidase speeds the natural process of dissociation (into water and oxygen) by GRABBING molecules of hydrogen peroxide and FORCING them apart, rather than leaving this breakdown to the natural but slow process of randomness.

How does an enzyme do this? An enzyme must be shaped in such a way that it can grab or latch onto, in this case, a molecule of H202. This means the peroxidase enzyme must be shaped so that it can fit or match hydrogen peroxide. Enzymes must also be capable of stretching themselves out a relatively large amount. Hence, peroxidase, having securely attached itself to the hydrogen peroxide, must STRETCH it out to the extent that the bonds of the molecules break down! The thus broken-off atoms then reform into oxygen and water, probably with the aid of different enzymes (enzymes with remarkable powers of CONTRACTION, rather than stretching, so they can stick different atoms together).

Alternatively, enzymes may be molecule clusters that possess a "saw-like" molecular compound capable of "sawing" apart other molecules' bonds every time it randomly bumps into them. Enzymes that assemble rather than disassemble molecules would have, in place of the "saw," a kind of molecular or atomic "glue" that sticks to select atoms and causes them to stick together more rapidly when they bump. However, this explanation seems unlikely because analysis of assembled molecules does not indicate the presence of special "glue" particles; so, enzymes, must do their work without using any other intermediary substance.

Whatever the means, I think enzymes speed up disocciation (and assembly) of atoms by making the atoms more likely to bump into each other and to break apart (or stick together).

Question: where do enzymes get the energy they use to put things together or break things apart? Maybe as a part of the process of respiration? Maybe that's why only living things have enzymes -- because only living things respire?


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