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Temperature's Effect on the Production of Oxygen From Yeast and Hydrogen Peroxide

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Temperature's Effect on the Production of Oxygen From Yeast and Hydrogen Peroxide Planning
Aim
---

My aim is to discover how temperature effects the production of oxygen
from yeast and hydrogen peroxide. I will mix yeast with hydrogen
peroxide and use an upturned measuring cylinder to measure how much
oxygen is produced. To find out how much hydrogen peroxide and yeast I
will use, I will carry out pre-tests. This will also aid accuracy of
the final experiment by uncovering potential flaws in the method.


Hypothesis and Theory
---------------------

There are many ideas to suggest that the change in temperature will
cause an increase of respiration in yeast. Yeast is a single cell
fungus made up mostly of protein, which has been use for its
applications in fermentation. Yeast, after activation creates the
ferments carbon dioxide and ethyl alcohol by secreting the enzyme
zymase (a complex of 12 enzymes) in the yeast, which acts on simple
sugars such as glucose. The alcohol produced has been used in making
wines and bears and the carbon dioxide produced has been used in
baking as it gets trapped in the dough and causes it to rise.

Enzymes are catalysts which speed up reactions, they are made from
protein and are specific as to which substrate they work on. Enzymes
basically work due to the lock and key theory, where the substrate
substance (the key) fits into the active site on the enzyme and they
bind together, the reaction takes place and the substrate unlocks to
form one or more substances leaving the enzyme ready to perform the
binding again. An enzyme can only bind with a substrate that fits the
shape of the active site unique to that kind of enzyme. The induced
fit theory states that the substrate cannot bring about catalysis and
the reaction itself, but the active site, when it comes into contact
with the substrate slightly changes its shape to form an effective fit
and arrangement of catalytic groups on its surface, which brings about
the catalysis reaction. To display this, think of a hand in a glove
where the hand acts as the key and substrate, inducing a change in the
shape of the glove, which acts as the enzyme. When some substrate
substances induce a fit with the enzyme, the enzyme may not be able to
accept some other substrates.

Yeast has to make energy, stored as AP to carry out cellular
functions. To do this they can respire both aerobically when there is
plenty of oxygen, but where oxygen is short, they respire
anaerobically; which makes them partial anaerobes. This produces less
energy, but keeps the yeast alive. Pyruvic acid has to be broken down
in respiration when formed by the breaking down of glucose molecules.

Kinetic theory states that, with an increase in temperature, the rate
of reactions will increase. This is due to the increase of speed of
the particles, brought about by the extra energy given to them by
heat. Faster particles will bring about more particle collisions and
so the reaction will take place faster. Enzymes are sensitive to
temperature changes up until a certain temperature and will increase
in their reactivity also. The reactions that take place in the enzymes
will be quicker and so will create more of their products. Enzymes are
sensitive to temperature up until a certain temperature where the
shape of the active site is altered drastically, so much so that
binding hardly ever takes place. This is called denaturisation.

Catalase is a common enzyme found inside many cells and tissues. It
destroys hydrogen peroxide, which is a poison if it is allowed to
build up inside the cells. The reaction is:

Hydrogen peroxide ---> Water + Oxygen

The enzyme is often used, as it is quite easy to see the froth caused
by the oxygen being given off. This means that you can monitor the
rate of the reaction quite easily. More accurate experiments will
actually collect the oxygen and measure its volume.

With reference to my theory, I predict that the rate and speed of
respiration of glucose by yeast will increase with temperature rise,
up until a certain point where the enzyme used and secreted by the
yeast will become denatured and cease to function, reducing the rate
significantly. This is explained through kinetic theory, yeast
respiration, the nature of enzymes and Catalase.

I will carry out two pre-tests. The equipment I will use:

1 Water Bath

1 Test Tube

1 Upturned Measuring Cylinder

2 Clamps

1 Piece of Rubber Tubing connected to a Bung

0.1g of yeast

3ml Hydrogen Peroxide

A Balance (to weight the yeast)

A Pipette

Stop Clock

It will be set-up as follows:

Possible variables I could use:

Temperature

Amount of H2O2

Amount of Yeast

How the variable will affect the final result:


TEMPERATURE
-----------

Temperature of the experiment will have a great effect on the results
as explained by kinetic theory. Temperature will affect the rate of
the yeast's respiration. I shall keep the temperature of the mixture
and water bath under control by using a thermometer and checking it
constantly. I shall keep swirling the thermometer to keep the heat
distributed.

AMOUNT OF H2O2

The amount of hydrogen peroxide will affect the results also, as more
H2O2 means that there are potentially more products, which would make
the results accurate or the experiment fair. The H2O2 will be measured
out in a small measuring cylinder each time.

AMOUNT OF YEAST

The amount of yeast is crucial, more yeast means more H2O2 will be
respired and more products created. An imbalance will upset the
results. The amount of yeast will be weighed out on an accurate
balance each time.

In my experiment, my controlled variables will be the amount of yeast
and H2O2. The independent variable will be the temperature and the
dependent variable will be the amount of oxygen produced.


PRE-TEST RESULTS

Temperature: 20°C

Time (minutes)

Oxygen Produced (cm3)

1

2.5

2

5

3

9

4

13

Temperature: 55°C

Time (minutes)

Oxygen Produced (cm3)

1

17

2

19

3

20

4

20


Method

In my final experiment I will use the same method as I used for the
pre-tests. I will set up the equipment as I did before and use the
same equipment. When the hydrogen peroxide is in the test tube, I will
start the timer, the bung will go on and the H2O2 will react with the
yeast and produce oxygen which will travel up through the bung,
through the tube and go into the upturned cylinder and displace the
water, which goes out through the bottom. After the experiment is
complete, a new test tube will be used. The experiment will be carried
out ten times: twice at each of the following temperatures: 20°C,
30°C, 40°C, 50°C and 60°C.

Obtaining

RESULTS

Temperature: 20°C Test 1

Time (minutes)

Oxygen Produced (cm3)

1

2

2

6

3

11

4

13

Test 2

Time (minutes)

Oxygen Produced (cm3)

1

2.5

2

6

3

10

4

12

Temperature: 29°C Test 1

Time (minutes)

Oxygen Produced (cm3)

1

4

2

12

3

13

4

13

Test 2

Time (minutes)

Oxygen Produced (cm3)

1

6

2

8

3

12

4

13

Temperature: 39°C Test 1

Time (minutes)

Oxygen Produced (cm3)

1

9

2

11

3

12

4

15

Test 2

Time (minutes)

Oxygen Produced (cm3)

1

8

2

12

3

14

4

15

Temperature: 48°C Test 1

Time (minutes)

Oxygen Produced (cm3)

1

7

2

11

3

13

4

13

Test 2

Time (minutes)

Oxygen Produced (cm3)

1

7

2

11

3

13

4

14

Temperature: 59°C Test 1

Time (minutes)

Oxygen Produced (cm3)

1

16

2

19

3

21

4

21

Test 2

Time (minutes)

Oxygen Produced (cm3)

1

17

2

20

3

21

4

22

I have ensured that my results are as accurate as possible by
controlling all the variables stated in my planning section. I also
took care when using the equipment so as to retain continuity
throughout the experiment. For this, I checked everything was set up
correctly at each reading and prepared my solution in the same way. I
did not prepare a batch of solutions as this would have given some
more time to acclimatise and more time to react and respire, changing
the conditions.


AVERAGES

Temperature: 29°C

Time (minutes)

Oxygen Produced (cm3)

1

2.25

2

6

3

10.5

4

12.5

Temperature: 39°C

Time (minutes)

Oxygen Produced (cm3)

1

5

2

10

3

12.5

4

13

Temperature: 48°C

Time (minutes)

Oxygen Produced (cm3)

1

7

2

11

3

13

4

13.5

Temperature: 59°C

Time (minutes)

Oxygen Produced (cm3)

1

16.5

2

19.5

3

21

4

21.5

To carry out a safe experiment, I wore goggles. I made sure not to
spill any H2O2 and carried the jugs of hot water in two hands to avoid
dropping it.

Analysis

My results show that if you increase the temperature, the rate of
reaction increases. BUT, as you get to a higher temperature, the
reaction takes place in the first minute and doesn't react much in the
next three, as seen in the experiment using water of the temperature
59°C. This is the denaturisation of the yeast's enzymes. The results
prove my theory and hypothesis as follows:

Enzymes are catalysts which speed up reactions, they are made from
protein and are specific as to which substrate they work on. Enzymes
basically work due to the lock and key theory, where the substrate
substance (the key) fits into the active site on the enzyme and they
bind together, the reaction takes place and the substrate unlocks to
form one or more substances leaving the enzyme ready to perform the
binding again. An enzyme can only bind with a substrate that fits the
shape of the active site unique to that kind of enzyme. The induced
fit theory states that the substrate cannot bring about catalysis and
the reaction itself, but the active site, when it comes into contact
with the substrate slightly changes its shape to form an effective fit
and arrangement of catalytic groups on its surface, which brings about
the catalysis reaction. To display this, think of a hand in a glove
where the hand acts as the key and substrate, inducing a change in the
shape of the glove, which acts as the enzyme. When some substrate
substances induce a fit with the enzyme, the enzyme may not be able to
accept some other substrates.

Yeast has to make energy, stored as ATP to carry out cellular
functions. To do this they can respire both aerobically when there is
plenty of oxygen, but where oxygen is short, they respire
anaerobically; which makes them partial anaerobes. This produces less
energy, but keeps the yeast alive. Pyruvic acid has to be broken down
in respiration when formed by the breaking down of glucose molecules.

Kinetic theory states that, with an increase in temperature, the rate
of reactions will increase. This is due to the increase of speed of
the particles, brought about by the extra energy given to them by
heat. Faster particles will bring about more particle collisions and
so the reaction will take place faster. Enzymes are sensitive to
temperature changes up until a certain temperature and will increase
in their reactivity also. The reactions that take place in the enzymes
will be quicker and so will create more of their products. Enzymes are
sensitive to temperature up until a certain temperature where the
shape of the active site is altered drastically, so much so that
binding hardly ever takes place. This is called denaturisation.

Catalase is a common enzyme found inside many cells and tissues. It
destroys hydrogen peroxide, which is a poison if it is allowed to
build up inside the cells. The reaction is:

Hydrogen peroxide ---> Water + Oxygen

The enzyme is often used, as it is quite easy to see the froth caused
by the oxygen being given off. This means that you can monitor the
rate of the reaction quite easily. More accurate experiments will
actually collect the oxygen and measure its volume.

The graph shows a trend: if the temperature is increased, the reaction
is faster- up to a certain point.

Evaluation

I have found that as I increased the temperature of the yeast
solution, the rate of respiration of the yeast increased to a certain
point where, as the temperature rose to a certain level, (in my case
about 59°C) the rate of respiration eventually cut off.

My hypothesis and prediction can e backed up with the findings; from
looking at my results and graphs you can see the rise and fall of
respiration. Thus my hypothesis and prediction are shown to be present
and displayed to a large extent. They are explained due to the
theories of enzyme-substrate with lock and key and kinetics. Where
these meet is when kinetic theory states that an increase in
temperature means more particle collisions between reactants and so a
faster rate of reaction; and in enzyme-substrate where the enzyme is
sensitive to heat, and about a certain temperature, the active site
will begin denaturing, so slowing and eventually stopping the
reaction. This will give an area where the rate of respiration drops
off and goes to nothing instead of a precise cut-off point. These both
apply to my experiment and were described in my planning section.

My results were fairly close, which means they are fairly reliable. If
there are any inaccuracies, they can be explained. The yeast was in
little balls, if it was completely crushed to a powder the surface
area would be increased therefore putting the bung on. If the yeast
wasn't left in the test tube in the heated water, the yeast might not
acclimatise to the selected temperature before the hydrogen peroxide
was added. This would mean the temperature is not affecting the
temperature. All three of these could make the experiment inaccurate.

To make sure that the results were as reliable as I could make them, I
calculated the mean of two results at each interval when dealing with
the rate. The obvious anomalous result is at 3 minutes with
temperature 39C, this could be due to the afore mentioned flaws in the
method. I took all possible precautions to make the apparatus used to
be reliable and give good values do I think the slight unreliability
was caused by the preparation of the solution and the unpredictability
of how the reaction went that came with it. To obtain more reliable
results I would want complete continuity with preparations, maybe
arranging sets of substances to create multiple solutions beforehand
or preparing them but not actually activating the yeast so as to
prevent any getting a head start over the others. This would ensure
that all the preparations are the same and would give continuity. This
would help give more reliable results throughout.

If I were to further investigate this experiment and my results, I
would probably want to calculate the point where the enzymes begin to
denature for respiration in yeast. I could also examine the change in
rate between the intervals to determine validity and continuity, also
running them through maybe more intricate calculations involving log.
At this stage, I shouldn't think there is too much more I can do. I
think it would be interesting to vary the amount of H2O2 as an
extension.

How to Cite this Page

MLA Citation:
"Temperature's Effect on the Production of Oxygen From Yeast and Hydrogen Peroxide." 123HelpMe.com. 24 Oct 2014
    <http://www.123HelpMe.com/view.asp?id=121896>.




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