Download Factors Affecting the Rate of Enzyme Reaction in Liver

L. Paparella
Sullivan West
Living Environment
Factors Affecting the Rate of Enzyme Reaction in Liver
Name:_____________________________________________ Date:__________
Introduction:
All organisms rely on enzymes to catalyze chemical reactions. An enzyme is a biological catalyst that
increases the rate of chemical reaction by lowering the level of activation energy necessary to start the
reaction. Without enzymes, many of the chemical reactions that occur within living things would proceed
too slowly to be useful. Enzymes speed up these reactions by bringing the reactants into close proximity
and helping their interaction. Liver contains a specific enzyme called catalase. When hydrogen peroxide
(H2O2) is added to liver, a chemical reaction occurs which results in the products of oxygen gas (O2) and
liquid water (H2O).
Pre-Lab Questions: Use complete sentences.
1. What is an enzyme?______________________________________________________
_____________________________________________________________________________
2. What is an enzyme’s function?____________________________________________
__________________________________________________________________________
3.
What would happen if we did not have enzymes?_________________________
_________________________________________________________________________
4. What is the name of the enzyme found in liver? ______________________________
_____________________________________________________________________________
5. What is the name of the substance that we will be reacting with the liver enzyme?
________________________________________________________________________
6. What are the names and formulas of the products that you will see if the reaction is
occurring?_____________________________________________________________
______________________________________________________________________
7. If an enzyme fits with its substrate, the reaction will occur. If something is done to change
the shape of the ____________________, it will not fit the ____________________________
and the reaction will not happen. In this lab the substrate is the chemical
________________________and its chemical formula is _______________.
In this lab we will testing the effect of different factors on the enzyme’s ability to interact with the
substrate. List 4 things that you think might effect the enzyme’s ability to work properly.
_______________________________________________________________
________________________________________________________________________
L. Paparella
Sullivan West
Procedure For Part 1: Testing Surface area and Temperature
Living Environment
1. Using a blender, I pureed a chunk of chicken liver. This step will change the
______________________________ of the liver and expose more of the enzyme
________________ to the substrate________________________. Some of the puree was put
on ice and some was microwaved in water until hot. Some was left at room temperature.
2. Put your spot plate on a piece of paper. Label the top left side of the paper as Ice/Puree,
the top middle as Room /Puree and the top right as Hot/Puree. Label the bottom left side
as Ice/Chunk, the bottom middle as Room /Chunk and the bottom right as Hot/Chunk.
3. You will record your observations in the Data Table below. Add 5 drops of hydrogen
peroxide (H2O2 ) to the first spot of puree.
Record how many seconds it bubbles for = reaction rate)
Note if foam (oxygen bubbles in water) is produced quickly or slowly and use ++++ for
lots of bubbles/foam and + for very little foam= enzyme activity) If nothing happens,
record that.
4. Repeat this for the other ice cold chunk of liver and then the other set ups.
Data Table 1: Effect of Temperature and Surface Area on Enzyme Reaction Time
Ice Cold Temp /Liver Room Temp/ Liver
Hot Temp / Liver
Puree
Puree
Puree
Ice/Chunk Liver
Room Temp/Chunk
Liver
Hot Temp/ Chunk
Liver
Analysis for Part 1:
1. What is meant by reaction rate? ______________________________________
2. What are we using to measure the reaction rate? _________________________
3. How are we comparing the enzyme activity? _____________________________
4. What can you conclude about temperature and enzyme reaction rate?
____________________________________________________________________
____________________________________________________________________
5. What can you conclude about surface area and enzyme reaction rate?
______________________________________________________________________
L. Paparella
Sullivan West
Procedure for Part 2: Testing pH Conditions:
Living Environment
1. Place your spot plate on a piece of paper and label the top left side of the paper “Vinegar”,
the top middle of the paper “water” and the top right side “Borax”. Place a chunk of liver
that has been soaked in either the vinegar, water or borax in the 3 spots: left, middle and
right side of the spot plate.
2. Record the pH of each liquid soaking solution /liver sample in the data table below. Then
circle the Acid, Base or Neutral based on the pH scale reading. 1-6 acid, 7 is neutral, 8-14
is base.
3. Add 5 drops of H2O2 to the liver on the left side marked vinegar and record your
observations in the data table. (record how much it bubbles= enzyme activity = use ++++
for lots of bubbles, ++ for a few bubbles , + for very few bubbles) Record the time that the
bubbles lasted= reaction rate.
4. Repeat for the other two samples of liver that have soaked in water or borax.
Data Table : Effect of pH on Enzyme Reaction Rate
Vinegar Solution
Water Solution
Borax Solution
pH level:_______
pH level:_______
pH level:_______
Acid, Base or Neutral
Acid, Base or Neutral
Acid, Base or Neutral
Observations:
Observations:
Observations:
Analysis Questions:
1. What was the effect of the pH change on the reaction rate? Be specific. Which pH level gave
the optimal result? Which pH gave the worst result?
__________________________________________________________________________________
__________________________________________________________________________________
2. Which condition of all tested gave the fastest reaction time?
___________________________________________________________________________
3.
Which condition destroyed the enzyme completely?______________________________
4. Which condition of all tested gave the slowest reaction time?
_____________________________________________________________
5. What was the effect of increasing the surface area? Compare the chunk at room temp. with
the puree at room temp. _________________________________________________
____________________________________________________________________________
L. Paparella
Sullivan West
Additional Notes: compiled by C. Diehl
Living Environment
Hydrogen peroxide (H2O2) is a very pale blue liquid, slightly more viscous than water, that appears
colorless in dilute solution. It is a weak acid, has strong oxidizing properties, and is a powerful bleaching
agent. It is used as a disinfectant, antiseptic, oxidizer, and in rocketry as a propellant.[2] The oxidizing
capacity of hydrogen peroxide is so strong that it is considered a highly reactive oxygen species.
Hydrogen peroxide is naturally produced in organisms as a byproduct of oxygen metabolism. Nearly all
living things possess enzymes known as peroxidases, which harmlessly and catalytically decompose low
concentrations of hydrogen peroxide to water and oxygen.
Biological function
Hydrogen peroxide is also one of the two chief chemicals in the defense system of the bombardier beetle,
reacting with hydroquinone to discourage predators.
A study published in Nature found that hydrogen peroxide plays a role in the immune system. Scientists
found that hydrogen peroxide is released after tissues are damaged in zebra fish and this is thought to act
as a signal to white blood cells to converge on the site and initiate the healing process. When the genes
required to produce hydrogen peroxide were disabled, white blood cells did not accumulate at the site of
damage. Although the experiments were conducted on fish, they are genetically similar to humans and so
this may also be applicable to humans. Asthma sufferers have higher levels of hydrogen peroxide in their
lungs than healthy people and this could explain why asthma sufferers have inappropriate levels of white
blood cells in their lungs.[18][19]
http://en.wikipedia.org/wiki/Hydrogen_peroxide
On the next page complete the worksheet by labeling / identifying the enzymes/ substrates and
>>>products of various biological reactions.
L. Paparella
Sullivan West
Living Environment
Use the following terms to label the 4 diagrams below.
protease/protein >>> amino acids
Lipase/lipid>>>> glycerol and fatty acid
Carbohydrase/ starch>>>> simple sugars Catalase/hydrogen peroxide>>>>> water and oxygen
You will need to know these for your test on __________________.