My Classroom Material 173 - BIOLOGY JUNCTION

Campbell Problem 9

Molecular Genetics Problem 9 9. What pattern of inheritance would lead a geneticist to suspect that an inherited disorder of cell metabolism is due to a defective mitochondrial gene?

The disorder would always be inherited from the mother because the mother’s mitochondrial gene is the only one that survives when the zygote is formed. The gamete from the mother contains all the information. The head of the father’s sperm is the only part that survives during fertilization. The tail of the sperm containing the male’s mitochondria (an their genes) is lost when the zygote begins development. Thus it is only from the mother that the disorder can be inherited.

Do Brain Cells Run Out of Gas?Within each cell reside hundreds of tiny gas stations known as mitochondria. These essential organelles generate a large share of the fuel, a molecule called ATP, that cells use to power their biological machinery. There’s a suspicion, admittedly controversial, that problems with these energy-supplying mitochondria contribute to the progression of age-related neurodegenerative illnesses such as Alzheimer’s, Parkinson’s, and Huntington’s diseases, says Douglas C. Wallace of Emory University School of Medicine in Atlanta. In 1993, Wallace and his colleagues reported on comparisons of the mitochondrial DNA of Alzheimer’s patients and that of people without Alzheimer’s, who served as controls. This genetic material, which contains all the instructions necessary for mitochondria to function and replicate, is independent of the DNA found in a cell’s nucleus. Wallace’s group discovered that a particular mutation in mitochondrial DNA showed up in more than 5 percent of Alzheimer’s patients but in less than 1 percent of a random group of people with-out the disease. Studies on animals support the importance of mitochondria in brain disorders. When investigators destroy mitochondria or inhibit the activity of enzymes crucial to mitochondrial function in rats or mice, the rodents develop behavioral or physical attributes of Alzheimer’s, Huntington’s, and Parkinson’s diseases. &emdash; J. Travis

Science News: Aug. 5 • Vol. 148, No. 6

BACK

Carbon Dioxide Use in Plants

Do Plants Consume or Release CO2?

Introduction

The rate of photosynthesis can be determined by measuring the rate of production of sugar or oxygen or by measuring the rate of decrease in carbon dioxide concentration. A common aquarium plant called, Elodea, can be used to show fast carbon dioxide is being removed from the water in which the Elodea is submerged.

6CO2 + 12H2O + light energy —> C6H12O6 + 6O2 + 6H2O

In this lab, you will use phenol red as an indicator to show whether CO2 is being consumed or produced in a reaction. It is well known that in the presence of light, plants perform photosynthesis. At the same time, plants are also performing cell respiration. To demonstrate this, we will determine whether CO2 is consumed or produced as Elodea is placed in either a light or dark environment. The change in CO2 will be detected by the pH indicator phenol red. Phenol red is yellow under acidic conditions (high H+ ion concentration), pink to magenta under basic or alkaline conditions (low H+ ion concentration), and orange under neutral conditions. A change in the amount of CO2 will cause a directly proportional change in H+ ion.

If the CO2 concentration decreases, the H+ ion concentration will also decrease, and the solution will change to pink, becoming basic.

If the CO2 concentration increases, the H+ ion concentration will also increase, and the solution will change to yellow, becoming acidic.

Neutral solutions of phenol red will be orange.

Materials:

phenol red solution, 4 sprigs of Elodea, soda straw, 4 test tubes, labeling marker, 100 ml graduated cylinder, beaker, aluminum foil

Procedure:

Create a solution of phenol red by adding concentrated phenol red to about 100 ml of water in a beaker. The phenol red may change color as a result of adding water (depending on how acidic your tap water is). Your goal is to make your solution a neutral orange color. You can do this by gently blowing into the solution with a straw.
Label 4 test tubes 1, 2, 3, and 4.
Once you have the solution at an orange color, transfer it to 4 test tubes (they should be filled about 2/3 full with your orange solution).
Place a cut piece of Elodea (cut end up) into tubes 2 and 4 and tightly cap.
Test tubes 3 and 4 will not have Elodea. Cap and then cover these tubes with aluminum foil so no light can enter.
Place tubes 1 and 2 in bright light.
Place tubes 2 and 4 in the dark.
After 24 hours, uncover and examine all 4 test tubes and record the results.

Data:

Test Tube #	Contents of Tube	Initial Color	Final Color
1
2
3
4

Conclusion:

1. What test tubes served as the controls in this experiment. Why?

2. What was the dependent variable?

3. Do you think there would have been any change in any of the test tubes if they were left for 48 or 72 hours? Explain.

4. Describe and explain what happened in the test tubes.

5. Why did the color change occur?

6. Where does the carbon dioxide that is removed from the solution go?

7. What other process goes on in plant cells that requires oxygen and produces carbon dioxide?

8. What was the purpose in tightly capping all four test tubes?

Catalase Bi Sample Lab 2

Enzyme Rate of Reaction for Catalase

Introduction:
Life would not be possible without chemical reactions. Chemical reactions are responsible for speeding up the process. A chemical reaction is the process of breaking chemical bonds, forming new bonds or both. The four things that can speed up a chemical reaction is heat, increasing the concentration of reactants, decreasing the concentration of products, and enzymes. Enzyme is a catalase, most the time a protein. Enzymes can control the rate of a reaction, and they also lower activation energy. Enzymes are important in regulating chemical pathways, synthesizing materials needed by cells, releasing energy, and transferring information. Enzymes are involved in digestion, respiration, vision, movement, and thought. There are several things that can affect the function of enzymes like temperature, the pH, and the amount of reactant or product. Simple cells may have as many as 2000 different enzymes, each one catalyzing a different reaction. In this particular lab, your hands act as the enzyme “Catalase”. This enzyme, which is found in your cells, splits hydrogen peroxide, a byproduct made by your cells during cellular respiration, into water and oxygen.

Hypothesis:
If time is increased, then more hydrogen peroxide molecules will be split into water and oxygen

Materials:
The materials used in this lab were pencils, scissors, envelope, 100 paper hydrogen peroxide molecules, and a watch with a second hand so that a person would be able to keep time for the person tearing the strips.

Methods:
Take a paper template and cut out 100 hydrogen peroxide molecules. Place the cut out pieces into an envelope. Then have a person act as a catalase and take one piece of the paper molecules out of the envelope at a time and rip it in two and place the pieces back into the envelope. Have a person hold the envelope person, while another student keeps track of the “tearing” time intervals (10, 20, 30 ,60, and 60 seconds). Count how many molecules are ripped at the end of each time interval and record this number in your data table. When all time intervals and counts are completed, use the formula below to figure the reaction rate for catalase. Record this rate in your data table.
M2 – M1 = reaction rate
T2 – T1

Results:

Time in seconds	Ripped Hydrogen Peroxide Molecules	Rate of reaction
0-10	3	.3
10-30	10	.35
30-60	24	.47
60-120	63	.65
120-180	124	1.02

1. What is an enzyme? What are its functions in living things?
Enzymes are proteins in living systems. Enzymes can control the rate of a reaction, and they lower activation energy.

2. Name several things things that can affect the function of an enzyme?
Temperature, the amount of reactant or product and the pH.

3. Write the chemical equation for the breakdown of hydrogen peroxide by the enzyme catalase.
hydrogen peroxide + catalase yields water + oxygen

4. An enzyme’s efficiency increases with greater substrate concentration, but only up to a point. Why?
all of the active sites of the enzymes become filled with hydrogen peroxide molecules

5. If you were allowed to continue this lab and rip hydrogen peroxide molecules for 240 and 300 seconds. What would happen to the rate of reaction and why would this happen?
It would increase.

6. What can you say about the length of time and the rate of the reaction?
The less time, the more the reaction rate is lowered, and the more time, the more the reaction rate is higher.

7. What would happen to the rate of reaction if you remove the water and oxygen molecules as soon as they are produced?
It would be faster.

Error Analysis:
All pieces must be returned to the envelope each time interval to correctly simulate what occurs within a cell.

Discussion and Conclusion:
As the time intervals increased, the reaction rate of catalase increased also. In a living cell, more hydrogen peroxide would be broken down by catalase over a longer period of time.

Back

Catalase Lab Sample 1

Enzyme Rate of Reaction for Catalase

Introduction:
Enzymes are an important part of life that regulate chemical reactions with in the body. Enzymes speed up chemical reactions in four different ways, one way is heat, another is increasing the rate of reactants, the third way is decreasing the amount of products and the fourth way is enzymes, which speed up reaction without themselves being used up. Enzymes are also involved in digestion, respiration, reproduction, vision, movement, thought, and also in the productions of other enzymes. Simple cells may have as many as 2000 enzymes with each one catalyzing a different reaction. An enzyme can speed up a reaction making it 10, 000,000,000 times faster. An enzyme is a catalyst. A catalyst is a chemical that reduces the amount of activation interim needed for a reaction. Without enzymes a reaction would take much longer than if it had and enzyme. Enzymes also the control the rate and direction of the reaction.
Without catalysts chemical reactions would take much longer that the average human life expectancy. So that would mean that in 76 years only a couple chemical reactions would take place. Since our bodies have enzymes though hundreds of chemical reactions a day. If our bodies didn’t have catalysts our bodily cells couldn’t function. Some bacteria, however, possess a defense mechanism which can minimize the harm done by the two compounds. These resistant bacteria use two enzymes to catalyze the conversion of hydrogen peroxide back into diatomic oxygen and water. One of these enzymes is catalase and its presence can be detected by a simple test. The catalase test involves adding hydrogen peroxide to a cultures sample or an agar slant.

Hypothesis:
The reaction rate of catalase splitting hydrogen peroxide into water and oxygen will increase over time.

Materials:
The materials used consisted of 100 paper H2O2 molecules, a data table, paper, pencil, calculator, scissors, watch with a second hand, and an enzyme rate of reaction catalase worksheet.

Methods:
Cut out 100 hydrogen peroxide paper molecules. Double check to make sure there are only 100 paper molecules and place them in an envelope. Then one person will keep track of the time while another person acts as a catalase and tears the paper hydrogen peroxide molecules in half. The torn paper molecules should be returned to the envelope each time. Another person times the person acting as the catalase. The time intervals in which the paper molecules are to be ripped are 10 seconds, 20 seconds, 30 seconds, and two different 60second periods of time. The results should be recorded in a data table. The reaction rate for catalase is figured using the formula:
M2 – M1 = Reaction Rate
T2 – T1

Results:

Time in Seconds	Ripped H2O2 Molecules	Rate of Reaction
0-10	5	.5
10-30	13	.4
30-60	31	.6
60-120	61	.5
120-180	91	.5

1. What is an enzyme? What are its functions in living things?
chemicals that reduce the amount of activation energy needed for reactions to occur; they are proteins in cells that control metabolic reactions

2. Name several things that can affect the functioning of an enzyme.
temperature, pH, and the amount of reactant or product

3. Write the chemical equation for the breakdown of hydrogen peroxide by the enzyme catalase.
H2O2 + Catalase –> H2O + O2

4. An enzyme’s efficiency increases with greater substrate concentration, but only up to a point. Why?
once all active sites are filled, the enzyme’s reaction rate won’t continue increasing

5. If you were allowed to continue this lab and rip hydrogen peroxide molecules for 240 and 300 seconds, what would happen to the reaction rate and why would this happen?
there would be more molecules ripped because of the increased amount of time

6. What can you say about the length of time and the reaction rate?
The more time available, the faster the reaction will occur.

7. What would happen to the reaction rate if you removed the water and oxygen molecules as soon as they were produced?
The rate of reaction would go even faster

Error Analysis:
The counting of the time may have been off a couple of seconds.

Discussion and Conclusion:
The data shows that the more time there is, the more hydrogen peroxide molecules will be ripped. The catalase in the lab ripped about 6 molecules every 5 seconds. The same thing occurs in a cell as more hydrogen peroxide is produced, catalase speeds up breaking down this waste into water and oxygen.

Back

Catalase Peroxide Lab

Enzyme Rate of Catalase

Introduction:

Enzymes are molecular substances found in cells. Enzymes act as catalysts and most are proteins. Enzymes bind temporarily to one or more of the reactants of the reaction they catalyze. In doing so, they lower the amount of activation energy needed and thus speed up the reaction.
Not only do enzymes economize energy usage, but also provide a variety of other functions. Cells uses an enzyme (catalase) to rid itself of a poisonous substance (hydrogen peroxide). The rate at which this occurs depends on the amount of catalase that is available. In this lab we are going to measure the time it takes for a disc of filter paper, soaked with different concentrations of enzyme, to make its way to the top of a plastic vial filled with peroxide. Rate of enzyme activity = distance (depth of hydrogen peroxide in mm)/time (in sec).

Catalase catalyzes the decomposition of hydrogen peroxide into water and oxygen. One molecule of catalase can break 40 million molecules of hydrogen peroxide each second.

catalase
2H2O2 —–> 2H2O + O2

Objectives:

Students will prepare various dilute solutions from a 100% enzyme solution.

Students will determine how enzyme concentration affects reaction rate.

Materials:

6 medicine cups for dilutions, *catalase stock solution, clear plastic vial, forceps, 18 filter paper disks, Hydrogen Peroxide (H2O2), paper towel, apron, safety glasses, watch with second hand, marker, metric ruler, calculator

* The enzyme has been prepared for you as follows: 50g of peeled potato was mixed with 50 ml cold distilled water and crushed ice and homogenized in a blender for 30 seconds. This extract was filtered through cheesecloth and cold distilled water was added to a total volume of 100 ml. Extract concentration is arbitrarily set at 100 units/ml. ENZYME SHOULD BE KEPT ON ICE AT ALL TIMES!!

Procedure:

Make a series of dilutions of the enzyme catalase using the following table.

Final Quantity Needed	Concentration of Final Solution	mL of Catalase	mL of Water
10 ml	100%	c10	0
10 ml	80%	8	2
10 ml	60%	6	4
10 ml	40%	4	6
10 ml	20%	2	8
10 ml	0%	0	10

Use a marking pencil and mark the enzyme solutions as follows: 100%, 80%, 60%, 40%, 20%, and 0%.
Fill a clear vial with 20 mL of hydrogen peroxide.
Using your forceps, pick up one filter paper disk and submerge it in the 100% enzyme solution for 5 seconds. Continue to hold the disk with the forceps.
Using your forceps, pick up one filter paper disk and submerge it in the 100% enzyme solution for 5 seconds. Continue to hold the disk with the forceps.
Remove the disk from the solution and blot it dry, for five seconds, using your paper towel.
Drop the disk in the hydrogen peroxide and measure the time it takes for the disk to rise up from the bottom. Begin timing as soon as the disk touches the surface of the hydrogen peroxide.
Use the metric ruler to measure the distance the disk sinks into the hydrogen peroxide. multiply by two to determine the entire distance the disk traveled. Enter the time and distance the disk traveled in the column for Trial 1 in the data table below.

% Catalase	Time in seconds				Distance in millimeters				Reaction Rate mm/s
	Trial 1	Trial 2	Trial 3	Avg.	Trial 1	Trial 2	Trial 3	Avg.
100
80
60
40
20
0

Repeat the above steps for the remainder of the solutions. Remember to use clean filter paper each time you use a different solution. Enter the times and distances for trial 2 and 3 in their appropriate columns.

Analysis & Conclusion:

1. Which concentration of catalase had the fastest reaction time?

2. Which concentration of catalase had the slowest reaction time?

3. What is catalase & why is it important to cells in your body?

4. How did you know that catalase was present in the above compounds?

5. What 2 substances form when catalase breaks down hydrogen peroxide?

6. What type of organic compound is catalase?

7. Produce a line graph of the above data. Use the enzyme concentration as the independent variable and the reaction rate as the dependent variable.

Graph Title:__________________________________________________

Legend:

8. Based on the graph and overall slope of the line, what can you conclude about the effect of enzyme concentration on reaction rate?