Objective:
The objective of this lab is to better understand the processes of mitosis and meiosis by observing and conducting various experiments.
The objective of this lab is to better understand the processes of mitosis and meiosis by observing and conducting various experiments.
Investigation One: Models
Part One: Mitosis
Hypothesis:
If a model of mitosis is built out of Oreo cookies then we will be able to better visualize and understand the process of cell division
Procedures:
Step 1: Remove the top cookie from six cookies.
If a model of mitosis is built out of Oreo cookies then we will be able to better visualize and understand the process of cell division
Procedures:
Step 1: Remove the top cookie from six cookies.
- Carefully, twist the top piece of the cookie from the bottom in order to have the bottom piece covered in the cream.
- For the fifth cookie, break the bottom piece in half.
- Choose two colors that will represent the chromosomes. (We chose yellow and pink sprinkles).
- Each cookie will represent a phase in the process of mitosis.
- Underneath each cookie, label the phase with a marker.
Justification:
My model demonstrates each phase that occurs in mitosis. My data table above explains in more detail what happens in each one of these phases. The table also provides a key in order to show what each aspect in my model represents.
Analysis Questions:
Analysis:
One step where a mistake could occur would be during telophase. During this phase, the chromosomes begin to lengthen as they unwind in order to form new cells. If the spindle apparatus is still present then this can not happen. So, if the spindle apparatus does not disappear, then the chromosomes can not form new cells, essentially not allowing cell division to happen.
My model has some limitations compared to observing this process in the real world because the Oreo cookies do not show the exact details of what occurs in each phase. For example, my model does not show the spindle fibers. Spindle fibers are important aspects during mitosis because they help perform different tasks in each phase in order for the cell to divide. So, without details such as this one, the oreo cookie demonstration is not as accurate as a model used in the real world.
Conclusion:
In the model, my hypothesis was supported because we were able to see each step on how the cell divides. We could see this due to the oreo cookies and sprinkles demonstrating how the chromosomes align, migrate towards the poles, and eventually split and break into two. A possible error that occurred during this experiment was that the model did not give enough detail. The model did not include the spindle, poles, and spindle fibers therefore not making it as accurate as possible. If the experiment was to be done again, then the model would include the components stated above in order to provide a more clear picture of cell division. Overall, we were able to see how cell division works in a fun and creative way!
My model demonstrates each phase that occurs in mitosis. My data table above explains in more detail what happens in each one of these phases. The table also provides a key in order to show what each aspect in my model represents.
Analysis Questions:
- Identify 1 step in your model where a mistake could occur. Describe the consequences of that mistake on the cell and on the organism.
- Describe the limitations of your model versus observing this in the real world.
Analysis:
One step where a mistake could occur would be during telophase. During this phase, the chromosomes begin to lengthen as they unwind in order to form new cells. If the spindle apparatus is still present then this can not happen. So, if the spindle apparatus does not disappear, then the chromosomes can not form new cells, essentially not allowing cell division to happen.
My model has some limitations compared to observing this process in the real world because the Oreo cookies do not show the exact details of what occurs in each phase. For example, my model does not show the spindle fibers. Spindle fibers are important aspects during mitosis because they help perform different tasks in each phase in order for the cell to divide. So, without details such as this one, the oreo cookie demonstration is not as accurate as a model used in the real world.
Conclusion:
In the model, my hypothesis was supported because we were able to see each step on how the cell divides. We could see this due to the oreo cookies and sprinkles demonstrating how the chromosomes align, migrate towards the poles, and eventually split and break into two. A possible error that occurred during this experiment was that the model did not give enough detail. The model did not include the spindle, poles, and spindle fibers therefore not making it as accurate as possible. If the experiment was to be done again, then the model would include the components stated above in order to provide a more clear picture of cell division. Overall, we were able to see how cell division works in a fun and creative way!
Investigation One: Models
Part Two: Meiosis
Hypothesis:
If a model of meiosis is built out of Oreo cookies then we will be able to better visualize and understand the process of cell division.
Procedures:
Step 1: Remove the top cookie from fourteen cookies.
If a model of meiosis is built out of Oreo cookies then we will be able to better visualize and understand the process of cell division.
Procedures:
Step 1: Remove the top cookie from fourteen cookies.
- Carefully, twist the top piece of the cookie from the bottom in order to have the bottom piece covered in the cream.
- For the cookie representing cytokinesis, break the bottom piece in half.
- Choose two colors that will represent the chromosomes. (We chose yellow and pink sprinkles).
- Choose one color to represent the spindle fibers. (We chose red sprinkles).
- Each cookie will represent one phase from the process of meiosis.
- Underneath each cookie, label the phase with a marker.
Justification:
My model demonstrates each phase that occurs in meiosis. My data table above explains in more detail what happens in each one of these phases. The table also provides a key in order to show what each aspect in my model represents.
Analysis Questions:
Analysis:
One step in my model where a mistake could occur would in anaphase. During this phase, the chromosomes may not completely separate which would result in an abnormal amount of chromosomes. If the cell holds more than the normal amount of chromosomes, then the organism will be negatively affected. For example, in humans, if one is born with extra chromosomes then the individual will be affected with syndromes such as Down Syndrome and Edwards Syndrome.
Mitosis and meiosis have both similarities and differences. The main difference between the two is that during prophase in mitosis, the two chromatids do not exchange segments while during prophase in meiosis, the two chromatids do exchange segments through what we call “crossing over.” Also, in mitosis the cell only divides once while in meiosis the cell divides twice. However, mitosis and meiosis are similar because they both share the same processes in order for cell division to occur. The only difference is that meiosis include more phases than mitosis.
Conclusion:
In the model, my hypothesis was supported because we were able to see each step on how the cell divides. We could see this because the oreo cookies and sprinkles demonstrated each phase starting with prophase I and ending with cytokinesis to result in four haploid cells. A possible error that occurred during this experiment was that the model could be misinterpreted. The model included the spindle and poles so, if one did not know the process of meiosis they would become confused with the other various sprinkles displayed in the model. If the experiment was to be done again, then the model would describe the components stated above in order to provide a more clear picture of cell division. Overall, we were able to see how cell division works in a fun and creative way!
My model demonstrates each phase that occurs in meiosis. My data table above explains in more detail what happens in each one of these phases. The table also provides a key in order to show what each aspect in my model represents.
Analysis Questions:
- Identify 1 step in your model where a mistake could occur. Describe the consequences of that mistake on the organism's possible progeny.
- Compare and Contrast the process of mitosis and meiosis.
Analysis:
One step in my model where a mistake could occur would in anaphase. During this phase, the chromosomes may not completely separate which would result in an abnormal amount of chromosomes. If the cell holds more than the normal amount of chromosomes, then the organism will be negatively affected. For example, in humans, if one is born with extra chromosomes then the individual will be affected with syndromes such as Down Syndrome and Edwards Syndrome.
Mitosis and meiosis have both similarities and differences. The main difference between the two is that during prophase in mitosis, the two chromatids do not exchange segments while during prophase in meiosis, the two chromatids do exchange segments through what we call “crossing over.” Also, in mitosis the cell only divides once while in meiosis the cell divides twice. However, mitosis and meiosis are similar because they both share the same processes in order for cell division to occur. The only difference is that meiosis include more phases than mitosis.
Conclusion:
In the model, my hypothesis was supported because we were able to see each step on how the cell divides. We could see this because the oreo cookies and sprinkles demonstrated each phase starting with prophase I and ending with cytokinesis to result in four haploid cells. A possible error that occurred during this experiment was that the model could be misinterpreted. The model included the spindle and poles so, if one did not know the process of meiosis they would become confused with the other various sprinkles displayed in the model. If the experiment was to be done again, then the model would describe the components stated above in order to provide a more clear picture of cell division. Overall, we were able to see how cell division works in a fun and creative way!
Investigation Two: Studying the Effects of Environment on Mitosis
Part Three: Time Spent in the Phases of Mitosis
Hypothesis:
If we observe a cell as it goes through the cell cycle, then we can see that most of its time is spent in interphase.
Procedures:
Step 1: Use the online lab activity that Mrs. Blake provided if the in-class experiment does not work.
If we observe a cell as it goes through the cell cycle, then we can see that most of its time is spent in interphase.
Procedures:
Step 1: Use the online lab activity that Mrs. Blake provided if the in-class experiment does not work.
- http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/01.html
- Click on each cell and place in the phase where it belongs.
- Classify each cell until all the cells have been categorized.
Analysis:
To calculate the amount of time spent in each phase of the cell cycle from the percentage of cells in that stage. On the average, it take 1,440 minutes (24 hours) for onion root tip cells to complete the cell cycle.
% of cells in stage x 1440 minutes = _____ minutes of cell cycle spent in stage.
The cells in interphase spent 806 minutes in that stage. The cells in prophase spent 403 minutes in that stage. The cells in metaphase spent 115 minutes in that stage. The cells in anaphase spent 86 minutes in that stage. The cells in telophase and cytokinesis spent 43 minutes in that stage.
Conclusion:
This experiment was done using the online lab activity that was provided by Mrs. Blake because the in-class experiment did not work. In this experiment, my hypothesis was proved correct. The experiment supported my claim that a cell spends most of its time in interphase because as I collected data, I was able to determine that a cell spends 803 minutes in interphase, more than every other phase the cell has to go through. Some possible sources of error were classifying the cell into the wrong phase. However, the online activity would inform you when you misplaced a cell so, no errors could be made when calculating the time each cell spent in a phase. If the experiment had to be repeated, no changes would be made to the online lab experiment because it provided me accurate results. In all, I was able to learn that a cell spends most of their time in interphase as well as prophase while only a small percentage of their time is spent in metaphase, anaphase, and telophase.
To calculate the amount of time spent in each phase of the cell cycle from the percentage of cells in that stage. On the average, it take 1,440 minutes (24 hours) for onion root tip cells to complete the cell cycle.
% of cells in stage x 1440 minutes = _____ minutes of cell cycle spent in stage.
The cells in interphase spent 806 minutes in that stage. The cells in prophase spent 403 minutes in that stage. The cells in metaphase spent 115 minutes in that stage. The cells in anaphase spent 86 minutes in that stage. The cells in telophase and cytokinesis spent 43 minutes in that stage.
Conclusion:
This experiment was done using the online lab activity that was provided by Mrs. Blake because the in-class experiment did not work. In this experiment, my hypothesis was proved correct. The experiment supported my claim that a cell spends most of its time in interphase because as I collected data, I was able to determine that a cell spends 803 minutes in interphase, more than every other phase the cell has to go through. Some possible sources of error were classifying the cell into the wrong phase. However, the online activity would inform you when you misplaced a cell so, no errors could be made when calculating the time each cell spent in a phase. If the experiment had to be repeated, no changes would be made to the online lab experiment because it provided me accurate results. In all, I was able to learn that a cell spends most of their time in interphase as well as prophase while only a small percentage of their time is spent in metaphase, anaphase, and telophase.
Investigation Four: Loss of Cell Cycle Control in Cancer
Part Four: Karyotypes
Based on your knowledge about human chromosomal disorders and nondisjunction due to loss of control during the cell cycle, identify the name of the syndromes and karyotypes of the following patients.
Conclusion:
In this investigation, rather than presenting a hypothesis to prove, the investigation wanted to center around how extra or missing chromosomes would affect the human body. We were given the normal karyotypes for male and female and asked to examine the karyotypes of three patients. In each case, there was an extra chromosome. These extra chromosomes showed how these individuals resulted with syndromes such as Down Syndrome, Edwards Syndrome, and Patau Syndrome. Possible sources of error in this investigation would be accidentally counting the wrong amount of chromosomes which would result in less than normal chromosomes or chromosomes being added onto the wrong strand. This would result in not finding the correct syndromes that the investigation wants us to research. If this experiment was to be done again, accurately and carefully counting the chromosomes would be a change made in order to correctly identify the syndromes. In all, chromosome numbers are important because without the correct number, your body will be negatively affected.
In this investigation, rather than presenting a hypothesis to prove, the investigation wanted to center around how extra or missing chromosomes would affect the human body. We were given the normal karyotypes for male and female and asked to examine the karyotypes of three patients. In each case, there was an extra chromosome. These extra chromosomes showed how these individuals resulted with syndromes such as Down Syndrome, Edwards Syndrome, and Patau Syndrome. Possible sources of error in this investigation would be accidentally counting the wrong amount of chromosomes which would result in less than normal chromosomes or chromosomes being added onto the wrong strand. This would result in not finding the correct syndromes that the investigation wants us to research. If this experiment was to be done again, accurately and carefully counting the chromosomes would be a change made in order to correctly identify the syndromes. In all, chromosome numbers are important because without the correct number, your body will be negatively affected.
Investigation 5: Meiosis and Crossing Over in Sordaria
Part 5: Meiosis and Crossing Over in Sordaria
Study the pictures of Sordia in the picture below by counting at least 50 asci and scoring them as either parental or recombinant.
- If the ascospores are arranged 4 dark/4 light, count the ascus as “No crossing over.”
- If the arrangement of ascospores is in any other combination, count it as “Crossing over.”
- Record your results in the data table provided.
Conclusion:
This investigation did not require a hypothesis to be proven, instead it asked to determine which strands of asci showed crossing over and which did not. From the data I collected, I am able to conclude that there is a larger number of asci crossing over compared to the number of asci that did not cross over. A possible source of error during this investigation could have been inaccurately determining an asci as crossing over when it is the opposite. This misinterpretation would have altered the data and caused inaccurate results. If this experiment were to be done again, then I would make sure that each asci was correctly looked at and determined if it appeared to be crossing over or not.
This investigation did not require a hypothesis to be proven, instead it asked to determine which strands of asci showed crossing over and which did not. From the data I collected, I am able to conclude that there is a larger number of asci crossing over compared to the number of asci that did not cross over. A possible source of error during this investigation could have been inaccurately determining an asci as crossing over when it is the opposite. This misinterpretation would have altered the data and caused inaccurate results. If this experiment were to be done again, then I would make sure that each asci was correctly looked at and determined if it appeared to be crossing over or not.