Table 2. Data collected while observing the prepared slides of whitefish blastula in class. Number of cells in phase was calculated by counting 20 adjacent whitefish blastula cells and the cell which are in interphase or actively dividing stage was determined.
Table 3. Data collected while observing the prepared slide of onion root tip in class. Class was divided into pairs and they each drew the diagrams of the process of mitosis of each stage. All students in the class recorded the data which was needed to calculate the field of view, drawing of fit and calculated the magnification. Percentage of cells division and the standard of deviation were later calculated by the individuals.
Table 4. Data collected while observing the prepared slide of whitefish blastula in class. Class was divided into pairs and they each drew the diagrams of the process of mitosis of each stage. All students in the class recorded the data which was needed to calculate the field of view, drawing of fit and calculated the magnification. Percentage of cells division and the standard of deviation were later calculated by the individuals.
Qualitative Description:
The onion root tip cells were green and rectangular and fixed shape. There were nuclei in the cells which were in a darker shade of green, cell wall, cell membrane and cytoplasm which was in light shade of green. The immature onion root tip cell had nuclei at the bottom of the cell and the mature onion root tip cell had nuclei on the top of the cell. When the cells were in the middle of mitosis, some chromosomes, spindle microtubules and cell plate could be seen through the microscope. Overall, there were more cells which were in the process of interphase than the cells which were actively dividing. Other organelles in the onion root tip cell were too small for the magnification of the current microscope used in class.
The whitefish blastula cells were light purple and it didn’t have a fixed shape like the onion root tip cells. There were nuclei in cells which were in a darker shade of purple, cell membrane and cytoplasm which was in light shade of purple. When the cells were in the middle of mitosis, some chromosomes, spindle microtubules and cleavage furrow could be seen through the microscope. Other organelles in the whitefish blastula cell were too small for the current magnification of the microscope in class.
Data Processing:
Overview:
The raw data which was collected while observing the Onion Root Tip cells and Whitefish Bastula cells for the frequency of division were represented in a table format. Since tables are very useful when presenting two dimensions of information or viewing the data in an easier way, the raw data was presented in a table format. The raw data was also represented in a pie graph to have clear view of how frequent each stage takes place during the process of mitosis.
Sample Calculation:
% of Cells Dividing = Number of cells dividing X 100
Total Number of cells counted
Onion Root Tip Cell:
Prophase (%) = 33 X 100
50
= 3300
50
= 66%
Mataphase (%) = 6 X 100
50
= 600
50
= 12%
Anaphase (%) = 8 X 100
50
= 800
50
= 16%
Telophase (%) = 3 X 100
50
= 300
50
= 6%
Whitefish Bastula
Prophase (%) = 36 X 100
50
= 3600
50
= 72%
Mataphase (%) = 5 X 100
50
= 500
50
= 10%
Anaphase (%) = 7 X 100
50
= 700
50
= 14%
Telophase (%) = 2 X 100
50
= 200
50
= 4%
Presentation:
Figure 1. The pie graph represents the percentage of cells dividing in onion root tip cells.
Figure 2. The pie graph represents the percentage of cells dividing in whitefish blastula cells.
CONCLUSION & EVALUATION:
Conclusion:
Through this experiment, there were some physical similarities and differences between whitefish blastula cells and onion root tip cells. They were similar in the structures of mitosis and structure of the cell. Both cells had same process in stages in mitosis and they both contained similar organelles like nucleus, microtubules and chromosomes. However, they were different in the process of mitosis and some in structures. Whitefish blastula cells, which are animal cells and onion root tip cells, which are plant cells differed in mitosis. The difference was evident at the stage of telophase when cells were dividing into two cells. In plant cell, which is onion root tip cell, the cell created a cell plate in the middle of two cells. On the other hand, in animal cell, which is whitefish blastula cell, the cell created a cleavage furrow in the middle of two cells. Whitefish blastula cells did not contain cell wall but only contained cell membrane because they were animal cells but onion root tip cells contained both cell wall and cell membrane because they were plant cells. Also plant cell had stages of immature and mature cells while animal plant cells only had one stage which was interphase.
The percentage of frequency of cell division was calculated by multiplying number of cells from specific stage by 100 and then dividing those by the total number of cell counted. From table 3 and 4, it is shown that prophase was the most occurring stage in mitosis. From the table 3, 66% of stages in mitosis were prophase in plant cell and from table 4, 72% of stages in mitosis were prophase in animal cell. From table 1 and 2, the data shows that interphase was the most occurring stages during mitosis. Relating the data from all tables, it could be concluded that interphase is the most occurring stage in mitosis since all stages must go though interphase before proceeding to other stages of mitosis. Spindles were visible in both animal and plant cells. However, spindles in plant cells were less visible than those in animal cell. In plant cells, spindles were in light shade of green and in animal cells, spindles were dark shade of purple but the size of animal cells prevented us from taking closer view of them. This might have resulted due to lack of power from the compound light microscope.
Limitations of Experimental Design:.
In overall, the experiment was successful because we were able to find the frequency of division and the differences between animal and plant cells in the stages of mitosis. However, it might have not worked well because of the errors we could’ve made. Some of the things which worked well were finding all phases in mitosis and calculating the frequency of division. While observing the cells from each slide, it was quite hard to distinguish stages of mitosis since there weren’t that many cells which were in distinct stages. Most cells were in the middle of stages so it was hard to determine them to be in specific stage. However, my partner and I were able to find all the distinct stages of mitosis. Also we were able to count the cells and find the frequency of division.
Some of the random error could have made due to the distraction from other people in class. For example, my partner and I could have miscounted number of cells across the field of view and that might have caused some errors in actual length, actual width and actual magnification of both types of the cells. Some of the systematic error we could have made was due to the prepared slides of each type of cells. We could have miscounted the cells in each phase of mitosis. Some of the things which did not work well were time management, distinguishing stages of mitosis and focusing cells into view. There were enough time given for the class to work on the lab but my partner and I couldn’t manage the class time very well so we couldn’t finish the lab in class. Therefore, we had to work during lunch time in order to finish with the observation of plant and animal cells. Focusing the cells into view consumed lots of time at the beginning of the lab. When my partner and I were first observing the onion root tip cell, we couldn’t find the cells and it took us quite a long time to put them into view. After we put cells in to view, it was hard for us to distinguish each stages of mitosis. Some cells were in the middle of both stages so it was hard to find distinct stages of mitosis to draw the diagram.
There were some limitations in this lab. All cells in slide were frozen so we weren’t able to observe how cells process mitosis and how long mitosis took precisely. There was only one type of microscope so this could have limited us from seeing different or clearer view of cells. In addition, some of the high-power objective lenses did not work for some microscopes. Thus, we had to use medium-power to view the cells and this prevented us from having clear view of cells. Also, we were limited in number of slides because we could only see one type of each plant and animal cell which were onion root tip cells and whitefish blastula cells.
Suggestion for Improvement:
Some of the suggestion for improvement for this lab is to have more slides and compare the group of the same type of cell. For this lab, we had to compare between onion root tip cells and whitefish blastula cells. However, there are more plant cells or animal cells other than onion root tip and whitefish blastula. For next lab, we could get more samples for both type of cells and compare samples within the type of the cells. For plant cells, we can compare different parts of vegetables and fruits. For animal cells, we could get samples of fish, amphibians, reptiles or mammals and compare each of them to find the similarities and differences in stages of mitosis or the frequency of division.
ANALYSIS QUESTION:
Part 1: Observing Dividing Cells
- Meristematic area and the mature cells are different in position of the nucleus, structure of the cells and the size of the cells. In meristematic cells of the root, they are more square and smaller than the mature cell and the nucleus is at the bottom of the cell. On the other hand, mature cells of the root are more rectangular, larger than the meristematic cell and the nucleus is at the top of the cell.
- The onion root tip cells and whitefish blastula cells were used for viewing cell division because they are organisms which process mitosis and they each represent two different types of cells.
- The cells which were viewed under the microscope did not continue to divide because they were frozen during the process of mitosis so that we could have clear view of what happens during the process of mitosis.
Part 2: Determining the Frequency of Cell Division
-
% Dividing = Number of cells dividing X 100
Total number of cells counted
Plant Cell (onion root tip cell)
(Interphase) % dividing = 18 X 100
20
= 1800
20
= 90%
(Cells in Division) % dividing = 2 X 100
20
= 200
20
= 10%
Animal Cell (whitefish blastula cell)
(Interphase) % dividing = 16 X 100
20
= 1600
20
= 80%
(Cells in Division) % dividing = 4 X 100
20
= 400
20
= 20%
- They are similar in a way that interphase is the most occurring stages. They are different because interphase occurs more in the onion root tip cells compared to the whitefish blastula cells.
Part 3: Creating a Cell-Division Clock
-
% of Cells Dividing = Number of cells dividing X 100
Total Number of cells counted
Onion Root Tip Cell:
Prophase (%) = 33 X 100
50
= 3300
50
= 66%
Mataphase (%) = 6 X 100
50
= 600
50
= 12%
Anaphase (%) = 8 X 100
50
= 800
50
= 16%
Telophase (%) = 3 X 100
50
= 300
50
= 6%
Whitefish Bastula
Prophase (%) = 36 X 100
50
= 3600
50
= 72%
Mataphase (%) = 5 X 100
50
= 500
50
= 10%
Anaphase (%) = 7 X 100
50
= 700
50
= 14%
Telophase (%) = 2 X 100
50
= 200
50
= 4%
- If it takes 16 h to complete one cycle of mitosis for whitefish and 12 h for onions, determine the time spent in each phase. Include this information in your circle graphs.
Onion Root Tip:
Time in minute= 12h X 60min
= 720 minutes
The time each phase takes = 720 minutes X % of each phase
Prophase (min) = 720 min X 0.66
= 475.2 min
Metaphase (min) = 720 min X 0.12
= 86.4 min
Anaphase (min) = 720 min X 0.16
= 115.2 min
Telophase (min) = 720 min X 0.06
= 43.2 min
Whitefish Blastula:
Time in minute= 16h X 60min
= 960 minutes
The time each phase takes = 960 minutes X % of each phase
Prophase (min) = 960 min X 0.72
= 691.2 min
Metaphase (min) = 960 min X 0.1
= 96 min
Anaphase (min) = 960 min X 0.14
= 134.4 min
Telophase (min) = 960 min X 0.04
= 38.4 min
Synthesis
-
The number of animal cells in each phase of mitosis was recorded in Table 1. If the time taken to complete one cycle of mitosis was 15h, create a cell-division clock to represent the data.
Prophase (%) = 15 X 100
50
= 1500
50
= 30%
Mataphase (%) = 20 X 100
50
= 2000
50
= 40%
Anaphase (%) = 10 X 100
50
= 1000
50
= 20%
Telophase (%) = 5 X 100
50
= 500
50
= 10%
Time in minute = 15h X 60 minutes
= 900 minutes
The time each phase takes = 900 minutes X % of each phase
Prophase (min) = 900 min X 0.3
= 270 min
Metaphase (min) = 900 min X 0.4
= 360 min
Anaphase (min) = 900 min X 0.2
= 180 min
Telophase (min) = 900 min X 0.1
= 90 min