1. In which phase of mitosis do each of the following occur: a. Centromeres split and chromosomes move toward opposite sides of the cell- Anaphase b. Chromatin coils to form visible chromosomes – Prophase c. The nuclear membrane disappears- Prophase d. Sister chromatids line up in the center of the cell- Metaphase 2. In which phases of mitosis are sister chromatids visible, and attached to each other at the centromere? Metaphase Table 1: Record your data for the number of cells in each stage of the cell cycle observed in normal tissues. Tissue Type # Cells in Interphase # Cells in Prophase # Cells in Metaphase # Cells in Anaphase # Cells in Telophase Lung Tissue Sample 1 19 1 0 0 0.
Lung Tissue Sample 2 19 1 0 0 0 Stomach Tissue Sample 1 18 0 1 0 1 Stomach Tissue Sample 2 18 0 1 0 1 Ovarian Tissue Sample 1 19 0 0 1 0 Ovarian Tissue Sample 2 19 0 0 1 0 Table 2: Record your data for the number of cells in each stage of the cell cycle observed in cancerous tissues. Tissue Type # Cells in Interphase # Cells in Prophase # Cells in Metaphase # Cells in Anaphase # Cells in Telophase Lung Tissue Sample 1 16 0 2 1 1 Lung Tissue Sample 2 16 0 2 1 1 Stomach Tissue Sample 1.
14 2 1 1 2 Stomach Tissue Sample 2 14 2 1 1 2 Ovarian Tissue Sample 1 12 2 1 2 3 Ovarian Tissue Sample 2 12 2 1 2 3 Table 3: Use the data in Table 1 to calculate the Mitotic Index (average % cells dividing) for each normal tissue type. Tissue Type Avg. % cells at rest Mitotic Index Lung – normal 95% 5% Stomach – normal 90% 10% Ovary – normal 95% 5% Table 4: Use the data in Table 2 to calculate the average % cells dividing and average % cells at rest in each cancerous tissue type. Tissue Type Avg. % cells at rest Mitotic Index Lung – cancerous 80% 20% Stomach – cancerous 70% 30%.
Ovary – cancerous 60% 40% Questions: 3. What does your data indicate about the rate of cell division in cancerous tissue compared to the rate of cell division in normal tissue? What data did you use to answer this question? The data indicates that the rate of cell division in cancerous tissue is faster in all of the tissues that it is in normal tissues. In order to answer this question you can look at both the average percent of cells at rest and the mitotic index. The lower the percent of cells at rest and the higher the mitotic index means that there is more cell division.
4. Which type of cancer is the fastest growing? Explain your answer, using your relevant data. According to the data that was obtained, the type of cancer that is fastest growing would be in the ovary cells. The reason for this is because the cancerous cells in the ovaries have a mitotic index of 40%, while the other two areas have a mitotic index of 20% and 30%. 5. With what you have observed in this lab, if you were to compare tissue sample from normal breast tissue and cancerous breast tissue: a. Would you expect to see a difference in the rate of cell division in the cancerous breast tissue compared to the normal breast tissue? Explain your answer.
Based upon the information that I have learned from this experiment, one can predict that there will be a difference in the rate of cell division in normal breast tissue and cancerous breast tissue. One can come to this conclusion because when we compared the cells from 3 different areas there was also a difference in the rate of cell division between the cancerous and normal tissues. With that being said, you would also expect the cancerous cells to have a higher rate of cell division.
b. Could you make a prediction about the average % dividing cells in the cancerous breast tissue? Explain your answer. Using the data from the experiment you can predict that the average percent of dividing cells in the cancerous breast tissue would be between 20%-40%. You could come to this conclusion because that is what the data we observed in the experiment showed us. 6. Consider the % dividing cells in normal lung, normal stomach, and normal ovarian tissue. Why do you think there are more cells dividing in the stomach and ovary tissue than in the lung tissue?
You would expect for the normal lung cells to not have to divide as often because those cells are not exposed to many things through out the day. The normal stomach cells on the other hand would be expected to divide more because there is a lot of acidity in the stomach and therefore those cells are exposed to a lot of things on a daily basis. As for the ovaries you would expect that there would be a little more cell division because that is where new life is formed and all of the things that come along with that which means that there should be more division going on.
7. This lab explores three common cancers. An additional form of cancer – Skin Cancer – used to be seen only in older individuals but is now seen in younger individuals, many in their early 20s. Skin cancer results from accumulated mutations to the DNA of skin cells, caused primarily by sun exposure. What factors do you think may be contributing to the increase in skin cancer among young adults? I think that there are multiple factors that are major contributing points to the fact that there is an increase in skin cancer among young adults.
One of these factors is that teens are now so concerned with getting a great tan and being “darker” than their friends when they come back to school in the fall. This means that not only are the individuals exposed to the full effect of the sun earlier in life but it also means that they are exposed to a lot more of it than people used to be at their age. I think another factor is that because people are so worried about getting their tan that there are a large majority of people that use tanning booths now which leads to a more concentrated effect of sun exposure.