1. In which phase of mitosis do each of the following occur: a. Centromeres split and chromosomes move toward opposite sides of the cell occur during the anaphase. b. Chromatin coils to form visible chromosomes occur in the prophase. c. The nuclear membrane disappears occur in the prophase. d. Sister chromatids line up in the center of the cell occur in the metaphase. 2. In which phases of mitosis are sister chromatids visible, and attached to each other at the centromere? During the metaphase of mitosis, sister chromatids are visible and attach to each other at the centromere.
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 0 0 1 0 Stomach Tissue Sample 1 16 1 1 0 2 Stomach Tissue Sample 2 18 0 1 0 1 Ovarian Tissue Sample 1 17 0 1 2 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 (in order to get two samples you will need to reset the microscope image).
Tissue Type # Cells in Interphase # Cells in Prophase # Cells in Metaphase # Cells in Anaphase # Cells in Telophase Lung Tissue Sample 1 15 1 3 0 1 Lung Tissue Sample 2 16 0 2 1 1 Stomach Tissue Sample 1 14 2 1 1 2 Stomach Tissue Sample 2 13 2 2 2 1 Ovarian Tissue Sample 1 11 2 2 3 2 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 47. 5% 2. 5% Stomach – normal 42. 5% 7. 5% Ovary – normal 45% 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 38. 75% 11. 25% Stomach – cancerous 33. 75% 16. 25% Ovary – cancerous 28. 75% 21. 25% To calculate the Mitotic Index, the # of cells dividing were the # of cells in the prophase, metaphase, anaphase, and telophase. 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?
I compared the percentages of each tissue from the Mitotic Index in normal and cancerous tissue. The data indicated the cell division rate in normal tissue was less than, or slower than in cancerous tissue. 4. Which type of cancer is the fastest growing? Explain your answer, using your relevant data. The data shows that the ovary cancerous tissue is growing the fastest. Cancerous ovary tissue has the highest Mitotic Index (cell division percentage) and less cells resting on average, which means this type of cancer grows faster than the rest of the other cancerous tissues.
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. Yes, there would be a comparable difference in the cell division rate, due to the fact cancerous tissues divide faster than normal tissue does. b. Could you make a prediction about the average % dividing cells in the cancerous breast tissue? Explain your answer.
I could estimate the average percentage of dividing cells in cancerous breast tissue could range anywhere from 6. 25% to 26. 25%. To find my answer I subtracted the ovary % from the stomach % (21. 25 — 16. 25 = 5), then I subtracted the stomach% from the lung % (16. 25 – 11. 25 = 5). I then added 5 to 21. 25 which would be 26. 25%, the highest percentage on the range, and subtracted 5 from 11. 25% which is 6. 25% as the lowest percentage on the range. 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? Based on the data in the average percentage of dividing cells, the lung cancerous tissue has more cells in the interphase, which means these cells are dividing slower than the other types of cancerous tissues. The average cell dividing percentage in the cancerous tissues of the stomach and ovary is higher than the lung, which means there were less cells of the stomach and ovary during the interphase. 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 younger adults might not be unaware, or even ignorant about the possible risk of developing skin cancer. Younger adults might think “it won’t happen to me, or I’m too young to get skin cancer”.
One factor that is most common to developing skin cancer would be from excessive and unprotected exposure to the sun. It might be more common for younger adults to go tanning, and the UV light exposure is another contributing factor. Most importantly, I think young adults might not be aware of the increase of people with skin cancer around that age group. There could also be a lack of education about the signs of skin cancer, such as changes in a mole’s color, size and shape. Lack of protection and lack of education about skin cancer would probably seem to be the most contributing factors young adults face.