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Cell Cycle and Cancer
Deep Analysis
Deep Analysis
Cell Cycle and Cancer
Deep Analysis
Use the questions below to go deeper into the scientific concepts and applications of each Investigation. Note that questions highlighted in orange text are also featured in Phase 3.1 (Conclusions) of the Student Guide PDF.
Investigation 1
1. Extensive unprotected exposure to the Sun can damage cells in the epidermis, causing cells to die and slough off. The body loses thousands of these cells each day. How do you think the skin is maintained? Cells that are damaged and die are replaced through cell division.
2. Would the function of the lung be affected if the alveoli were surrounded by walls made of several layers of cells rather than a single layer of cells? How? If the alveoli were surrounded by cells, several layers think the the oxygen from the air and carbon dioxide from the blood would have to travel further, making it more difficult to breathe properly. This would definitely alter the lung’s function.
3. To transform inactive to active breast tissue requires a large increase in the number of cells within the lobes and ducts. Where do you think these extra cells come from? The extra cells needed to make the larger lobes and ducts are produced through cell division of the existing cells in these tissues.
Investigation 2
1. What phase of the cell cycle was the model of the inactive breast cell most of the time? The inactive breast tissue cell was most likely in the G1 phase most of the time. However, students may suggest that it was in G2. It is not likely that a cell would be in the S or M phase for one year.
2. Why do the embryonic and inactive breast tissue cells divide at different rates? The cells serve different functions. The cells have different amounts of regulatory proteins (pins in the model).
3. What do you think would happen if an inactive tissue cell (such as inactive breast tissue or lung tissue) lost all of the proteins controlling its cell cycle? The cell will divide uncontrollably. A tumor (cancer) may result.
Investigation 3
1. What is the relationship between the control of the cell cycle and cancer? Normally the cell cycle is regulated so that cells only progress through the cycle and divide when necessary. In cancer, the regulation of the cell cycle is lost and the cell divides constantly. The constant cell proliferation leads to a tumor and cancer.
Comprehension Check
1. How does the organization of cells within an organ relate to an organ’s function? The cells are organized into tissues. Each tissue provides a function that contributes to the function of the organ. In the skin, the epidermal tissue is composed of closely packed cells that serve as a protective barrier between the external environment and the body. The dermis serves to contain connective tissue and blood vessels needed to maintain the integrity of the epidermis. The subcutaneous layer contains fat cells important in keeping us warm. The lung has alveoli that are lined with a single layer of alveolar (epithelial) cells. This thin layer allows the lung to function by permitting easy oxygen and carbon dioxide exchange to occur between inhaled air and the blood. Finally, in the breast tissue, you could see the organization of the glandular tissue cells to form the lobes and ducts needed to store and transport milk.
2. How do cells in an organism replenish themselves after normal wear and tear on the tissue? Students may answer by discussing that cells replenish themselves by a process of cell division, which is regulated by the cell cycle.
3. How do tissues replenish the cells contained within them? Tissues replenish cells through cell division. Cell division has four phases: G1, S, G2, and M. During the S phase, DNA is replicated, and during the M phase, mitosis and cytokinesis (cell division) occur. Mitosis can be broken down into four stages: prophase, metaphase, anaphase, and telophase.
4. What controls the process of cell division? Different proteins regulate the cell cycle. The time it takes for a cell to complete the cycle depends on which regulatory proteins are present in that cell at any given time.
5. What is the relationship between the control of the cell cycle and cancer? Normally the cell cycle is regulated so that cells only progress through the cycle and divide when necessary. In cancer, the regulation of the cell cycle is lost and the cell divides constantly. The constant cell proliferation leads to a tumor and cancer.