THE EUKARYOTIC CELL CYCLE AND CANCER: AN OVERVIEW ABOUT THIS WORKSHEET This worksheet complements the Click and Learn “The Eukaryotic Cell Cycle and Cancer” and is intended as a straightforward introduction to the cell cycle and how it relates to cancer. For a more comprehensive student worksheet, please see the in-depth version. PROCEDURE Read through the Click and Learn at (http://www.hhmi.org/biointeractive/eukaryotic-cell-cycle-and-cancer) to learn about the cell cycle. Answer the questions below. Click on the “Background” tab on the right side. Read the information and watch the videos. Click on the purple section labeled “Cell Cycle Phases” as well as the words “Mitosis” and “Interphase” to read an overview of the cell cycle. You can also click on the various phases. Cells go through periods of growth and division. Cell division occurs during ___. The rest of the cell cycle is called interphase, during which _________________. Fill in the details about what happens during the three phases of interphase labeled in the diagram. In general, what is the purpose of a checkpoint in the cell cycle? Click on the “Background” tab on the right side. Read the information and watch the videos. 1. Why is cell division important for both unicellular and multicellular organisms? 2. Why does cell division remain important to an adult organism even after it is fully developed? 3. Cells divide, differentiate, or die. What is differentiation? 4. What is apoptosis? What is its purpose? 5. What are cell cycle regulators? 6. What happens if cell cycle regulators don’t function properly
The Correct Answer and Explanation is:
1. Why is cell division important for both unicellular and multicellular organisms?
Cell division is essential for both unicellular and multicellular organisms because it is the process through which organisms grow, reproduce, and repair damaged tissue. In unicellular organisms, cell division leads to reproduction, creating new individuals through asexual reproduction. In multicellular organisms, it allows for growth and development, where cells divide to form tissues and organs. Additionally, it helps repair damaged cells and tissues, ensuring the organism’s health and functionality.
2. Why does cell division remain important to an adult organism even after it is fully developed?
Even after an organism is fully developed, cell division remains crucial. It is responsible for the replacement of cells that are constantly dying (such as skin cells and red blood cells). Additionally, cell division plays a role in tissue repair when damage occurs (e.g., healing a wound) and in maintaining the balance of cell numbers within tissues. Without ongoing cell division, an organism would struggle to repair itself and maintain homeostasis.
3. Cells divide, differentiate, or die. What is differentiation?
Differentiation is the process by which a cell becomes specialized to perform a specific function within the organism. During development, stem cells (unspecialized cells) can differentiate into various types of cells, such as muscle cells, nerve cells, or skin cells. Differentiation involves changes in gene expression, where certain genes are activated or deactivated, allowing the cell to take on its specialized structure and function.
4. What is apoptosis? What is its purpose?
Apoptosis, also known as programmed cell death, is a process by which cells undergo an orderly and controlled death. It is essential for maintaining the health of an organism. Apoptosis removes cells that are damaged, infected, or no longer needed, preventing them from becoming harmful or dysfunctional. This process helps prevent cancer, as it eliminates cells that could potentially become cancerous due to mutations or other abnormalities.
5. What are cell cycle regulators?
Cell cycle regulators are proteins that control the progression of the cell cycle. They include cyclins and cyclin-dependent kinases (CDKs), which help ensure that the cell moves through the various stages of the cycle in an orderly manner. These regulators respond to signals that promote or halt cell division, ensuring that the cell only divides when it is appropriate (e.g., when the DNA is intact and ready for division).
6. What happens if cell cycle regulators don’t function properly?
If cell cycle regulators do not function properly, the cell cycle can become disrupted, leading to uncontrolled cell division. This is a hallmark of cancer. For example, when regulators like tumor suppressor genes (e.g., p53) are mutated or absent, damaged cells may continue to divide, leading to the accumulation of genetic mutations. Conversely, if proto-oncogenes (genes that promote cell division) are overactive, it can also lead to uncontrolled cell growth. The failure of these regulatory mechanisms can result in tumor formation and cancer.
Conclusion:
The cell cycle is tightly regulated to maintain healthy cellular function. Disruptions in this regulation can lead to serious conditions like cancer, where cells divide uncontrollably. Cell division is essential throughout an organism’s life for growth, repair, and maintaining normal function. Apoptosis and differentiation play key roles in ensuring that only healthy, functional cells persist.
