Cancer+Questions+NLL

Wiki Assignment on Cancer (Answers in Book--Chapter 19)

Define: apoptosis, telomeres, metastasis, tumor, proto-oncogenes, oncogenes, growth factor, tumor suppressor gene, oncology, carcinoma, sarcoma, leukemia, lymphoma

Apoptosis: Programmed cell death involving a cascade of specific cellular events leading to death and destruction of the cell Telomeres: Tip of the end of a chromosome. Metastasis: Spread of cancer from the place of origin throughout the body; caused by the ability of cancer cells to migrate and invade tissues. Tumor: Cells derived from a single mutated cell that has repeatedly undergone cell division; benign tumors remain at the site of the origin, and malignant tumors metastasize. Pro-onceogenes: Normal gene that can become an oncogene through mutation. Oncogenes: Cancer-causing gene. Growth factor: Chemical signal that regulates mitosis and differentiation of cells that have receptors for it; important in such processes as fetal development, tissue maintenance and repair, and hematopoisis; sometimes a contributing factor in cancer. Tumor Suppressor Gene: Gene that codes for a protein that ordinarily suppresses cell division; inactivity can lead to a tumor. Oncology: The study of cancer. Carcinoma: Cancer arising in epithelial tissue. Sarcoma: Cancer that arises in muscles and connective tissues. Leukemia: Cancer of the blood-forming tissues leading to the overproduction of abnormal white blood cells. Lymphoma: Cancer of lymphatic tissue.

1. What do cancer cells look like? A cancer cell does not look like a differentiated epithelial, muscle, nervous, or connective tissue; instead, it looks distinctly abnormal. 2. What is unusual about the nuclei of cancer cells? The nuclei of cancer cells are enlarged and may contain an abnormal number of chromosomes. 3. Why don't cancer cells die? Cells begin to divide too rapidly, thus producing too many new cells, and the old cells don't die off. 4. Describe the three phases of the development of cancer. Initiation: A single cell undergoes a mutation that causes it to begin to divide repeatedly. Promotion: A tumor develops, and the tumor cells continue to divide. As they divide, they undergo mutations. Progression: One cell undergoes a mutation that gives it a selective advantage over the other cells. This process is repeated several times, and, eventually, there is a cell that has the ability to invade surrounding tissues.

5. Mutations in what two types of genes lead to uncontrollable growth? Proto-oncogenes code for proteins that promote the cell cycle and prevent apoptosis. They are often likened to the gas pedal of a car because they cause acceleration of the cell cycle. Tumor-suppressor genes code for proteins that inhibit the cell cycle and promote apoptosis. They are often likened to the brakes of a car because they inhibit acceleration. 6. What is p53? How does it cause cancer? P53 is a protein that turns on genes that stop the cell cycle and activates repair enzymes. If repair is impossible, the P53 protein promotes apoptosis, programmed cell death. Apoptosis is an important way carcinogenesis is prevented. One proto-oncogene codes for a protein that functions to make P53 unavailable. When this proto-oncogene becomes an oncogene, no matter how much P53 is made, none will be available. 7. What is RB? How does it cause cancer? The retinoblastoma protein (RB) that turns on the gene for cyclin D and other genes whose products promote entry into the S phase of the cell cycle. When the tumor-suppressor gene p16 mutates, the RB protein is always functional, and the result is, again, too much active cyclin D in the cell. The cell experiences repeated rounds of DNA synthesis without the occurrence of mitosis. 8. What are the most common cancers cases for males and females? Breast cancer is one of the most common types of cancer. Although predominantly found in women, occasionally it is also found in men. Cancer of the cervix, ovaries, and other reproductive structures also occur in women. In males, prostate cancer is one of the most common cancers. Other cancers of the male reproductive system include cancer of the testis and the penis. Bladder and kidney cancers are associated with the urinary system. Skin cancers include melanoma and basal cell carcinoma. Oral cavity cancer is more frequent in men than women. 9. What are the most common cancer deaths for males and females? Lungs and bronchus, colon and rectum, prostrate, pancreas, leukemia, liver and intrahephatic bile duct, esophagus, non-Hodgkin lymphoma, urinary bladder, kidney and renal pelvis.