Cancer is the name given to the disease in which changes in gene expression cause an uncontrollable division of abnormal cells in any given part of the body. Cell growth and division are regulated by specific genes, and these genes include those for growth factors, along with their receptors, and the intracellular molecules of signaling pathways. Cancer can occur whenever a mutation alters any of these genes. These mutations can be random and spontaneous, however they can also be caused by environmental factors such as chemicals, radiation, and X-rays. Oncogenes are mutated genes that play a role in transforming a normal cell into a cancerous tumor cell. Proto-oncogenes are normal genes that become oncogenes when mutations cause them to be
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The role of tumor suppressor genes is to inhibit cell division and limit the growth of tumors. A type of tumor suppressor gene, known as the p53 gene, is known for its role in repairing damaged DNA. It will often activate other genes that help to slow down the cell cycle and buy some time to repair damaged DNA. If the damage caused to DNA is deemed irreparable, the p53 gene can activate genes responsible for apoptosis, which is programmed cell suicide. If tumor suppressor genes like the p53 gene are unable to serve their function and prevent mutations from occurring and being passed on, cancer is a potential outcome (Campbell, pg. 384). Therefore, choice A is correct.
Choice B states that tumor suppressor genes are most likely to result in cancer through gain of function mutations. A gain of function mutation will enhance the activity of a protein. In this case, proteins will be able to inhibit the cell cycle and control the growth of cells that might result in cancer. Damaged DNA will be corrected and the p53 gene will not have to go through drastic measures to prevent mutations from being passed along (Campbell, pg. 384). This answer choice is the opposite of choice A, which was already proven to be the correct choice. Therefore, choice B is
The role of tumor suppressor genes is to inhibit cell division and limit the growth of tumors. A type of tumor suppressor gene, known as the p53 gene, is known for its role in repairing damaged DNA. It will often activate other genes that help to slow down the cell cycle and buy some time to repair damaged DNA. If the damage caused to DNA is deemed irreparable, the p53 gene can activate genes responsible for apoptosis, which is programmed cell suicide. If tumor suppressor genes like the p53 gene are unable to serve their function and prevent mutations from occurring and being passed on, cancer is a potential outcome (Campbell, pg. 384). Therefore, choice A is correct.
Choice B states that tumor suppressor genes are most likely to result in cancer through gain of function mutations. A gain of function mutation will enhance the activity of a protein. In this case, proteins will be able to inhibit the cell cycle and control the growth of cells that might result in cancer. Damaged DNA will be corrected and the p53 gene will not have to go through drastic measures to prevent mutations from being passed along (Campbell, pg. 384). This answer choice is the opposite of choice A, which was already proven to be the correct choice. Therefore, choice B is