The p53 gene is a tumor-suppressor gene while p634  gene is an oncogene. Mutation in either one can result in the transformation of a normal cell into a cancer cell. Explain the difference between the functions of the two proteins and how their mutation can lead to cancer development.

Another model, the random model, proposes that any cell in a malignant tumor has the potential to form a new tumor. Does the cancer stem cell hypothesis contradict this idea?

Benign tumors: a. are noncancerous growths that do not spread to other tissues b. do not contain mutations c. are malignant and clonal in origin d. metastasize to other tissues e. none of these

A gene that codes for a positive cell cycle regulator is called a(n) _______. a. kinase inhibitor b. tumor suppressor gene c. proto-oncogene d. oncogene

Two genes associated with breast cancer, BRCA1 and BRCA2, were discovered in 1994 and 1995, respectively, and shortly thereafter, were patented by Myriad Genetics, a company based in Utah. Under the patents, testing for mutations in these genes could only be performed by Myriad, at costs from 300 to 3,000. Myriad also patented the process of analyzing the results of such tests, preventing anyone who obtains the sequence of their BRCA genes by other means (which itself would probably be patent infringement) from interpreting the information. The idea that genes can be patented has been a contentious issue from the beginning. Patents are not granted for products of nature, meaning that genes inside the body are not patentable, but biotech companies successfully argued that by removing a gene from the human body, purifying it, and then obtaining its DNA sequence, they created something not found in nature, and which is therefore a patentable invention. The U.S. Patent Office found the argument persuasive, but opponents argue that genes are parts of our bodies and can be identified but not invented. Biotech companies argue that without the protection offered by patents, they would have no incentive for research and development of diagnostic tests. In Europe, patents for BRCA1 and BRCA2 were revoked in 2004 because they did not meet the standards for a patent. After more than a decade of legal disputes, the patents were partially restored in 2008 on a very restricted basis. In the United States, a lawsuit, focused on the patents for the BRCA genes, was filed in May 2009. The suit challenges the basic idea that genes are patentable. In November 2009, the judge ruled that the lawsuit can proceed, and the case is moving forward. In March 2010, a federal court invalidated Myriad Genetics patent on these genes. In August 2011, the U.S. Court of Appeals reversed the lower courts decision and ruled that gene sequences isolated from cells are not a product of nature and are therefore patentable. The case went to the U.S. Supreme Court, which ordered the appeals court to reconsider the case. The Federal Appeals Court did not change its decision, and the case once again, went to the U.S. Supreme Court. A unanimous decision in June 2013 invalidated Myriads patents on the basis that isolating a gene from nature does not make it patentable. This is a landmark decision on gene patenting with widespread ramifications for the biotechnoloogy industry. Will this decision reduce the incentives for companies to invest in new diagnostic tests that would be used by cancer victims or those with serious genetic disorders?

________ are changes to the nucleotides in a segment of DNA that codes for a protein. a. Proto-oncogenes b. Tumor suppressor genes c. Gene mutations d. Negative regulators

You are in charge of a new gene therapy clinic. Two cases have been referred to you for review and possible therapy. Case 1. A mutation in the promoter of a proto-oncogene causes the gene to make too much of its normal product, a receptor protein that promotes cell division. The uncontrolled cell division has caused cancer. Case 2. A mutation in an exon of a tumor-suppressor gene makes this gene nonfunctional. The product of this gene normally suppresses cell division. The mutant gene cannot suppress cell division, and this has led to cancer. What treatment options can you suggest for each case?

One unexpected result of the sequencing of the human genome was the finding that mutations in a single gene can be responsible for multiple distinct disorders. For example, mutations in the RET gene can cause two different types of multiple endocrine neoplasias, familial medullary thyroid carcinoma, and Hirschsprung disease. How do you think mutations in a single gene can have such diverse effects?

Which of the following structures could be found within the nucleolus?

List the regulatory mechanisms that might be lost in a cell producing faulty p53.