Transcript of Biology P2
Cell Division, Gene Expression, and Causes of Cancer Cell Division is regulated by genes Proto-oncogenes cell growth cell division ability of cells to adhere one another Mutation oncogene -uncontrolled cell proliferation over expression of proteins at inappropriate times during cell cycle Tumor Development abnormal proliferation of cells that causes swelling of a part of the body Benign Tumor Malignant Tumor generally pose no threat to life unless they are allowed to grow until it compress vital organs Most benign tumors can be remove by surgery uncontrolled dividing cells invade and destroy healthy tissues in the body Causes Cancer tumor-suppressor genes prevent cell division from occurring too often cells have three types of tumor-suppressing genes, which all must be damage before cancer can occur In cancer, if tumor-suppressor genes are damage: activity of tumor-suppressing decreases rate of cell division increases Gene Expression Oncogenes and mutated tumor-suppressor genes causes cancer cells to behave differently Normal cells attach to other cells, a membrane, or fibers between cells to divide normal cells will stop dividing after about 40 cell divisions or sooner Cancer cells continue to divide indefinitely even when densely packed Ignore the normal cellular message to stop dividing Divide even not attach to other cells Metastasis Spread of cancer cells beyond their original site When occur, cancer cells can invade healthy tissues and begin forming new tumors Causes of Cancer Carcinogen substance that can induce or promote cancer Examples: Chemicals in tobacco smoke Chemicals such as nickel Ionizing radiation such as X rays The UV radiation from the sun, sun lamps, and tanning booths People with certain jobs such as painters, construction workers, and in the chemical industry have increased risk of cancer due to expose of chemicals Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. Sources "What Is Gene Expression?" What Is Gene Expression? Ed. April Cashin-Garbutt. News Medical, n.d. Web. 12 Mar. 2013. <http://www.news-medical.net/health/What-is-Gene-Expression.aspx>. Modern Biology by Holt, Rinehart, andFull transcript
Postlethwait A proto-oncogene is a normal gene that can become an oncogene due to mutations or increased expression. Proto-oncogenes code for proteins that help to regulate cell growth and differentiation. Proto-oncogenes are often involved in signal transduction and execution of mitogenic signals, usually through their protein products. Upon ''activation'', a proto-oncogene (or its product) becomes a tumor-inducing agent, an oncogene. Activation The proto-oncogene can become an oncogene by a relatively small modification of its original function. There are three basic activation types: An increase in enzyme activity A loss of regulation An increase in protein concentration An oncogene is a gene that, when mutated or expressed at high levels, helps turn a normal cell into a tumor cell. Since the 1970s, dozens of oncogenes have been identified in human cancer. Most oncogenes require an additional step, such as mutations in another gene, or environmental factors, such as viral infection, to cause cancer. "Tumor Development." Infoplease. Infoplease, n.d. Web. 13 Mar. 2013. <http://www.infoplease.com/encyclopedia/science/cancer-medicine-tumor-development.html>.