Mutation+of+Cancer+Cells

Genetic Mutation:
Genetic mutation is caused by the failure of one or more genes, which usually occurs when something in the cell cycle goes wrong [1] [2] [3]. A cell mutation is particularly concerning because the mutation is passed on when the mutated cell divides, producing more mutated cells [2] [5]. The mechanism for cell mutation is shown in Figure 1 below. An example of cell mutation caused by genes is cancer [1] [2] [3] [5]. When certain genes malfunction, cancer cells may develop [1] [2] [3] [5]. Such genes include oncogenes, tumour suppressor genes or DNA repair genes [1] [2] [4] [5]. Proto-oncogenes are those which encourage cell division [2] [5]. The purpose of this gene is to replace dead or damaged cells [1] [5]. If this gene malfunctions, it becomes an oncogene and causes the cell to begin to multiply uncontrollably [4] [5]. Tumour suppressor genes are the opposite to proto-oncogenes, but when they fail they have the same undesirable effect [1] [4] [5]. These genes cause a cell to stop dividing, but a malfunction disables it from telling the cell to stop dividing [1] [4] [5]. In both cases, the cell has to produce telomerase to compensate for its extra division, and hence becomes immortalised and forms a cancerous cell [3]. DNA repair genes, as the name suggests, repair damaged DNA strands which make up other genes [1] [5]. If these cells fail, any other mutations of the cell that occur will not be able to be repaired, and so the cell would carry its mutation and pass it on each time it divides [1] [5].

Figure 1: Mechanism of Cell Mutation (Picture obtained from Stanford Medicine 2011) By Ashlea Norton //Last edited 11/11/2011//

References:
 [1] Cancer Research UK 2011, 3/11/2011-last update//, How Cancer Starts// [Homepage of Cancer Research UK], [Online]. Available: @http://cancerhelp.cancerresearchuk.org/about-cancer/what-is-cancer/cells/how-cancer-starts [2011, 6/11/2011].

[2] Collins, K., Jacks, T. & Pavletich, N.P. 1997, "The Cell Cycle and Cancer", //Proceedings of the National Academy of Sciences of the United States of America,// vol. 94, no. 7, pp. 2776-2778.

 [3] Dahse, R., Fiedler, W. & Ernst, G. 1997, "Telomeres and Telomerase: Biological and Clinical Importance", //Clinical Chemistry,// vol. 43, no. 5, pp. 708-714.

 [4] Osborne, C., Wilson, P. & Tripathy, D. 2004, "Oncogenes and Tumour Suppressor Genes in Breast Cancer", //The Oncologist,// vol. 9, no. 4, pp. 361-377.

 [5] Stanford Medicine 2011, 24/10/2011-last update//, How Genes Cause Cancer// [Homepage of Stanford School of Medicine], [Online]. Available:@http://cancer.stanford.edu/information/geneticsAndCancer/genesCause.html [2011, 6/11/2011].