2022_HCI_Molecular Basis of Cancer

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Core Idea 2 / Molecular Basis of Cancer 1 Molecular Basis of Cancer The development of cancer is a multi -step process that comprises gene mutations caused by environmental factors, biological agents or hereditary predispositions. These mutations might cause cells to bypass cell cycle checkpoints. Normally, two groups of genes are involved in regulating cell division: tumour suppressor genes and proto-oncogenes. Mutations in either or both of these groups of genes may lead to the development of cancer. Cancer has a much higher incidence in Singapore compared to other diseas es and accounts for as much as 30 per cent of the deaths in this country. The recorded incidence of cancer is on the rise and this could be due to the accumulation of mutations from one generation to the next, although other reasons have also been proposed: increased exposure to carcinogens and increased detection rates as a result of effective cancer screening programmes. As such, an understanding of how cancer develops is important as this would set the platform for discussion of developing anti-cancer drugs. Learning Outcomes Candidates should be able to: 2(p) identify the causative factors, including genetic, chemical carcinogens, ionising radiation and loss of immunity, which may increase the chances of cancerous growth 2(q) explain how the loss of function mutation of tumour suppressor genes, including p53, and gain in function mutation of proto-oncogenes, including ras, results in uncontrolled cell division 2(r) describe the development of cancer as a multi -step process that includes accumulation of mutations, angiogenesis and metastasis Use the knowledge gained in this section in new situations or to solve related problems Learning Experiences 2.5.1 Uncontrolled Cell Division This SLS lesson explains how dysregulation of the cell cycle can result in uncontrolled cell division. In addition, it explains how mutation of two groups of genes (tumour suppressor gene and proto-oncogene) can result in uncontrolled cell division. 2.5.2 Cancer This SLS lesson describes the factors that increase the chance of cancer development, and explains that cancer development is a multi-step process.

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Core Idea 2 / Molecular Basis of Cancer 2 2.5.3 Useful information about Cancer About 30 percent of deaths in Singapore are related to cancer (the principal cause of death in 2011). Through studies on families with high incidence of cancer, certain cancer genes such as BRCA have been elucidated. The following websites provide useful information about cancer: The following websites provide useful information about cancer: i. General cancer information – Singapore cancer statistics ii. Principal causes of death

HWA CHONG INSTITUTION / 2022-2023 H2 BIOLOGY / Core Idea 2 / Molecu