Molecular Biology of Cancer • What are the environmental influences that are cancer-causing? • What is the difference between an oncogene and a proto-oncogene? • What genetic changes convert proto-oncogenes to oncogenes? • Reference page 272 (Fig 15.12) to understand alterations of chromosome structure: relate this to the statement “Malignant cells are frequently found to contain chromosomes that have broken and rejoined incorrectly, translocating fragments.”
Molecular Biology of Cancer. What are the environmental influences that are cancer-causing? What is the difference between an oncogene and a proto-oncogene? What genetic changes convert proto-oncogenes to oncogenes? - PowerPoint PPT Presentation
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Molecular Biology of Cancer
• What are the environmental influences that are cancer-causing?
• What is the difference between an oncogene and a proto-oncogene?
• What genetic changes convert proto-oncogenes to oncogenes?
• Reference page 272 (Fig 15.12) to understand alterations of chromosome structure: relate this to the statement “Malignant cells are frequently found to contain chromosomes that have broken and rejoined incorrectly, translocating fragments.”
Molecular Biology of Cancer (responses)
• Chemical carcinogens, physical mutagens (X-rays) or certain viruses
• Proto-oncogene: normal cellular genes-code for proteins that stimulate normal cell growth and division
• Oncogene: cancer-causing gene• “An oncogene arises from a genetic change
that leads to an increase in either the amount of proto-oncogene’s protein product or intrinsic activity of each protein molecule”
Cancer Understood
• Explain how the location of the proto-oncogene being located adjacent to an active promoter leads to an oncogene.
• What is amplication?• Explain how a point mutation can change the
gene’s protein product and therefore lead to an oncogene.
Alterations of Chromosome Structure
3 Main Categories of Oncogene Conversion
• Movement of DNA within the genome – Translocation or transposition– **new controls / new promoter
• Amplication of proto-oncogene– Increases number of copies of the gene in the cell
• Point mutation in proto-oncogene– More active or resistance to degradation than
• Functions:– Repair damaged DNA– Control adhesion of cells to each other– Cell signaling—inhibit cell cycles
• If altered, the suppression is decreased and therefore cancer can be the outcome
Ras (30%) versus p53 (50%)
• In general, what is the difference between a oncogene and a tumor suppressor gene? Relate them to cancer.
• Signal transduction Pathways: A set of chemical reactions in a cell that occurs when a molecule, such as a hormone, attaches to a receptor on cell membrane. The pathway is actually a cascade of biochemical reactions inside the cell that eventually reach the target molecule or reaction. Thus, the pathway is a method by which molecules inside the cell can be altered by molecules on the outside.
Ras
• Normal ras job:• What does ras need to do its job?• How is the oncogene of Ras hyperactive?
p53
• What are the main functions of a normal functioning p53? (hint: at least 3 ways)
Cancer and Age
• Why does the incidence of cancer increase with age?
• How does this help explain the predispositions to cancer that run in some families?
• Explain “dominant oncogenes and recessive tumor-suppressors”.
• How do active telomerases relate to cancer?
Viruses
• How do they contribute to cancer development?
• Define retrovirus (use back of book)
BRCA1 and BRCA2
• What does BRCA stand for?• What type of cancers are these genes related