lecture 25 - genetics of cancer

• What is the purpose of RNA interference in the cell?

  It is stimulated in the presence of double-stranded RNA
• Which of the following is an example of post-transcriptional control of gene expression?

  The removal of introns and alternative splicing of exons
• What are the guiding questions for the class on the genetics of cancer?

  • How can we use our knowledge of genetics to understand cancer?
  • What are the different types of cancer?
  • What causes cancer?
  • Is cancer heritable?
• If a young woman develops breast cancer due to a mutation in a single breast cell, what is likely true about her children?

  Some of the woman’s children may inherit the mutation depending on which chromosome they inherit
• What percentage of cancer-causing mutations are typically inherited from one’s parents?

  10%
• What are the phases of the cell cycle?

  • Interphase (~90% of the cell cycle)
  • G1 Phase: Metabolic activity and growth
  • S Phase: DNA synthesis
  • G2 Phase: Preparation for cell division
  • Mitotic Phase: Mitosis and Cytokinesis

  
• What occurs during the G1 phase of the cell cycle?

  Metabolic activity and growth

  
• What is the role of proto-oncogenes in cell division?

  They detect and respond to signals that stimulate a cell to divide
• What happens when mutations occur in the Ras proto-oncogene?

  They can lead to a hyperactive Ras protein

  
• What is the function of tumor suppressor genes?

  They detect errors in DNA replication and respond to correct them or undergo programmed cell death
• What is an example of a protein that plays a role in stopping or slowing down cell division?

  p53

  
• What are the common causes of DNA damage related to cancer?

  • Mutations in p53 prevent suppression of the cell cycle
  • Environmental factors (e.g., chemicals, radiation)
  • Errors during DNA replication

  
• What is the multistep model of cancer development?

  • More than one mutation is needed for full-fledged cancer
  • At least one active oncogene
  • Mutation of several tumor-suppressor genes

  
• What are the key ideas about the inheritance of cancer-causing mutations?

  1. Mitosis occurs in somatic cells, producing identical offspring cells.
  2. Meiosis occurs in germline cells, producing genetically unique gametes.
  3. New mutations can occur in somatic or germline cells.
  4. Only mutations in germline cells and gametes can be inherited.
• What type of cells undergo mitosis?

  Somatic cells
• What type of cells undergo meiosis?

  Germline cells
• What happens to mutations in somatic cells?

  They will not be passed on to progeny
• What happens to mutations in germline cells?

  They will be passed on to progeny
• What is aflatoxin and its relation to cancer?

  • Aflatoxin is produced by Aspergillus fungus.
  • It can interact with DNA and cause mutations.
  • High exposure to aflatoxin is linked to liver cancer.

  
• How does aflatoxin exposure relate to liver cancer incidence?

  Higher aflatoxin exposure is associated with higher liver cancer incidence

  
• What happens to DNA replication when there is an aflatoxin adduct attached?

  DNA polymerase mispairs an A with the aflatoxin adduct on a G

  
• What is a mutation?

  A change in the DNA sequence

  
• What should society do about plastics in relation to cancer?

  • Investigate the potential carcinogenic effects of plastics.
  • Promote research on alternatives to harmful plastics.
  • Educate the public on safe plastic use.