Gene expression and cancer

• Describe alterations to tumour suppressor genes that may cause cancer

  1. Mutation that causes it to lose function
  2. Increases methylation
  3. Decreases acetylation of surrounding histones

  Leads to:

  • Uncontrolled cell division occurs because only proton-oncogenes are functioning
• Describe alterations to proto-oncogenes that may cause cancer

  1. Mutation that causes it to gain function
  2. Decreased methylation
  3. Increased acetylation of surrounding histones

  Leads to:

  • Uncontrolled cell division because the rate of mitosis is too fast (oncogene)
• Describe how a tumour is formed from proto-oncogenes

  They code for proteins that initiate and speed up cell division

  A mutation may cause the protein to increase its function so it becomes an oncogene

  The cell divides at a rapid and uncontrolled rate so a tumour forms
• Describe how a tumour is formed from tumour suppressor genes

  They code for proteins that inhibit and slow down cell division

  A mutation may cause the protein to decrease in function

  The cell divides at a rapid and uncontrolled rate so a tumour forms
• Compare benign and malignant tumours

  • Benign contains non cancerous cells where as malignant contain cancerous cells that divide rapidly and uncontrollably
  • In benign, cells remain localised but in malignant, cells break off to another tissue where secondary tumours can form, called metastasis
  • Benign contain differentiated cells but malignant contain some undifferentiated cells
  • Both can cause blockages and impair normal function