8.2.2 Regulation of transcription and translation

• What is the role of transcription factors in gene regulation?

  They regulate transcription of specific target genes
• How do transcription factors bind to DNA?

  They bind to a specific DNA base sequence on a promoter
• Describe the process of transcription regulation by transcription factors.

  They move to the nucleus and bind to DNA

  
• How does oestrogen affect transcription?

  It forms an active transcription factor complex

  
• Why does oestrogen only affect target cells?

  Other cells lack oestrogen receptors
• What is meant by epigenetics?

  Heritable changes in gene function without DNA sequence changes
• What does the term epigenome refer to?

  All chemical modifications of DNA and histones
• What are the key processes involved in epigenetic control of gene expression?

  • Methylation of DNA inhibits transcription
  • Acetylation of histones allows transcription

  
• How does increased methylation of DNA inhibit transcription?

  Methyl groups cause tighter packing of nucleosomes

  
• How does decreased acetylation of histones affect transcription?

  Histones bind DNA more tightly, inhibiting transcription

  
• What is the relevance of epigenetics in disease development?

  Environmental factors can lead to epigenetic changes
• How can epigenetic changes be detected for disease diagnosis?

  Diagnostic tests can identify epigenetic changes
• What is RNA interference (RNAi)?

  Inhibition of translation of mRNA from target genes

  
• How does RNA interference regulate translation?

  siRNA or miRNA binds to target mRNA

  
• What happens to mRNA during RNA interference?

  It is hydrolyzed into fragments and degraded
• What should students be able to do with data on gene expression?

  • Interpret data from investigations
  • Evaluate influences of genetic and environmental factors on phenotype