3.2 Genetic Regulation

• What does genetic regulation cover?

  Transcription to protein formation
• Why is regulation of gene expression important for living organisms?

  It allows response to environmental changes
• How does differential regulation of gene expression benefit multicellular organisms?

  It allows specialized functions in different cell types
• Do cardiac myocytes and renal tubular epithelial cells have the same genetic code?

  Yes, they contain the same genetic code
• What is the ultimate measure of gene expression?

  Production of gene products (proteins)
• At what points can regulation of gene expression occur?

  Transcription, RNA processing, and translation
• What initiates the synthesis of cellular proteins?

  Transcription of DNA into RNA
• What controls the transcription of DNA?

  Regulatory elements in the promoter
• What is the TATA box?

  A sequence of seven bases (TATAAAA)
• What is the role of the TATA-binding protein?

  It binds to the TATA box in the promoter
• What is the transcription factor IID complex?

  A group of proteins that assist transcription
• What does transcription factor IIB do?

  Binds to DNA and RNA polymerase 2
• Where is the basal promoter found?

  In all protein-coding genes
• What must bind to the basal promoter for transcription to begin?

  RNA polymerase
• What is the function of the upstream promoter?

  Contains binding sites for transcription factors
• How do transcription factor binding sites in the upstream promoter vary?

  They differ from gene to gene
• What is the process of gene expression regulation?

  • Transcription of DNA into RNA
  • RNA processing
  • Translation of RNA into proteins
• What are the roles of the basal and upstream promoters?

  Basal promoter:

  • Contains TATA box
  • Required for RNA polymerase binding

  
  

  Upstream promoter:

  • Contains binding sites for transcription factors
  • Influences transcription regulation
• What influences the transcription of genes in eukaryotes?

  Enhancers and transcription factors
• What are enhancers in the context of gene transcription?

  Regions of DNA that bind transcription factors
• How can enhancers be located in relation to the genes they act on?

  They can be distant or on different chromosomes
• Where can enhancers be located in relation to the regulated gene?

  Upstream or downstream of the gene
• How does DNA coiling affect enhancer proximity to target genes?

  Enhancers may be close when DNA is coiled
• How many gene enhancer sequences are estimated to be in the human genome?

  110,000 gene enhancer sequences
• Why is it important to separate active genes from repressed genes?

  To prevent transcriptional interference
• What are chromosomal insulators and their function?

  They provide a barrier to isolate specific genes
• How do insulators vary in their characteristics?

  They vary in DNA sequence and binding proteins
• How can insulator activity be modulated?

  Through DNA methylation
• What role does the mother's allele play in IGF-2 gene expression?

  It has an insulator allowing repressor binding
• How does the paternal DNA sequence affect IGF-2 gene expression?

  It is methylated, preventing repressor binding
• What happens to the IGF-2 gene from the paternal copy?

  It is expressed due to lack of repressor
• What has been rapidly discovered in the past 2 decades regarding transcription control?

  Variations in the basic mechanism for control
• How is a promoter frequently controlled?

  By transcription factors located elsewhere in the genome
• What role does a regulatory gene play in transcription control?

  It causes the formation of a regulatory protein
• What can a regulatory protein act as in transcription control?

  Either an activator or a repressor
• How many different promoters can be controlled by the same regulatory protein?

  Many different promoters
• How can the same regulatory protein function for different promoters?

  As an activator for one and a repressor for another
• Where can some proteins be controlled besides the starting point of transcription?

  Farther along the DNA strand
• What is one way control can occur during RNA processing?

  Before RNA is released into the cytoplasm
• At what level can control occur during RNA translation?

  During protein formation in the cytoplasm