Regulation of transcription/translation (BIOL5)

Question 1

Features of transcription factors

Answer 1

• Control transcription of target genes
  
  • Move from cytoplasm to nucleus
    
    • Bind to spec DNA sites near start of target genes - genes control expression of
  • Control expression by controlling rate of transcription
• Activators and repressors

Question 2

Activators (transcription factor)

Answer 2

Inc. rate of transcription

Help polymerase bind to start of gene and activate transcription

Question 3

Repressors (transcription factor)

Answer 3

Dec. rate of transcription

Bind to start of target gene, preventing polymerase fr binding, stopping transcription

Question 4

Oestrogen as a transcription factor

Answer 4

• Levels affect rate of transcription of target cells
• Bind to transcription factor called oestrogen receptor - form oestrogen-oestrogen receptor complex
  
  • Complex moves from cytoplasm –> nucleus to bind w/ spec DNA sites near start of target gene
    
    • Can act as activator or repressor - depends on cell and target gene

Question 5

Role of siRNA in gene expression

Answer 5

• Small interfering RNA
• Interfere w/ gene expression
• Short, double-stranded RNA
• Bases complementary to spec sections of target gene and mRNA formed
• Can interfere w/ translation by RNA interference
  
  • In cytoplasm, siRNA and associated protein bind to target mRNA
  • Proteins cut up mRNA into sections - can’t be translated
    
    • Prevents expression as protein not made during translation