Transcription Factors

• What do eukaryotes use to control gene expression?

  Transcription factors
• What are transcription factors?

  Proteins that bind to DNA regions
• What percentage of human genes code for transcription factors?

  ~10%
• How do transcription factors affect gene expression?

  They have varying effects on expression
• What is the current state of research on transcription factors?

  It is a relatively young area of research
• How do transcription factors help organisms?

  They allow responses to environmental changes
• How do some hormones achieve their effects?

  Via transcription factors
• Where do some transcription factors bind on a gene?

  To the promoter region of a gene
• What is the effect of transcription factor binding on transcription?

  It can allow or prevent transcription
• What does the presence of a transcription factor do to transcription rates?

  It can increase or decrease transcription rates
• What role does oestrogen play in mammals?

  It controls the oestrus cycle and sperm production
• What type of molecule is oestrogen?

  A lipid-soluble molecule
• How does oestrogen enter cells?

  By diffusing through the plasma membrane

  
• What does oestrogen bind to in the nucleus?

  To an oestrogen receptor

  
• What happens when oestrogen binds to its receptor?

  It causes a change in the receptor's shape

  
• What does the receptor do after binding with oestrogen?

  It binds to the promoter region of target genes

  
• What is the result of the receptor binding to the promoter region?

  RNA polymerase can bind and transcription begins

  
• What role does gibberellin play in plants?

  It controls seed germination
• How does gibberellin influence amylase gene transcription?

  By stimulating the synthesis of amylase

  
• What happens when gibberellin is applied to a germinating seed?

  Increased mRNA for amylase is present
• What is necessary for amylase synthesis?

  The breakdown of DELLA protein by gibberellin

  
• What components are involved in gibberellin's action?

  DELLA protein and transcription factor PIF

  
• What does DELLA protein do in relation to transcription factors?

  It prevents transcription factor binding to the promoter

  
• What initiates the breakdown of DELLA protein?

  Gibberellin binding to its receptor

  
• What happens after DELLA protein is broken down?

  The transcription factor binds to the amylase gene promoter

  
• What is the final outcome of gibberellin's action on the amylase gene?

  Transcription of the amylase gene begins
• Why is RNA analysis important for gene expression?

  It shows which genes are being expressed
• What can be analyzed to determine gene expression in cells?

  RNA produced by transcription
• What is a key observation about cells with identical DNA?

  They express different genes
• Are specific transcription factors required to be recalled for the exam?

  No, they are not required