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Gene Regulation in General Biology

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Termini in questo insieme (25)

  • What does 'gene expression' refer to?
    The entire process from transcription to translation of a functional protein, not just transcription.
  • Why do genetically identical somatic cells have different shapes and functions?
    Because of differential gene expression regulated by transcription factors.
  • What is an operon in bacteria?
    A cluster of genes under control of a single promoter and operator, regulated together.
  • What is the role of the operator in an operon?
    It is the DNA segment where repressor proteins bind to turn transcription off; when unbound, transcription is on.
  • What advantage does an operon provide by controlling multiple genes?
    It allows coordinated regulation of genes with related functions, saving energy and resources.
  • Name key components regulating transcription in prokaryotes.
    Operon, promoter, operator, multiple genes, repressor protein, activator protein, corepressor, RNA polymerase.
  • What molecules regulate the lac operon?
    Lactose, allolactose (inducer), glucose, cAMP, CAP (activator), repressor protein.
  • How does the trp operon regulate gene expression?
    Tryptophan acts as a corepressor that binds the repressor to turn transcription off when tryptophan is abundant.
  • How is transcription initiation regulated in eukaryotes?
    By transcription factors, RNA polymerase, promoter, and the transcription initiation complex.
  • What is the transcription initiation complex?
    A protein assembly including transcription factors and RNA polymerase needed to start transcription.
  • What role do activator proteins play in eukaryotic transcription?
    They bind to enhancers and help assemble the transcription initiation complex to start transcription.
  • What is epigenetic inheritance?
    Heritable changes in gene expression without changes in DNA sequence, often via histone acetylation or DNA methylation.
  • How does histone acetylation affect gene expression?
    It loosens chromatin structure, making DNA more accessible and increasing gene expression.
  • How does DNA methylation affect gene expression?
    It tightens chromatin and typically represses gene expression.
  • What happens to gene expression when no transcription factors bind the promoter?
    Gene expression is turned off because RNA polymerase cannot initiate transcription.
  • What is alternative splicing?
    A process where different exons are joined to produce multiple protein variants from one gene.
  • How does alternative splicing increase protein diversity?
    By allowing one gene to code for multiple proteins through different mRNA variants.
  • What determines the lifespan of an mRNA molecule?
    Features like the untranslated regions (UTRs) and the poly A tail influence mRNA stability.
  • What portion of the human genome codes for proteins?
    Only a small fraction of the genome codes for proteins.
  • What proportion of the genome is transcribed but not translated?
    A large portion is transcribed into noncoding RNAs that regulate gene expression.
  • How do microRNAs (miRNAs) regulate gene expression?
    They bind to mRNA to block translation or promote degradation, reducing protein production.
  • What is cell differentiation?
    The process by which cells become specialized in structure and function.
  • How do cytoplasmic determinants influence cell differentiation?
    Maternal RNAs and proteins unevenly distributed in the egg cytoplasm affect gene expression in daughter cells.
  • What is induction in embryonic development?
    Signaling molecules from one group of cells influence gene expression in neighboring cells to guide differentiation.
  • What causes cancer in terms of gene regulation?
    Genetic changes that disrupt normal cell cycle control lead to unregulated cell division.