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Factors Affecting Gene Expression quiz

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  • What is the central dogma of molecular biology?
    It describes the unidirectional flow of genetic information from DNA to RNA (transcription) and from RNA to protein (translation).
  • What is the role of RNA polymerase in transcription?
    RNA polymerase is the primary enzyme that synthesizes RNA from a DNA template, starting at the promoter region.
  • What is the function of the promoter in a gene?
    The promoter is a DNA sequence where transcription begins and where RNA polymerase binds to initiate RNA synthesis.
  • What is the difference between upstream and downstream DNA sequences relative to a gene?
    Upstream refers to DNA sequences opposite the direction of transcription, while downstream refers to sequences in the same direction as transcription.
  • What modifications occur during eukaryotic RNA processing?
    A 5' cap (modified guanine) is added to the 5' end and a poly-A tail (adenine nucleotides) is added to the 3' end of pre-mRNA.
  • Why are the 5' cap and poly-A tail important for mRNA?
    They facilitate mRNA export from the nucleus, protect it from degradation, and help ribosomes attach for translation.
  • What is RNA splicing and what does it accomplish?
    RNA splicing removes introns (noncoding regions) from pre-mRNA and reconnects exons (coding regions) to produce mature mRNA.
  • What is the function of the spliceosome?
    The spliceosome is a large complex of RNA and protein that removes introns and splices exons together in pre-mRNA.
  • What is alternative RNA splicing?
    Alternative RNA splicing allows a single gene to be spliced in different ways, producing multiple protein products.
  • What is a codon and how is it used in translation?
    A codon is a three-nucleotide sequence in mRNA that specifies a particular amino acid during translation.
  • What is the role of tRNA in translation?
    tRNA carries amino acids to the ribosome and pairs its anticodon with the mRNA codon to ensure correct amino acid placement.
  • What is the difference between charged and discharged tRNA?
    Charged tRNA is attached to an amino acid, while discharged tRNA is not attached to an amino acid.
  • What are post-translational modifications and name four common types?
    Post-translational modifications are covalent changes to proteins after translation; common types include methylation, acetylation, ubiquitination, and phosphorylation.
  • What is a mutation and how can it affect gene expression?
    A mutation is a permanent change in the DNA sequence, which can alter RNA and protein synthesis, affecting protein function.
  • What is the difference between point mutations and frameshift mutations?
    Point mutations change a single nucleotide without altering the reading frame, while frameshift mutations (insertions or deletions) shift the codon reading frame, affecting downstream amino acids.