Genetics Ch. 13 Transcription

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  1. Transcription
    Synthesis of a single stranded RNA copy of a segment of DNA.
  2. mRNA
    Encodes the amino acid sequesnce of a polypeptide.
  3. rRNA
    Makes up the ribosomes.
  4. Ribosomes
    The structures which translate mRNA and construct polypeptides.
  5. tRNA
    Bring amino acids to the ribosomes during translation.
  6. snRNA
    • Small nuclear RNA.
    • Forms complexes with proteins for RNA processing in eukaryotes.
  7. Gene regulatory elements.
    Sequences involved in regulating transcription.
  8. RNA polymerase
    • Catalyzes transcription.
    • In prokaryotes unwinds DNA.
  9. Template strand
    Unwound portion of DNA in the 3' to 5' direction.
  10. RNA precursors
    • ATP
    • GTP
    • CTP
    • UTP
    • Collectively called NTPs (nucleoside triphosphates)
  11. Promoter
    A sequence updstream from the start of transcription that interacts with RNA polymerase to begin transcription. Ensures that initiation of every RNA begins at the same site.
  12. Terminator
    Specifies where transcription will stop.
  13. Holoenzyme
    • A form of RNA polymerase which binds to the promoter.
    • The core enzyme form of RNA polymerase.
    • Has four polypeptides (2 alpha, 1 beta, 1 beta prime, bound to the sigma factor)
  14. Terminator
    Specifies where transcription will stop.
  15. Closed promoter complex
    The full promoter bound to the closed double helix.
  16. Open promoter complex
    The promoter untwist the DNA double helix.
  17. Sigma factor
    Part of the promoter that dissociates soon after transcription begins.
  18. Terminator sequences
    Signals the end of transcription.
  19. Rho dependent terminators
    • Termination of transcription depends on the Rho protein.
    • Has RNA-binding and ATPase domains.
    • Rho binds to RNA as it exits the RNA polymerase.ATP is hydrolysed causing the RNA to separate from the RNA poymerase and DNA template.
  20. Rho independent terminators
    • The core RNA polymerase itself carries out termination.
    • Consist of an inverted repeat sequence. This sequence causes a hairpin loop to be formed.
  21. RNA polymerase I
    • Located in the nucleus.
    • Catalyses 28s, 18s, and 5.8s RNA's found in ribosomes.
  22. RNA polymerase II
    • Found only in the nucleoplasm.
    • Synthesizes mRNA ans some snRNA.
  23. RNA polymerase III
    • Found in nucleoplasm.
    • Synthesizes tRNA, 5sRNA, and snRNA.
  24. Core promoter
    • Assists in starting transcriptionat the correct site.
    • TATA box; sequence of nucletides that specifies where transcrition machinery assembles.
  25. Promotoer proximal elements
    • Upstream from the TATA box.
    • CAAT box.
  26. Enhancers
    • Required for maximal transcription of genes.
    • Modulate transcription.
  27. Leader sequence
    Untranslated region.
  28. Coding sequence
    Specifies the amino acid sequence during translation.
  29. trailer sequence
    untranslated region following the coding sequence.
  30. Introns
    Non-amino acid coding region between coding regions.
  31. Exons
    Expressed sequence; coded for amino acids.
  32. Capping
    A capping enzyme adds a guanine nucleotide to the 5' end of the mRNA via 5' to 5' linkage.
  33. Poly A tail
    Eukaryotic cells modify the end of the mRNA by using poly A polymerase to add a sequence of adenine to protect the end from exonulceases.
  34. mRNA splicing
    Spliceosome complexes consisting of pre-mRNA and snRNP remove introns.
  35. RNA polymerase III
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Genetics Ch. 13 Transcription
2011-11-15 21:45:53
genetics transcription DNA

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