RNA Structure

Cards (25)

  • What is the secondary structure of tRNAs?
    Cloverleaf shape, “CAA” acceptor stem, 4 distinct loops
  • What is the “CAA” acceptor stem?
    Amino acid attachment point; added post-synthesis
  • What are the 4 loops in the secondary structure of tRNAs?
    D loop, Anticodon loop, Variable loop, TΨC loop
  • What does the D loop contain?
    Abundant dihydrouridine
  • What does the anticodon loop contain?
    Specific trinucleotide sequence (corresponding to an amino acid)
  • What does the TΨC loop contain?
    T, Ψ, C nucleotides (invariant)
  • What is the tertiary structure of a tRNA?
    L-shape
  • What are the base-pairing interaction that form the tertiary structure of a tRNA?
    D loop with variable and TΨC loops
  • What interactions occur within a tRNA molecule?
    Watson-Crick base pairs, Non-Watson-Crick base pairs, triple base pairs, Metal ion/polyamine binding
  • What is the purpose of metal ions/polyamines in RNA structure?
    Shield negatively charged phosphate groups, stabilize tertiary structure
  • What are some examples of divalent metal ions/polyamines?
    Mg2+ and Spermine (contains amine, NH2 groups)
  • What is the purpose of rRNAs?
    Provide structural foundation for ribosomal proteins
  • What modified nucleotides are found in rRNAs?
    Ribothymidine (T) and Pseudouridine (Ψ)
  • How are different rRNA species classified?
    Via sedimentation coefficients (prokaryotic ribosome → 70S; consists of 50S and 30S rRNA strands)
  • What is the structure of rRNAs?
    Complex secondary and tertiary structures, extremely varied sequences, structures nearly homologous
  • How can RNA molecules play a role in catalysis?
    Via hydrolytic or transesterification reactions
  • What processes the 5’-ends of a tRNA molecule?
    RNAse P (type of ribonuclease)
  • What is a ribozyme?
    A piece of RNA that is catalytic and uses either itself or another piece of RNA to cleave something
  • What is the spliceosome and what does it do?
    Multiple ribozymes; carries out splicing of introns from pre-mRNA
  • What are riboswitches?
    Regulatory segments found in ssRNA
  • What do riboswitches do?
    Turn RNAs on or off through small molecule binding
  • What do ligands bind to in riboswitches and what does that cause?
    Ligands bind to an aptamer domain leading to RNA structural changes
  • What are the two forms of regulation that riboswitches are involved in?
    Regulation of transcription and translation
  • What are aptamers?
    Sequences that form 3D structures that can be used to identify specific types of biomarkers on certain cells
  • What can ribozymes cleave?
    Self (phosphate backbone) or other pieces of RNA