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Protein Synthesis in Anatomy & Physiology

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Terms in this set (20)

  • What is a triplet in the genetic code?
    A triplet is a sequence of 3 nucleotides in DNA that codes for an amino acid, start, or stop signal.
  • How many possible triplets are there in DNA?
    There are \(4^3\) = 64 possible triplets.
  • What does it mean that the genetic code is degenerate?
    More than one triplet can code for the same amino acid, making the DNA code degenerate.
  • What is a gene?
    A gene is a region of DNA coding for the synthesis of a protein (gene product).
  • What are the two main steps of protein synthesis?
    Protein synthesis involves transcription (DNA to mRNA) and translation (mRNA to protein).
  • What happens during transcription?
    DNA partially unwinds, and the sense strand is used as a template to transcribe triplets into mRNA codons by RNA polymerase.
  • What base pairing rules occur during transcription?
    A pairs with U, T pairs with A, G pairs with C, and C pairs with G in mRNA.
  • What are exons and introns?
    Exons are coding regions used to make protein; introns are noncoding and not used.
  • What happens during mRNA splicing in eukaryotes?
    Introns are deleted and exons rejoin to form processed mRNA, which is sent to ribosomes.
  • What are the three binding sites on the ribosome during translation?
    The ribosome has A (aminoacyl), P (polypeptidyl), and E (exit) sites.
  • What is the start codon for protein synthesis?
    The start codon is AUG, which signals the beginning of protein synthesis.
  • How does tRNA function in translation?
    tRNA brings amino acids; the first binds to the P site, the second to the A site, and peptide bonds form between amino acids.
  • What happens to tRNA during translation elongation?
    The first tRNA is released at the E site, the second translocates to the P site, and a new tRNA binds to the A site.
  • How does translation terminate?
    Translation stops when the ribosome reads a stop codon (UAA, UAG, UGA), releasing the completed protein.
  • What are the two business ends of tRNA?
    tRNA has an amino acid attachment site at the 3' end and an anticodon complementary to the mRNA codon.
  • What are polyribosomes?
    Polyribosomes are many ribosomes on the same mRNA, making multiple copies of a protein simultaneously.
  • What is the role of RNA polymerase in transcription?
    RNA polymerase synthesizes mRNA by reading the DNA template strand.
  • What is the sense strand in DNA?
    The sense strand is the DNA strand used as a template for mRNA synthesis.
  • What is the significance of the 5' to 3' direction in transcription?
    mRNA is synthesized in the 5' to 3' direction complementary to the DNA template strand.
  • Why is mRNA processing important in eukaryotes?
    mRNA processing removes introns and joins exons to produce a mature transcript ready for translation.