Protein Synthesis Process
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Questions and Answers

What is the role of tRNA during protein synthesis?

  • To synthesize RNA
  • To carry amino acids to the ribosome (correct)
  • To degrade mRNA
  • To transcribe DNA into RNA

    • According to Crick's adaptor hypothesis, what carries the amino acid to the RNA template?

  • DNA
  • tRNA (correct)
  • mRNA
  • rRNA

    • What are the components involved in the ribosome for protein synthesis?

  • Proteins and RNA molecules (correct)
  • Proteins and lipids
  • Only proteins
  • Only RNA molecules

    • Which statement best describes the genetic code?

    <p>It is nearly universal and degenerate</p> Signup and view all the answers

    How do mRNA codons base pair with tRNA anticodons?

    <p>Via hydrogen bonding</p> Signup and view all the answers

    How many amino acids are there in proteins according to the genetic code?

    <p>20</p> Signup and view all the answers

    What is significant about the start and stop signals in the genetic code?

    <p>They are essential for the initiation and termination of translation</p> Signup and view all the answers

    Which amino acids are specified by a single codon?

    <p>Methionine and Tryptophan</p> Signup and view all the answers

    Study Notes

    Protein Synthesis

    • Occurs in a large macromolecular assembly called the ribosome, composed of many proteins and several RNA molecules
    • Involves tRNAs that interact with mRNA and are charged with one of the 20 common amino acids by 20 different aminoacyl tRNA synthetases
    • Requires a dozen or more additional protein factors for initiation, elongation, and termination of translation
    • Involves perhaps 100 additional enzymes that carry out a variety of modifications with many proteins

    Crick's Adaptor Hypothesis

    • Proposed by Francis Crick in the early 1950s, recognizing that protein sequence is encoded by the nucleotide sequence
    • Suggests that the template is RNA (maybe rRNA), and the amino acid is carried to the template by an adaptor
    • Adaptors may contain nucleotides

    Properties of the Genetic Code

    • Composed of nucleotide triplets (three nucleotides)
    • Non-overlapping, meaning each nucleotide is part of only one codon
    • Comma-free, meaning there are no punctuation marks
    • Ordered, meaning similar amino acids are specified by related codons
    • Contains start and stop signals
    • Nearly universal, meaning the same code is used in all organisms
    • Degenerate, meaning there is redundancy but no ambiguity

    Codons

    • Written in the 3' → 5' direction
    • The 3nt base is less important
    • Only Met and Trp have a single codon
    • Some codons are better than others because of the abundance of such tRNAs

    mRNA Codons and tRNA Anticodons

    • The codon sequence is complementary with the anticodon sequence
    • The codon in mRNA base pairs with the anticodon in tRNA via hydrogen bonding
    • The alignment of two RNA segments is antiparallel

    The Genetic Code

    • A non-overlapping code, with each amino acid, plus polypeptide initiation and termination, specified by RNA codons, composed of three nucleotides
    • Each of the 20 amino acids in proteins is specified by one or more nucleotide triplets in mRNA
    • Of the 64 possible triplets, 61 specify amino acids and 3 signal chain termination
    • The code is non-overlapping, with each nucleotide part of a single codon

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    Description

    Learn about the process of protein synthesis, including the role of ribosomes, tRNAs, mRNA, and various enzymes in building amino acid chains.

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