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10: Translation

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    The RNA polymerase has done its job (or in the case of prokaryotes, may still be in the process of doing its job), so now what happens to the RNA? For RNA that is destined to provide instructions for making a protein, then it needs to be translated, which is a job for SupermanTM! Oops, actually it’s a job for ribosomes.

    • 10.1: Introduction to Ribosomes
      This page discusses the role of ribosomes in protein synthesis, highlighting their composition of RNA and proteins and their function in translating mRNA into polypeptides through aminoacyl-tRNA addition. It contrasts prokaryotic and eukaryotic ribosomal RNA production, noting the use of different RNA polymerases. The page emphasizes that, despite variations in ribosomal structure, the translation process is remarkably conserved among different species.
    • 10.2: Prokaryotic Ribosomes
      This page explains that prokaryotic ribosomes are composed of a small 30S and a large 50S subunit, totaling a 70S ribosome critical for translation. The small subunit locates the mRNA start site, and the large subunit links amino acids. Prokaryotic rRNA genes are organized in operons, producing a single transcript processed into functional segments by RNase III. The "S" in ribosome notation represents Svedberg units, which indicate sedimentation rates based on mass and shape.
    • 10.3: Eukaryotic Ribosomes
      This page discusses the processing of eukaryotic ribosomal RNA (rRNA) in the nucleolus, where ribosome production occurs. It outlines the structure of the ribosomal subunits, with the 40S subunit containing 1 rRNA and 33 proteins, and the 60S subunit containing 3 rRNAs and 50 proteins. It emphasizes the conservation of ribosomal RNA precursors and their modification by small nucleolar RNAs (snoRNAs).
    • 10.4: The Genetic Code
      This page details the coding of proteins by DNA and RNA through a triplet codon system that creates 64 combinations for 20 amino acids. It defines the genetic code as degenerate and non-ambiguous, highlighting redundancy due to multiple codons for single amino acids and the presence of three stop codons. AUG is identified as the start codon and methionine. Variations exist in prokaryotes and mitochondrial codes, with some rare modifications in the genetic code also mentioned.
    • 10.5: tRNA are Rather Odd Ducks
      This page explains the production and charging of tRNA in both prokaryotes and eukaryotes, highlighting the removal of leader sequences in prokaryotic tRNA and the presence of introns in eukaryotic tRNA. It discusses modifications that influence tRNA function and "wobble," which facilitates flexible codon-anticodon pairing. Additionally, it covers the role of aminoacyl tRNA synthetases in accurately attaching amino acids to tRNA, emphasizing mechanisms of discrimination and ATP energy investment.
    • 10.6: Prokaryotic Translation
      This page describes the process of translation in prokaryotes, detailing initiation with the small ribosomal subunit binding to the Shine-Dalgarno sequence, the role of initiation factors and the initiator tRNA, the elongation of the polypeptide chain with simultaneous tRNA binding, and the termination phase where release factors recognize stop codons to release the polypeptide and disassemble the ribosome.
    • 10.7: Eukaryotic Translation
      This page discusses eukaryotic translation, highlighting its similarities and complexities compared to prokaryotic processes, particularly in initiation. Eukaryotic mRNA codes for one gene, clarifying start codons. The initiation process involves a ternary complex and 5’ cap binding, forming the 43S complex for scanning start codons.
    • 10.8: Regulation of Translation
      This page explores gene expression regulation through pre-transcriptional and post-translational mechanisms. It emphasizes iron-sensitive RNA-binding proteins' role in iron management via ferritin and transferrin regulation.

    Thumbanil: Diagram of RNA translation. (CC BY 3.0 - unported; Kelvinsong).

    This page titled 10: Translation is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by E. V. Wong via source content that was edited to the style and standards of the LibreTexts platform.