7.3  Translation

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Essential Idea:

Information transferred from DNA to mRNA 

is translated into an amino acid sequence


  • Initiation of translation involves assembly of the components that carry out the process
  • Synthesis of the polypeptide involves a repeated cycle of events
  • Disassembly of the components follows termination of translation
  • Free ribosomes synthesise proteins for use primarily within the cell
  • Bound ribosomes synthesise proteins primarily for secretion or for use in lysosomes
  • Translation can occur immediately after transcription in prokaryotes due to the absence of a nuclear membrane
  • The sequence and number of amino acids in a polypeptide is the primary structure
  • The secondary structure is the formation of alpha helices and beta pleated sheets stabilised by hydrogen bonding
  • The tertiary structure is the further folding of the polypeptide stabilised by interactions between R groups
  • The quaternary structure exists in proteins with more than one polypeptide chain


  • tRNA-activating enzymes illustrate enzyme-substrate specificity and the role of phosphorylation


  • Identification of polysomes in electron micrographs of prokaryotes and eukaryotes
  • The use of molecular visualisation software to analyse the structure of eukaryotic ribosomes and a tRNA molecule