7.3 Translation

Essential idea:
Understandings: Nature of science:
    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 synthesize proteins for use primarily within the cell.

    Bound ribosomes synthesize 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 the polypeptide is the primary structure.

    The secondary structure is the formation of alpha helices and beta pleated sheets stabilized by hydrogen bonding.

    The tertiary structure is the further folding of the polypeptide stabilized by interactions between R groups.

    The quaternary structure exists in proteins with more than one polypeptide chain.

    Applications : Guidance:
      tRNA-activating enzymes illustrate enzyme–substrate specificity and the role of phosphorylation.
      Names of the tRNA binding sites are expected as well as their roles.

      Examples of start and stop codons are not required.

      Polar and non-polar amino acids are relevant to the bonds formed between R groups.

      Quaternary structure may involve the binding of a prosthetic group to form a
      conjugated protein.

    Skill:
      Identification of polysomes in electron micrographs of prokaryotes and eukaryotes.

      The use of molecular visualization software to analyse the structure of eukaryotic ribosomes and a tRNA molecule.

      Licence

      HL Topic 7 Nucleic acids and proteins Copyright © by Alex Black. All Rights Reserved.

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