Figure 6

Biochemistry and genetics merged thirty years ago. The symbol indicates the catalysed translocation of an extracellular substrate or substrates (X₃)and the subsequent intracellular catalysed transformations, including scavenging pathways, that form nucleoside triphosphate (NTP) precursors for the transcription process. Similarly, indicates the catalysed translocation of the extracellular substrates (X₂) and the subsequent synthesis from (X₂), and other intracellular substrates, of the amino acid (AA) precursors for the translation process. The enzymes subsumed as E_Ts and E_Tl are involved in the final stages of the expression (transcription and translation) of genes g1, g2, g3, g4 - - etc as polypeptides (P₁, P₂, P₃, P₄ - - etc). In diploid cells a pair of proteins will be synthesised from each pair of alleles at a gene locus. Those pairs of polypeptides (proteins) that are catalytically active in a diploid cell are represented by the single symbols E₁, E₂, E₃, E₄ - - - etc in this Figure 6. Further details are given in Section 5.5.