1 nt/a.a.A,G,T,C (4 combinations)2 nt/a.a.AA,AG, AT,ACGA, GG, GT, GCTA, TG, TT, TCCA,CG,CT,CC(4x4-16 combinations)3 nt/a.a.AAA,AAG,AAT,AACAGA.AGG.AGTAGCATA. ATG. ATT, ATCACA, ACG, ACT, ACCGAA, GAG, GAT, GACGGA, GGG, GGT, GGCGTA, GTG, GTT, GTCGCA, GCG, GCT, GCC.....(4x4x4=64combinations)8-6
8-6 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display 1 nt/a.a. A, G, T, C (4 combinations) 2 nt/a.a. AA, AG, AT, AC GA, GG, GT, GC TA, TG, TT, TC CA, CG, CT, CC (44=16 combinations) 3 nt/a.a. AAA, AAG, AAT, AAC AGA, AGG, AGT, AGC ATA, ATG, ATT, ATC ACA, ACG, ACT, ACC GAA, GAG, GAT, GAC GGA, GGG, GGT, GGC GTA, GTG, GTT, GTC GCA, GCG, GCT, GCC . (444=64 combinations)
(a)Colinearityofgenesandproteins1m.u.GeneticmapfortrpAmutationNCPosition of alteredaminoacidintrpApolypeptide23449211115222681LysGluGlyGlyAminoacid in wild-typepolypeptide个.-GluASPCysSTOPArgAminoacidinmutantpolypeptideVal GlnMet(23)(46)(78)(58)(mutantnumber)(b)Recombinationwithinacodon0.001m.u.0.001m.u.codonforcodonforaa211aa234trpA-mutant(Arg)trpAmutant(Cys)2378trpA-mutant(Glu)trpA-mutant(Asp)4658trpA+wild-typerecombinant(Gly)trpA+wild-typerecombinant(Gly)codonforcodonforaa234aa211Fig.8.48-7
8-7 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Fig. 8.4
InterpretationoftheresultsA codon is composed of more than one nucleotideDifferent point mutations may affect the same amino acid.Each nucleotide is part of only a single codon.Each point mutation altered only one amino acid8-8
8-8 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display A codon is composed of more than one nucleotide. is composed of more than one nucleotide. Different point mutations may affect the same amino acid. Different point mutations may affect the same amino acid. Each nucleotide is part of only a single Each nucleotide is part of only a single codon. Each point mutation altered only one amino acid. Each point mutation altered only one amino acid. Interpretation of the results
Evidence fora triplet code1955-Francis Crick and SydneyBrennerGenerate mutations of bacteriophage T4rllB gene withproflavin.LifeIrcienceSydneyBrennerFrancisCrickSydneyBrenner(1916-2004)(1927-)8-9
8-9 Copyright © The McGraw-Hill Companies, Inc. Permission required to reproduce or display Evidence for a triplet code 1955 – Francis Crick Francis Crick and Sydney Brenner Sydney Brenner Generate mutations of Generate mutations of bacteriophage bacteriophage T4 rIIB gene with gene with proflavin proflavin. Francis Crick (1916-2004) Sydney Brenner (1927-)
E.coli strainT4strainBK(2)rll+rll-NoplaquesLarge,distinctrll+rll+Small, fuzzySmall, fuzzy8-10
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