normal red straight straight long red gray long long long eyes wings wings wings eyes body legs wings aristae 5 tarsi 104 99.2 75.5 545 485 31 13 tars brown arc bent curved vestigial purple black dachs dumpy aristaless eyes wings wings wings eyes body (short legs) wings (short aristae】 1-8 mutant The genetic map of chromosome 2 of Drosophila melanogaster
The genetic map of chromosome 2 of Drosophila melanogaster
In 1931,Harriet Creighton Barbara McClintock found the evidence of gene recombination Barbara McClintock.(Source:Bettmann Archive.)
In 1931, Harriet Creighton & Barbara McClintock found the evidence of gene recombination
What's the nature of genetic material? 1928,Frederick Griffith:transformation in bacteria:Streptococcus pneumoniae 1944,Oswald Avery,Coli Maclyn McCarty confirme transforming material Figure 1.7 Oswald Avery.(Source:National Academy of Sciences.)
What’s the nature of genetic material？ 1928, Frederick Griffith: transformation in bacteria: Streptococcus pneumoniae 1944, Oswald Avery, Colin MacLeod, and Maclyn McCarty confirmed that, DNA, the transforming material
Strain of Strain of Colony Colony Cell type Effect Cell type EMect -Capsule No capsule 小 Smooth(S) Rough (R) Live R strain strain (a) Eect 8889 Live R strain Heat-killed Heat-killed S strain Sstrain Live S and R strains isolated from dead (d) mouse Figure 2.2 Griffith's transformation experiments.(a)Virulent strain SS.pneumoniae bacteria kill their host:(b)avirulent strain R bacteria cannot infect successfully,so the mouse survives;(c)strain S bacteria that are heat-killed can no longer infect:(d)a mixture of strain R and heat-killed strain S bacteria kills the mouse.The killed virulent(S)bacteria have transformed the avirulent(R)bacteria to virulent(S)
Cells extracted Centrifuge Heat-kill and opened IS cells llISin liquid culture IlIS soluble medium filtrate salvaged DNase RNase Protease Transforming Transforming Transforming power testec power tested power tested lIR cells lIR cells lIR cells IIR cells DNase-treated filtrate IllS filtrate RNase-treated IllS filtrate Protease-treated IlIS filtrate Transformation testing Only IIR lIR cells lIR cells lIR cells 4 cells IlIS cells lllS cells llIS cells Negative Positive Positive Positive CONCLUSION CONCLUSION: CONCLUSION: CONTROL: active factor active factor IllS cells produced is not RNA is not protein FIGURE 8.4 Summary of Avery,MacLeod,and McCarty's experiment demonstrating that DNA is the transforming principle