Bacterium in 35S medium Bacterium in 32P medium Phage(unlabeled) Progeny phage with 35s-labeled protein Progeny phage Labeled phage with unlabeled and unlabeled DNA progeny released protein and 32P-labeled DNA Labeled protein Unlabeled stays outside, Infects unlabeled protein stays unlabeled bacteria outside,labeled DNA enters cell DNA enters cell Progeny phage Progeny phage virtually unlabeled strongly labeled (less than 1%of (more than 30% original 35s of original 32P recovered) recovered) Hershey A D和Chase M(1952)用同位素32P和35S验证DNA是遗传物质Hershey A D和Chase M（1952）用同位素32P和35S验证DNA是遗传物质