Treat with Treat with deoxyribonuclease ribonuclease Treat with protease ↓ Assay for Transformation IIR cells IIR cells IIR cells IIR cells DNase-treated RNase-treated Protease-treated IlIS filtrate IlIS filtrate llIS filtrate IllS filtrate No transformation Transformation Transformation Transformation occurs occurs occurs occurs Only IIR IIR cells IIR cells IIR cells cells 十 lIS cells ‖ s cells IlIS cells Conclusion Conclusion Conclusior Control active factor is dNa active factor active factor IllS contains ‖ s cells is not rna is not protein active factor Ⅲ R cells (Klug Cummings 1997) Biochemical assays for transformation Avery combined living IIR bacteria with various enzymatic treatments of killed IlIS material that selectively destroy protein, RNA, and DNA. Only the last treatment destroys the transformative capacity of IllS, which suggests that the transforming substance is DNA
Biochemical assays for transformation Avery combined living IIR bacteria with various enzynmatic treatments of killed IIIS material that selectively destroy protein, RNA, and DNA . Only the last treatment destroys the transformative capacity of IIIS, which suggests that the transforming substance is DNA
Hershey Chase(1952)-blender experiment bacteriophages are grown in radioactive medium proteins labeled with 35S DNA labeled with 32P during transformation of E coli by bacteriophages 32P goes in, 35S stays out DNA is the transforming principle
Hershey & Chase (1952) - 'blender experiment' bacteriophages are grown in radioactive medium proteins labeled with 35S DNA labeled with 32P during transformation of E. coli by bacteriophages, 32P goes in, 35S stays out => DNA is the transforming principle
a1 phage 0.2um 论e T1 Bacteriophages("Phage") Bacteriophages are viruses that attack bacteria. They attach to the outside membrane of bacteria by means of the thin "tail". the round head"contains dNA. The name means"bacteria eaters"and is commonly shortened to just"phage". Early biochemical and genetic studies of phage are the foundations of modern molecular biology
T1 Bacteriophages ("Phage") Bacteriophages are viruses that attack bacteria. They attach to the outside membrane of bacteria by means of the thin "tail": the round "head" contains DNA. The name means "bacteria eaters" and is commonly shortened to just "phage". Early biochemical and genetic studies of phage are the foundations of modern molecular biology
置 Phage T2(unlabeled Phage added to E coli in radioactive medium 32 35 Progeny phages become labeled (Klug Cummings 1997) The Hershey Chase Experiment Growing bacteriophage(a virus that grows on bacteria) was differentially labelled with radioactive (which labels )or radioative (which labels
The Hershey & Chase Experiment Growing bacteriophage (a virus that grows on bacteria) was differentially labelled with radioactive phosphorus (which labels nucleic acid) or radioative sulfur (which labels protein)
(Klug &Cummings 1997) Labeled phage infect unlabeled bacteria Separation of phage ghosts"from . bacterial cell 皇 Phage“ ghosts Phage"gh osts" are Infected bacterium are unlabeled Intected bacterium labeled with 35s are unlabeled Viable phage produced Viable unlabeled labeled with <P phage produced The Hershey Chase Experiment During the process of infection, a quick spin in a blendor shears phage away from the outside of the bacteria. Analysis of the bacterial and supernatant fractions afterward shows that phosphorus-abelled DNA inside the phage shows up in bacteria(left) whereas the in the external coat remains in the supernatant (right). Further, bacteria with labelled dNa go on to produce progeny phage that are also labelled. This biological experiment confirms Avery,'s conclusion that DNA is the transforming substance, and shows that transformation is heritable
The Hershey & Chase Experiment During the process of infection, a quick spin in a blendor shears phage away from the outside of the bacteria. Analysis of the bacterial and supernatant fractions afterward shows that phosphorus-labelled DNA inside the phage shows up in bacteria (left), whereas the sulfur-labelled protein in the external coat remains in the supernatant (right). Further, bacteria with labelled DNA go on to produce progeny phage that are also labelled. This biological experiment confirms Avery's conclusion that DNA is the transforming substance, and shows that transformation is heritable