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Unformatted text preview: xperiment” http://www.urbanhonking.com/digest/archives/blender.jpg http://www.ndpteachers.org/perit/Chase%20&%20Hershey%201953.JPG 11 viruses that infect bacteria Bacteriophages 12 13 Is DNA or protein the genetic material? Experiment: 1. Label protein (mostly viral coat) with 35S (radioactive) 2. Allow infection of E. coli 3. Put in blender and centrifuge (separate virus from bacteria) 4. Where is the radioactivity?
14 Is DNA or protein the genetic material? Experiment: 1. Label DNA with 32P (radioactive) 2. Allow infection of E. coli 3. Put in blender and centrifuge 4. Where is the radioactivity?
15 Hershey/Chase Data
Total isotope in supernatant (%)
Extracellular 35S Extracellular 32P Agitation time in blender (min) 16 A DNA model
X-ray diffraction of DNA James Francis Rosalind Watson Crick Franklin Maurice Wilkins DNA forms a double helix: two strands of DNA, base paired, twisted around each other 17 Chargaff ’s Rules
30.3% A 30.3% T 19.5% G 19.9% C 18 DNA structure
"It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the g...
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