Hammerling experiment - determined where cells kept hereditary material

• used Acetabularia cells, found that hereditary material in foot area
• transplanted different parts of A. mediterranea and A. crenulata
• parts eventually developed according to the hereditary material in foot area (intermediate head formed at first due to remaining RNA left in stalk)

transplantation experiments - added support that nucleus contained hereditary material 

• Thomas King/Robert Briggs - transplanted nuclei from frog cells
  • cells wouldn’t develop w/o nucleus
  • showed that nuclei contained the information needed to direct development
• F. C. Steward - mixed fragments of carrot tissue w/ liquid growth medium
  • showed that single cells can form entire, mature plants
  • totipotent - containing full set of hereditary instructions

Griffith experiment - discovered transformation  

• found that S. pneumoniae bacteria could only infect w/ polysaccharide coating
• dead bacteria w/ polysaccharide coating mixed w/ live bacteria w/o polysaccharide coating to form live bacteria w/ polysaccharide coating
• transformation - transfer of genetic material from one cell to another

Avery experiments - found the “transforming principle” from Griffith ’s experiments 

• removed nearly all of the protein in S. pneumoniae, but transformation still occurred
• purified mixture contained elements close to that of DNA, had same density
• taking out lipids/proteins didn’t stop transformation
• DNA-digesting enzyme DNase stopped all transformations
• showed that DNA provided hereditary material for bacteria

Hershey-Chase experiment - studied bacteriophages, viruses that infect bacteria 

• viruses - contain DNA or RNA surrounded by protein coat
  • causes cells to produce so many viruses that it bursts (lyses)
• used radioactive isotopes to track DNA and protein coat
• showed that DNA caused changes in cells, not protein