the hunt for fame fortune and dna chapter 13.1 ap biology fall 2010
TRANSCRIPT
The Hunt for Fame Fortune and DNA
Chapter 13.1
AP BiologyFall 2010
Early and Puzzling CluesJohann Miescher is credited with the
discovery of DNA in the late 1800’s
Early and Puzzling CluesIn 1928, Fred Griffith was working with S
(pathogenic) and R (nonpathogenic) strains of a pneumonia-causing bacteriumInjected mice with R cells; mice livedInjected mice with S cells; mice died
Blood samples contained many live S cellsS cells were heat-killed, then injected into
mice; mice livedLive R cells plus heat killed S cells were
injected into mice; mice diedLive S cells were found in blood
Griffith Experiments
Early and Puzzling CluesSome substance from the S cells had
transformed the R cellsBoth proteins and nucleic acids were
candidates In 1944, Oswald Avery showed the substance
was DNA
Avery Experiments
Confirmation of DNA FunctionViruses called bacteriophages use bacterial
cells for reproduction Because they consist of only a protein coat
and a nucleic acid core, these viruses were used in experiments by Hershey and Chase to prove which of these was the heredity material It was the nucleic acid
Confirmation of DNA Function35S labeled proteins in the bacteriophage
coat did not enter the bacteria and thus were not participating in providing directions for new virus assembly
32P labeled DNA in the viral core did not enter the bacteria and directed new virus assembly
Confirmation of DNA FunctionLinus Pauling deduced the structure and
secrets of the protein collagen, bringing the biology community one step closer to DNA structural details
Enter Watson and CrickWatson and Crick used numerous sources
of data to build various models of DNAIn 1953, they discovered and published the
structure of DNA