Saturday, April 2, 2011

DNA: Hereditary Material – People and History

1869—Friedrich Miescher
-extracted white substance (DNA) from nucleus and called it nuclein
-found that its properties differed from those of proteins

1908—T.H. Morgan
-experimented with Drosophilia (fruit flies) and associated phenotype with a specific chromosome
-concluded that genes are found on chromosomes

1920’s—Frederick Griffith
-used mice and two strands of pneumococcus bacteria (virulent/non-virulent)
-found that when heat treated virulent bacteria (denatured proteins) was mixed with healthy non-virulent bacteria and was injected into mice, these mice died
-caused people to suspect that DNA, not proteins in chromosomes, is responsible for inheritance
-discovered process of transcription

1930’s—Joachim Hammerling
-used Acetabularia (A. crenulata and A. medittarnea: long cells with nucleus located at the base) to prove that material in nucleus is responsible for heredity
-chopped off top, regenerated
-chopped off bottom, no regeneration

1944—Avery, McCarty, MacLeod
-separated DNA and proteins from chromosomes of streptococcus pneumonia bacteria
-injected DNA and proteins into separate bacteria
-bacteria with DNA injected became virulent
-more support that DNA contains genetic information

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