The Avery–MacLeod–McCarty experiment was an experimental demonstration by Oswald Avery, Colin MacLeod, and Maclyn McCarty that, in 1944, reported that DNA is the substance that causes bacterial transformation, in an era when it had been widely believed that it was proteins that served the function of carrying genetic information. It was the culmination of research in the 1930s and early 20th century at the Rockefeller Institute for Medical Research to purify and characterize the "transforming principle" responsible for the transformation phenomenon first described in Griffith's experiment of 1928: killed Streptococcus pneumoniae of the virulent strain type III-S, when injected along with living but non-virulent type II-R pneumococci, resulted in a deadly infection of type III-S pneumococci. In their paper "Studies on the Chemical Nature of the Substance Inducing Transformation of Pneumococcal Types: Induction of Transformation by a Desoxyribonucleic Acid Fraction Isolated from Pneumococcus Type III", published in the February 1944 issue of the Journal of Experimental Medicine, Avery and his colleagues suggest that DNA, rather than protein as widely believed at the time, may be the hereditary material of bacteria, and could be analogous to genes and/or viruses in higher organisms.
Oswald Avery
Colin MacLeod
Maclyn McCarty (with Watson and Crick)
Francis Crick
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Francis Harry Compton Crick was an English molecular biologist, biophysicist, and neuroscientist. He, James Watson, Rosalind Franklin, and Maurice Wilkins played crucial roles in deciphering the helical structure of the DNA molecule.
Diagram that emphasises the phosphate backbone of DNA. Watson and Crick first made helical models with the phosphates at the centre of the helices.
Crick and Watson DNA model built in 1953, was reconstructed largely from its original pieces in 1973 and donated to the National Science Museum in London.
Results from an fMRI experiment in which people made a conscious decision about a visual stimulus. The small region of the brain coloured orange shows patterns of activity that correlate with the decision making process. Crick stressed the importance of finding new methods to probe human brain function.