In the early 1950's, the structure of DNA had become a crucial puzzle, following the discovery that DNA and not protein was the "transforming" principle. The puzzle was more intriguing because of the challenge of figuring out how a polymer composed of only 4 different "letters" could encode for a polymer such as proteins that are composed of 20 different letters. DNA is an acid, owing to the phosphate groups between each deoxyribose. The "salt" of DNA …showed first 75 words of 309 total…

…showed last 75 words of 309 total…the A - T and G - C base pairs. This complementary pairing of the bases ensures that, when DNA replicates, an exact duplicate of the parental genetic information is made. The polymerization of a new complementary strand takes place using each of the old strands as a template. For their outstanding work in discovering the double helical structure of DNA, Watson and Crick shared the 1962 Nobel Prize for Physiology and Medicine with Maurice Wilkins.