dna four bases

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 …

…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.