Ask A Scientist© Biology Archive

 
Question:  How were the nucleotides in DNA identified and how are they decoded?  
From Daniel Redman Grade 7, Wood Oaks Junior High, Northbrook, Illinois

Answer:
One way was to use enzymes that chewed off the nucleotides one
at a time, so they could be analyzed chemically.  It was rather
quick to find out there were only four, it took longer to get the
exact structures.  To get the code, people used small sections
of DNA whose nucleotide sequence they could determine, and then
in a test tube used that DNA to make a protein.  Then they
sequences the protein for its amino acids and compared this
with the DNA nucleotide sequence to crack the code.
--ProfBill