Proteins are long chains of individual amino acid subunits. The order of the amino acids in the chain is determined by the DNA sequence of the gene that encodes for it. This is commonly referred to as the genetic code.
DNA is a chain of four different nucleotides (adenine, thymine, cytosine, and guanine), often abbreviated A, T, C, and G. These four nucleotides (sometimes referred to as bases) give the instructions for the 20 different amino acids that compose proteins. Each amino acid is encoded by a sequence of three DNA bases, called a codon. Since it takes three DNA bases to designate an amino acid, there are enough combinations of the four different bases to represent all of the amino acids, as well as three stop codons that indicate when the protein ends. Each base can be in any position, which yields 43, or 64, possible combinations, so there is some redundancy between the 20 amino acids. This just means that a given amino acid can be encoded by more than one DNA codon sequence.
For simplicity, individual amino acids are often abbreviated using one or three letter abbreviations. For example, the amino acid arginine can be abbreviated Arg or R. The single-letter amino acid abbreviations provide a fun way to write secret messages using the genetic code. Since there are only 20 different amino acids, there are 6 letters of the alphabet that don’t stand for a specific amino acid. With the 20 letters that do, however, you can use the genetic code to determine the DNA sequence that corresponds to your amino acid message.
The message can be written with four different colors that represent the four different bases that make up DNA. The chain in the picture at the top of the page has this sequence:
The sequence starts with RYG. Using the color key in the Assembly section, this corresponds to the bases ATG, which is the methionine start codon that begins every protein sequence. Can you decode the rest of the message?