The nitrogenous bases' sequence, which determines amino acids' sequence (which construct proteins) are called genetic codes. Although DNA is the main body of genes, it is actually mostly proteins that make the structures of the body and stimulate chemical reactions. If DNA were the plans of the bodies, then protein would be the actual workers, so all the wonderful plans would be meaningless unless transformed into protein. This means that the genetic information, or genetic codes of DNA are the instructions for making proteins.
Protein is made from the 20 different kinds of amino acids making long chains in various orders. The orders are determined by the sequence of nitrogenous bases of DNA. This means that genetic codes are the sequence of nitrogenous bases. When expressing codes in letters, the initial letters of the four nitrogenous bases, A, T, G, C are used. Three bases create one set to determine one amino acid. These three bases as a set is called a codon.
Let's look a little more closely at these codons.
In genetic codes, three nitrogenous bases create a set to express one amino acid. As already explained above, each of these sets are called codons. Each codon has its duty of creating a specific kind of protein. (Below is a table that show which codon expresses which amino acid.) Proteins are made from the instructions of DNA. But in reality, proteins are actually made from the information of messenger RNA -the copy of DNA bases.
As already explained before, various proteins are created, based on the information of codons- three bases, A, T, G, and C of DNA forming one set. Among those codons, there are certain sets that specify where to begin and end reading the sequences. Initiator codons give orders to begin the reading, and are formed by bases TAC. Terminator codons stop the reading, and are formed by bases ATC, ACT and ATT. Since mRNA, the copy of DNA, is made by the corresponding bases of DNA, the initiator codon of mRNA would be AUG, and terminator codons UAG, UGA, and UAA.
Genetic Codes:
