The sequence of three nitrogen bases in dna or mrna that codes of an amino acid is called a

Codon

Explanation:

The sequence of the bases along the DNA strands act as a code which determines the sequence of amino acids to be linked to form a specific protein. Every set of three bases along the DNA strands is responsible for bringing into position a particular amino acid of a polypeptide chain. The set of a base triplet is called a codon and it codes for a particular amino acid of protein molecule. Example of such codon are AAA coding for amino acid lysine.

answer; ///i believe its: ///(embolus);

i'd say that the moon rock is about 2.2 billion years old.