Question

The sequence of three nucleotides that code for specific amino acids or stop signals in the synthesis of protein is called an?

Answer 1

Codon is the answer you are looking for.

Answer 2

Codon. The genetic code comprises of all the codons in the genome. Codons, other than the stop codons, code for 20 amino acids. Codons, that are comprises of three nucleotides, have a possible 64 combination from permutation computation.  61 of these combiantions code for proteins while the rest stop translation.