The genetic code of a dna molecule is determined by a specific sequence of

Nucleotide bases

Explanation:

The genetic code is the way by which information on a gene is encoded. It comprises of all the codons that encodes an amino acid in all living organisms. A codon is a group of three nucleotides sequences on the mRNA that corresponds an amino acid.

The genome of an organism is inscribed in Deoxyribosenucleic acid (DNA). The segment of this DNA that codes for a protein or an RNA is referred to as a gene. Those genes that code for proteins are composed of tri-nucleotide units called codons, each coding for a single amino acid. Each nucleotide sub-unit consists of a phosphate, deoxyribose sugar and one of the 4 nitrogenous nucleotide bases (A, G, C and T). The specific order of these nucleotide bases is what determines DNA's instructions or GENETIC CODE i.e. the order of the bases in the DNA specifies the order of bases in the mRNA and the order of bases in the mRNA specifies the order amino acids in the protein.