Summary Role of DNA in Protein Synthesis

DNA is divided into functional units called genes. A gene is a segment of DNA that codes for a functional product (mRNA, tRNA, or rRNA). Since the vast majority of genes are transcribed into mRNA and mRNA is subsequently translated into polypeptides or proteins, most genes code for protein synthesis. Through transcription and translation, the order of deoxyribonucleotide bases in the DNA determines the order of amino acids (primary structure (def)) in the proteins a particular organism is capable of making. Since certain amino acids in a protein interact with other amino acids in that protein, the order of amino acids for each protein ultimately determines its final three-dimensional shape, that is, its secondary (def) and tertiary (def) structure. That molecular shape, in turn, determines the function of that protein, eg, what substrate an enzyme interacts with.

When mutation (def) or genetic recombination (def) causes a change in the order of nucleotide bases, the order of nucleotide base in an existing gene may change, coding for a new gene product. The addition of new genes to a bacterium as a result of genetic recombination can enable a bacterium to make new gene products.