DNA research. Conceptual image of a gloved hand holding a DNA (deoxyribonucleic acid) molecule in a test tube, representing genetic research. The DNA double helix is composed of two twisting sugar-phosphate strands linked by pairs of nucleotide bases. The sequence of the bases encodes genetic information. Below the tube is a gel showing the results of Sanger sequencing, a laboratory technique to find out the sequence of a length of DNA. The sequence of the four bases can be read from the four columns of lines.