Genetic engineering. Computer artwork showing a DNA (deoxyribonucleic acid) double helix being cut by a pair of scissors, next to a model of DNA's molecular structure. The scissors represent an enzyme, known as a restriction enzyme, that cuts DNA so that a new DNA section (left) can be inserted. DNA contains specific compounds called nucleotides (yellow horizontal lines at left), the sequence of which create the instructions for making proteins within a living organism. Inserting new DNA into a section of original DNA will alter the instructions from this region. This technique can be used to treat diseases such as diabetes or to add favourable features to crops and plants such as drought resistance.