Genetically engineered maize Conceptual computer illustration of a DNA autoradiogram superimposed on a genetically modified GM corn cob DNA deoxyribonucleic acid is the molecule which controls the development and growth of all living things It is made up of two strands linked by a sequence of bases Autoradiograms are a way of studying DNA which show the positions of DNAs bases as black bands Corn or maize Zea mays is a crop grown in the warmer parts of the world Genetic engineering involves altering an organisms DNA to impart beneficial traits In crops these often increase resistance to diseases or protect the plants from weedkillers