Deoxyribonucleic Acid, or more commonly known as DNA, is a nucleic acid containing the genetic instructions to all living organisms. DNA, along with other forms of nucleic acids (such as RNA and proteins) are macromolecues necessary to sustain all life.
DNA plays a very important role in society of the not-too-far future in the 1997 science fiction movie Gattaca. It is basically used to determine one's life, as many things in life will depend on a their genetic makeup.
While Vincent Freeman is working at Gattaca Aerospace Corporation under the name of Jerome Morrow, he must take numerous tests so the corporation knows that he is a "Valid" employee, as jobs are given to people based on DNA. Vincent was born with many mutations in his DNA, and he must buy the DNA of Mr. Morrow in order to get into Gattaca.