People who study genes today understand mutations as a change in the order of deoxyribonucleic acid or DNA. DNA is made up of individual units called nucleotides. These nucleotides form long spiraling chains. The location of nucleotides along the dna chain determines the characteristics of an organism. dna provides the genetic information for living organisms in the same way that the hard drive of a computer carries information. Just as a picture on a computer screen becomes distorted when one changes its digital coding, a mutation happens when a specific sequence of dna is altered. mutations may involve the removing or changing of only one or a few nucleotides. the result, however, may be very dramatic.