DNA synthesizers are machines used to custom-build DNA molecules to contain a particular sequence of nucleotides. DNA synthesizers can create specific DNA molecules for use in the treatment of a variety of diseases by replacing a faulty or damaged section of DNA with a repaired section.DNA synthesizers use methods developed by scientists conducting the Human Genome Project. The Human Genome Project provided a map of the entire human genome, enabling scientists to decipher specific sequences of nucleotides that are responsible for certain types of protein synthesis in the body. DNA synthesis is the process of copying a strand of DNA in a biological cell before the cell replicates or divides. Since the base pairs in DNA always contain the same two complementary nucleotides - adenine always bonds with thymine, and cytosine always bonds with guanine - DNA synthesizers can built DNA molecules using one strand of DNA as a blueprint and then use DNA protein synthesis to repair any discrepancies in the strand.DNA sequencers are DNA synthesizers that are used to analyze the sequence of nucleotides in a DNA sample. A DNA sequencer is often used to analyze DNA evidence from a crime scene to provide a definitive DNA fingerprint of a potential suspect. DNA sequencing is accomplished most often by the dideoxy, or chain termination method. In this method, normal DNA protein synthesis is interrupted periodically by the introduction of a compound called deoxynucleotide triphosphate, which is substituted as the DNA chain is elongated by the addition of the normal nucleotides. These dideoxy compounds fluoresce under examination by a laser beam, functioning like tags to mark out specific sections of the DNA molecule. Each section or DNA sequence can then be separated and analyzed.DNA synthesizers are available from several biological instrument manufacturers. DNA synthesizers may be programmable to handle batch analysis and are typically differentiated by cycle times and sample capacity and purity. A DNA synthesizer may also be PC compatible, allowing operators to monitor processes through a web browser.