DNA Sequencing

DNA sequencing is the process of determining the exact order of nucleotides within a DNA molecule. It includes any method or technology that is used to determine the order of the four bases—adenine, guanine, cytosine, and thymine—in a strand of DNA. The advent of rapid DNA sequencing methods has greatly accelerated biological and medical research and discovery. DNA sequencing is used for a variety of applications, including determining the sequence of genes and their associated proteins, as well as studying the structure and function of genomes. It is also used to diagnose genetic diseases, to analyze the evolutionary relationships between species, and to create personalized medicine. The most common DNA sequencing method today is Sanger sequencing, which relies on the synthesis of DNA strands by the enzyme DNA polymerase. In this method, a primer is annealed to a single-stranded DNA template, and then DNA polymerase adds nucleotides one at a time. As each nucleotide is added, the DNA fragments into different lengths. These fragments are then separated by size through gel electrophoresis and the sequence is determined by sequencing the DNA fragments from the 5′ end to the 3′ end. More recently, next-generation sequencing (NGS) technology has been developed, which allows for the parallel sequencing of many DNA molecules at once. This technology uses various sequencing strategies, including sequencing by synthesis, sequencing by ligation, and single-molecule sequencing.