DNA Sequencing Techniques: Sanger Sequencing vs Next Generation Sequencing (NGS)

DNA sequencing

the process of determining the nucleic acid sequence (order of four nucleotides in DNA)Walter Gilbert developing the chemical degradation method.

DNA sequencing is the process of determining the precise order of nucleotides (adenine, guanine, cytosine, and thymine) in a DNA molecule. This process provides valuable genetic information as it reveals the genetic blueprint of an organism. There are various techniques used for DNA sequencing, but the most popular ones are Sanger sequencing and Next Generation Sequencing (NGS).

Sanger sequencing, also known as chain termination sequencing, is a traditional method of DNA sequencing that was first developed in 1977 by Frederick Sanger. In this technique, a DNA sample is copied many times, and the copies are terminated at specific points by incorporating fluorescent dideoxynucleotides (ddNTPs) into the reaction. The ddNTPs are labeled with different fluorescent dyes and allow the detection of the specific base at each termination point. By analyzing the pattern of colors produced, the sequence of the DNA fragment can be determined.

Next Generation Sequencing (NGS) is a modern method of high-throughput DNA sequencing that overcomes the limitations of Sanger sequencing. NGS technology allows the sequencing of millions of fragments of DNA simultaneously, resulting in a significantly higher throughput. The most common NGS platforms include Illumina, Ion Torrent, PacBio, and Nanopore.

NGS typically involves fragmenting the DNA sample, attaching adapters to the fragments, and then immobilizing them on a solid support. The DNA fragments are then amplified, and the sequencing reactions are carried out in parallel on the solid support using one of several different methods, depending on the platform being used. The output data is processed using various bioinformatics tools to generate a complete DNA sequence.

Overall, DNA sequencing plays a crucial role in numerous scientific applications such as genetic disease diagnosis, drug development, crop improvement, and forensic science.

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