Outline of DNA Sequencing

DNA sequencing defined as determining the order of the four chemical building blocks called bases that make up the DNA molecule. The sequence provides information to scientists about the type of genetic data that is contained in a certain DNA segment. 

The four chemical bases of the DNA double helix always associate with the same partner to produce "base pairs." Adenine (A) always pairs with thymine (T) and cytosine (C) always pairs with guanine (G). This pairing is the basis for the mechanism by which DNA molecules are copied when cells divide, and the majority of DNA sequencing research employs this idea. Approximately 3 billion base pairs that make up the human genome encode the instructions for creating and maintaining an individual human. Despite the fact that widespread DNA sequencing in medical centres is still years away, certain major hospitals have started using sequencing to identify and treat selective disorders.

Three generations of sequencing technologies have been developed since 1977. Maxam and Gilbert's method actually gave rise to first-generation sequencing but it was Sanger's chain termination technique that marked a significant turning point in the development of DNA sequencing technology. Later, second and third generation sequencing technologies commonly referred to as next generation sequencing technology showed advancement dramatically. There are several types of sequencing platforms available for second generation sequencing, including GS FLX by 454 Life Sciences/Roche Diagnostics, Genome Analyzer, HiSeq, MiSeq and NextSeq by Illumina, Inc., SOLiD by ABI, and Ion Torrent by Life Technologies While, HelicosTM Genetic Analysis System by SeqLL, LLC, SMRT Sequencing by Pacific Biosciences, Nanopore sequencing by Oxford Nanopore's, Complete Genomics by Beijing Genomics Institute, and GnuBIO by BioRad to mention a few, are the platforms offered for third generation sequencing.

Multiple paradigm shifts have occurred within a few decades in the history of the development of DNA sequencing technologies. Sequencing technology has improved throughout time while also becoming more affordable due to advances in molecular biology, automation and sequencing methods. This has made it possible to read DNA with hundreds of base pairs in length and create gigabytes of data in a single run. Also, allowed researchers to move from pouring gels to executing programs. DNA sequencing was just developed 40 years ago and its technology will probably continue to advance over the ensuing decades and centuries. We forecast that DNA sequencing will have a lifetime impact on society comparable to or greater than the microscope, based on how swiftly technology has altered biomedical research and is starting to transform clinical medicine.

Let's look at an outline of the sequencing chemistry and the idea behind these high throughput sequencing technologies.

References:

1. Ambardar S, Gupta R, Trakroo D, Lal R, Vakhlu J. High Throughput Sequencing: An Overview of Sequencing Chemistry. Indian J Microbiol. 2016 Dec;56(4):394-404.

2. Liu L, Li Y, Li S, Hu N, He Y, Pong R, Lin D, Lu L, Law M. Comparison of next-generation sequencing systems. J Biomed Biotechnol. 2012;2012:251364.

3. Heather JM, Chain B. The sequence of sequencers: The history of sequencing DNA. Genomics. 2016 Jan;107(1):1-8.

4. França LT, Carrilho E, Kist TB. A review of DNA sequencing techniques. Q Rev Biophys. 2002 May;35(2):169-200.