Next generation sequencing (NGS) uses parallel sequencing to determine the order of nucleotides, or bases, that make up DNA. Whether you sequence the whole genome or target a specific part of it, DNA sequencing using NGS provides fast and accurate data to answer almost any genomics question.
DNA contains the instructions needed to make living organisms. It is made of nucleotides which have 3 parts: a sugar, a phosphate, and a base. There are 4 main types of bases: adenine (A), thymine (T), cytosine (C), and guanine (G). The nucleotides are linked together into a chain. DNA sequencing tells us the order of the As, Ts, Cs, and Gs. The order of the bases determines what is made from the DNA instructions. The order, or sequence, tells scientists which sections of DNA encode genes that will be made into proteins and which sections will become regulatory elements. The genetic sequence determines an organism’s phenotype—what it looks like and how it functions. Changes in the sequence can cause disease.
DNA sequencing initially involved determining one small piece of an organism’s sequence at a time, like adding one piece to a jigsaw puzzle at a time. Next generation sequencing enables researchers to determine the whole genetic sequence of a sample at the same time. Imagine hundreds of people putting together the same jigsaw puzzle but without getting in each other’s way. Multiple sequencing reactions happening at the same time is called parallel sequencing.
Sequencing the entire genome of an organism is called whole genome sequencing and delivers the most comprehensive data.
Targeted next generation sequencing focuses the sequencing only on areas of interest chosen by the researcher.
Exome sequencing is a type of targeted sequencing that excludes any non-protein coding sequences (for example, introns) and only determines the sequences of the protein-coding sequences, called exons.