What Is DNA Sequencing

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∟What Is DNA Sequencing

Provides a quick introduction of DNA sequencing, or gene sequencing, which is the process of determining the nucleic acid sequence. Two major DNA sequencing technologies are Sanger Sequencing and NGS (Next-Generation Sequencing).

What Is DNA Sequencing? - DNA sequencing, also called gene sequencing, is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine.

Here are two major DNA sequencing technologies:

1. Sanger Sequencing is based on the chain-termination method developed by Frederick Sanger to determine the sequence of nucleotide bases in a given DNA.

Sanger Sequencing uses dideoxynucleotide triphosphates in PCR (Polymerase Chain Reaction) process to terminate synthesis reactions in 4 separate reaction mixtures.

All DNA fragments generated in a single reaction mixture are terminated at the same nucleotide base type and are electrophoresed with a unique color.

Then all DNA fragments from all reaction mixtures are blended together, sorted and identified by gel electrophoresis to reconstruct the order of nucleotides of the original DNA.

2. NGS (Next-Generation Sequencing) is based on genome sequence alignment algorithm to the sequence of nucleotide bases of any DNA from a given sample.

NGS breaks chromosomes or long DNAs into millions of DNA fragments. Then the order of nucleotide bases in each DNA fragment is determined and aligned to a reference gene sequence.

When all DNA fragments are processed, sample's DNA sequence is constructed by reading nucleotide bases from DNA fragments aligned the same reference gene sequence.