How Does DNA Sequencing Work?

One of the ways that scientists and biological researchers have learned about genetics is by performing DNA sequencing. This process reveals the order in which DNA's nucleotide protein bases appear in the DNA molecule. Initially, DNA sequencing was a slow process that has since been honed and developed to be rapidly and easily done given the proper equipment, knowledge and training.

Primer

• Before the DNA molecule can be sequenced, its individual chromosomes need to be broken down into smaller pieces, which are easier to analyze. The chromosomes have a base range of 50 million to 250 million, so breaking them down makes them easier to manage for the sequencing equipment. The smaller pieces are used to create sets of DNA fragments that differ in length, yet share the same DNA base.

Separation

• The smaller DNA fragments created during the priming step are separated using a process known as gel electrophoresis. Fluorescent dyes are added to the separated proteins to suppress the thermal conductivity of the molecules and to stop the molecules from passing other materials. In a simpler sense, this step essentially freezes the separated proteins in their place so that they can be analyzed in the next step of the DNA sequencing process.

Fragment Identification

• Each DNA fragment created in the previous two steps is identified by using the final protein base. This DNA base is recreated using the DNA sample's original sequence of A, T, C, and G proteins identified in each of the smaller DNA fragments. DNA sequencing equipment analyzes the results and then creates an output that illustrates each of the four different protein levels in the DNA molecule.

Protein Base Analysis

• Once the DNA sequences of each fragment are read, automated DNA sequencers assemble them together. Once they're rebuilt into a continuous stretch of DNA, the equipment analyzes them for errors and checks the genetic coding and structure. Finalized DNA sequences are then used in further research, to identify the source of the DNA and to compare to other genetic sequences that may share certain characteristics.