DNAsekvensointimenetelmä

DNAsekvensointimenetelmä refers to the process of determining the precise order of nucleotides within a DNA molecule. This order, known as the DNA sequence, contains the genetic instructions for the development, functioning, growth, and reproduction of all known organisms. Understanding DNA sequences is fundamental to many areas of biology and medicine.

Historically, the first widely used method was the Sanger sequencing method, developed by Frederick Sanger in the 1970s. This technique, also known as the chain-termination method, relies on dideoxynucleotides, which cause DNA synthesis to terminate at specific bases. By running these terminated fragments on a gel electrophoresis, the sequence can be read. While highly accurate for specific DNA fragments, Sanger sequencing is relatively slow and expensive for large-scale projects.

With the advent of the Human Genome Project, the need for faster and more cost-effective sequencing technologies grew. This led to the development of next-generation sequencing (NGS) technologies. NGS platforms, such as Illumina sequencing, involve massively parallel sequencing, allowing millions of DNA fragments to be sequenced simultaneously. These methods often use a sequencing-by-synthesis approach, where fluorescently labeled nucleotides are incorporated into growing DNA strands, and the emitted light signals are detected to determine the base at each position. NGS has dramatically reduced the cost and increased the speed of DNA sequencing, enabling applications like whole-genome sequencing, exome sequencing, and transcriptomics.

More recently, third-generation sequencing technologies, such as PacBio and Oxford Nanopore sequencing, have emerged. These methods can sequence much longer DNA fragments, often entire genes or even chromosomes, in a single read. This capability is particularly useful for resolving complex genomic regions and identifying structural variations. The continuous development of DNA sequencing methods continues to expand our understanding of genetics and drive innovation in various scientific fields.