DNA sequencing refers to determining the exact order of nucleotides (Adenine, Thiamine, Guanine, Cytosine) for the DNA in a cell. The major scientific advancement that occurred in this area was the completion of the Human Genome Project in 2003. The aim of this project was to sequence the entire DNA in a human cell and to determine which sections of DNA represent individual genes (protein-coding units).

DNA samples were collected from all over the world

and sent to the Human Genome centres where scientists performed DNA sequencing and analysis. Therefore the full sequence was published and researchers determined that within this sequence there was somewhere between 30,000 and 40,000 genes.

Some scientists still argue that the complete sequencing of the human genome is not complete because current technology has left many bases of repeat-rich heterochromatin and several small gaps unfinished. However, they seem to agree that the confirmed number of genes in the human is closer to 25,000.

Scientists are currently using this information to work on projects that compare genomes between human beings and other animals while other projects are investigating interactions between DNA sequences, gene products and environmental factors and analysing genetic variations between individuals in a population. An online system known as ENCODE (Encyclopaedia of DNA Elements) has also been invented that enables the scientific and medical communities to interpret the human genome sequence and apply it to understand human biology and improve health. In addition to the variation information catalogued by the International HapMap in 2007 and 100 Genomes project in 2012, researchers have built a reliable foundation for genetic research routed in the human genome sequence. The first genome-wide ENCODE papers were published in 2012 to help everyone in and outside the scientific community understand the meaning of these sequences.

Archiving of a lot of information on sequencing is operating under the International Nucleotide Sequence Database Collaboration (INSDC) which is currently preserving all sequences equally but it has been indicated that the rapid increase in the rate of global sequence production will soon lead to differentiated treatment of DNA sequences being submitted. This will be a major advancement in the storage and maintenance of the records. It will also contribute to easy retrieval of these sequences for different scientific purposes. Rapid advancement in sequencing technology, commonly referred to as the next generation sequencing, has contributed towards analyzing large numbers of DNA thus delivering large volumes of data over a short period of time. Sanger sequencing method which has been used for several years is no longer the only technique that can be applied for analysis of DNA.

Over the past several decades technical advances automated and refined the Sanger sequencing method. The new technologies that have been developed to further increase the efficiency of sequencing include flow cytometry, scanning microscopes, mass spectrophotometer and hybridization strategies. Next generation sequencing has been seen to be a major contributor towards

advancement of DNA sequencing and molecular biology as a whole

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February 9th, 2014

Posted In: DNA sequencing

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