Sequencing of genome

Sequencing of genome :

        Genome sequencing is advancing in an accelerating speed generating hundreds of sequence information In the database everyday. more than 180 organisms have been sequenced so lit through different Individual arid integrated sequencing project  Most of these sequences are from prokaryotic. whose genome

are small and than if require less time to anoted  However long term scqucrwiiig prvecta collaborated at international levels led to sequencing of many I reukaryotini including mammals. In the animaI kingdom      gessequencing of Hawaii is a special landmark, which was conceptualized in 1983 and conipletrd in 2003 In the plant kingdom. sequence determination of rice plant isanodier landmark, as this crop feeds more than two It*d of the worldlier population. Sequencing the human geniwne has generatesi a huge database of genume information that has its devolution biological and biomedical silence by providing new iringhi into the life pesees. Genes responsible for deadly diseaas that were very difficult and laborious to identify in the         pregrncwnic era, are being identified, mapped and tested routinely using the sequence information generated through the genome sequencing proeces. With the genome sequence of other mammals moose

in hand. comparison of biochemical pathways and identification of new genes through comprehensiveness have become a reality. Such study helps in identifying fictional homologous in coding as well as non codin,g regions and suggests new roleicr the non coding genuine sequences that cossetitute the bulk of the grnome.

Common genes identified in mouse and human can he used to understand basic life procones le heain functioning or may be helpful to study drug response or oncogenic pathways. Sequences of closely related species may also be compared to reveal phlogenetlc relationships among related species. Recent sequencing of chimpanzee genome and ongoing sequencing pruccts on other primates are expected to provide information to solve the long debated ‘better last’ problem In human evolution. Gene based prediction of diseases. disorders and their remideal

    With the path breaking discovery of methods for sequencing a fragment of DNA, the science of genetics turned its attention from phenotype based identification and mapping of genes to identifying phenotype through knocking out a gene or predictive determination of gene function and phenotype effects through sequence determination. Sequencing by termination of DNA synthesis using dideoxy nucleo tide, a method developed by Fred Sanger has been extensive utilized in determination of nucleo tide sequences of a DNA fragment. A DNA to be sequenced in general is cloned in a vector like phage M13 to produce single

stranded DNA and then used for sequencing. With the advances in technological developments of sequencing strategies the chain termination method has been modified to make the procedure more robust, rapid and capable for sequencing longer DNA fragments. Many advanced automated genomic sequencing processes arc currently available that are routinely used in large scale genome sequencing projects. Use of fluorescence based detection methods in place of earlier radioactive detection procedure has helped to develop safer, rapid and easier ways to determine the sequence of a genome. In chapter 4, sequencing methods and their advancements have been discussed to provide an idea on genome sequencing.