Sequencing

Of Biochemistry, the sequencing consists in determining the linear order of the components of a Macromolécule (amino-acid of a Protéine, the Nucléotide S of a Nucleic acid like DNA, the Monosaccharide S of a Polysaccharide, etc).

In Genetic, the sequencing even relates to the determination of the sequence of the Gènes of the Chromosomes, even of the complete Génome. What technically amounts carrying out the sequencing of the DNA constituting these genes or these chromosomes.

Sequencing of the DNA

See also: Sequencing of the DNA

The sequencing of DNA, consists in determining the order of sequence of nucleotides of a fragment of DNA given. Currently, the majority of the sequencing of DNA are carried out by the method of Sanger. This technique uses the reaction of polymerization of the DNA with an enzyme (in the past the fragment of Klenow) " the sequenase" synthesized completely artificially and of the didésoxyribonucléotides (ddNTP).

The sequence of DNA contains the necessary information with the living beings to survive and reproduce. To determine this sequence is thus useful as well for research aiming at knowing how the organizations as for subjects applied live. In medicine, it can be used to identify, diagnose and potentially find treatments genetic diseases. Biotechnology is a prosperous discipline with prospects for many products and useful services.

Method of Sanger

In the method of Sanger, the polymerization of DNA is initiated by small a oligonucléotide (starts) complementary to part of the fragment of DNA with séquencer. The elongation of the starter is carried out by the “séquénase” (a DNA polymerase I deprived of exonucleasic activities 5' →3' and 3 ' →5', and 100 times faster than the fragment of Klenow). The four désoxynucléotides (dATP, dCTP, dGTP, dTTP) are added, like in weak concentration the four 2 ' - 3 ' didésoxynucléotides (ddATP, ddCTP, ddGTP, ddTTP) marked by different fluorochromes. These didésoxynucléotides, once incorporated in the new synthesized chain, prevents the continuation of the elongation. It results from it from new fragments of variable DNA of size, which are then separated by electrophoresis on a gel from Polyacrylamide.

to see too

biological Sequence

Sequencing of the genome

  • Sequencer of genes
  • Project human genome
  • List of the genomes sequences

Sequencing of proteins

to also see: Sequencing of the proteins

Sequencing of polysaccharides

To supplement….

External bonds

  • Questions in connection with the sequencing of the human genome
  • Publications of the sequencing of the human genome

Sources

  • - Bio-data processing: Appendix {{{2}}} (version filed) (the Infobiogen resource center ceased its in June 2006 activities)

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