DNA-Sequencer

DNA sequencing is the analysis of the nucleotide sequence - so-called bases sequence - in a DNA molecule.

Function principle of the sequencing

Basically, there are different processes for determining the sequence information of a DNA molecule. The probably best known process is the Sanger dideoxy method, also known as chain termination synthesis. dNTP is the abbreviation for a deoxynucleotide triphosphate and may replace therefore dATP, dCTP, dGTP or dTTP. ddNTP is, consequently, the corresponding dideoxy variation. For the Sanger sequencing method, the DNA double helix is first denatured by heating and then disassembled into its individual strands. Beginning with a primer, the so-called starting point, the DNA is extended by adding a deoxynucleotide or a dideoxynucleotide. Because the dideoxynucleotides are marked by the absence of the 3´-OH group, their integration causes a chain termination. Thus fragments of various lengths will be generated. Because each of four dideoxynucleotide units is marked with another fluorescence marker, the complete DNA sequence can be reconstructed by sorting the segments. The exact base sequence of a certain segment is achieved as a result.

Literature

• http://de.wikipedia.org/w/index.php?title=DNA-Sequenzierung&oldid=86737205 (called: 31.03.11).
• http://www.chemgapedia.de/vsengine/vlu/vsc/de/ch/5/bc/gentechnik/methoden.vlu/Page/vsc/de/ch/5/bc/gentechnik/methoden/dna_sequenzierung/dna_sequenzierung.vscml.html (called: 31.03.11).
• http://www.wellcome.ac.uk/Education-resources/Teaching-and-education/Animations/DNA/index.htm (called: 31.03.11).