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DNA sequencing refers to the analysis the sequence of bases of specific DNA fragment, the arrangement of adenine (A), thymine (T), cytosine (C) and guanine (G). The emergence of rapid DNA sequencing method greatly promoted the research of biology and medicine.

In basic biology study, and in a wide range of applications, such as diagnostic, biotechnology, forensic biology and biological systematics, DNA sequences has become indispensable knowledge. With modern rapid speed of sequencing DNA technology have contributed to achieve complete sequencing of DNA sequence, or a variety of types of genome sequencing and life species, including the complete DNA sequences of the human genome, many other animals, plants and microbial species.

Sequencing principle

Chemical modification method of sequencing

Chemical reagents process end of DNA fragments, resulting in the bases of specific cutting, to produce a set of DNA chain reaction mixtures with different length, separated by gel electrophoresis. Chemical cutting reaction including the bases of decorate, modified bases from its sugar ringed out, after losing the bases of sugar rupture base in DNA.

The principle of sequencing using Sanger method

The principle is to use a DNA polymerase to extend the primers in undetermined sequence template, until it is mixed with a chain termination of nucleotides. Every sequencing is composed of a set of four separate reactions, every reaction with four DNA nucleotide triphosphate (dNTP), and mixed with limited different kind of double DNA nucleoside triphosphate (ddNTP). Due to the lack of 3 - OH groups ddNTP extension need, lengthen of the oligomeric nucleotide shall be selectively terminated in G, A, T/C. End point is determined by the kind of ddNTPs in the reaction. The relative concentrations of dNTPs and ddNTPs in the reaction can be adjusted to get a few hundred to a few thousand bases of product chain termination. They have a common starting point, but ended in different nucleotide, through resolution, can through resolution denatured gel electrophoresis separate different size pieces, after the gel treatment radiation from X-ray film developing avaliable or isotope labeling for testing.

Sequencing method

Generate independent groups with radioactive labeled oligonucleotide, the starting point of every set of oligonucleotide has fixed, but random ended in one or more specific residues. Because each bases of DNA in variable to terminate with the opportunity equality , so each set of products above are the mixture of oligonucleotide, the length of the oligonucleotide is decided by the location of a particular base on the original DNA fragment. Under the conditions of different DNA molecules with only a single nucleotide difference can distinguish between length to analysis by oligonucleotide electrophoresis, iust sample the groups of oligonucleotides in several adjacent sequencing gel lanes, the nucleotide sequence of DNA can be directly readed from the film of the gel.

The type of sequencing service

For conventional sequencing of unknown concentration of sample, you can choose this service.

Sample types including plasmid DNA, PCR products (purified PCR or no noise with PCR concentrate), bacteria (flat cloning or glycerin bacteria), phage has the ring of the genome (supernatant or plaque).

The advantages of DNA sequencing service

In order to meet your needs more, we also provide primer synthesis service, gene synthesis, protein expression and antibody customization services for you.