If the landlord refers to the human genome project, the method used at that time was called dideoxy termination method, also called Sanger method. The principle is that in the process of DNA synthesis, DNA polymerase can use ddNTP (dideoxynucleotide) as raw material, but its reaction will be terminated after adding ddNTP. The specific experiment is completed by PCR, but unlike ordinary PCR, it only needs one primer, not a pair. In four identical reaction systems, ordinary dNTP and four different ddNTP are added (for example, 1 system lacks dATP but has ddtp, and so on). Suppose ddtp, ddGTP, ddCTP and ddGTP are added to four systems, and we call these systems A, G, C and T respectively. Then in each system, the reaction will stop when it meets the corresponding base, thus producing a series of DNA fragments with different lengths ending in A, G, C and T respectively, such as the DNA fragment in system A, all ending in A. Then we take these fragments as a high ...

The earliest sequencing method is like this, but this method is extremely time-consuming. It needs to break DNA into countless suitable small fragments, sequence them and then put them together. This is also the reason why the human genome project needed the cooperation of so many countries and spent so much time.

Of course, modern second-generation DNA sequencing technology has become popular. Compared with the first generation DNA sequencing technology, they have the advantages of low cost, Qualcomm and short time consumption. If the second generation DNA sequencing technology is used to complete the human genome sequencing, it will take about a month at most now.