# Different DNA Sequencing Using DNA Graphs: A Study
## 1 Introduction  
DNA is a molecule that transfers genetic info to all living creatures. It is composed of two long polynucleotide chains that are bonded together to form a double helix structure. Each of these chains has a backbone made of a five-carbon sugar known as deoxyribose, which is attached to phosphate groups and a nitrogen-containing base. The nitrogenous base might be either adenine (A), thymine (T), guanine (G), or cytosine (C). A always pairs with T, and G with C. Genomic DNA has a significant role in the determination of individuals and species in most cases, making DNA sequence study important for understanding cell structures and activities and unlocking biological mysteries [1]. DNA sequencing technology might be useful for biologists and health care practitioners for various applications, including molecular cloning, breeding, diagnosing diseases and genetic disorders, and comparative and evolutionary research. Therefore, DNA sequencing technology should ideally be quick, accurate, simple to use, and inexpensive. DNA sequencing methods and applications have advanced tremendously in the last thirty years, and they now serve as an engine for genome age, which is defined by large amounts of genomic data. As a result, there is a diverse variety of study topics and applications. Studying the history of sequencing technology development is very important for evaluating next-generation sequencing systems (NGS), such as pyrosequencing (454), genome analyzer and high-throughput sequencing, and SOLiD sequencing. In addition, it helps for comparing the advantages and disadvantages of the technology and explaining the variety of applications. Moreover, the importance of the history of sequencing development also lies in the ability to evaluate the personal genome machines (PGM) and third-generation technologies and their applications. The majority of the information and conclusions come from independent users with considerable first-hand experience with BCI's (the Beijing Genomics Institute's) standard NGS equipment. Prior to entering into NGS systems, let us take a look at the brief history of DNA sequencing. [PERSON] invented DNA sequencing in 1977 using the chain-termination approach (often referred to as Sanger sequencing). In contrast, [PERSON] developed another method in 1978 using a DNA chemical modification and subsequent cleavage at certain bases. Due to its low radioactive nature and great efficiency, Sanger sequencing was selected as the dominant approach in the \"first generation\" of commercial and laboratory sequencing applications [2]. DNA sequencing was time intensive and required the use of radioactive materials at the time [3]. In 1987, Applied Biosystems introduced the world's first automated sequencing machine (the AB370), which accelerated and improved sequencing accuracy via the use of capillary electrophoresis. The AB370 was competent in concurrently detecting 96 bases at a 500 K basis rate every day and 600 bases per reading. Since 1995, the latest model, AB3730 xl, has been able to generate 2.88 million bases per day and read lengths of up to 900 bases. Automatic sequencing devices and Sanger sequencing technology and related software based on capillary sequencing machines, which first appeared in 1998, became the primary instrument for completing the \"Human Genome Project\" [HGP] in the year 2001 [4]. This effort aided in the creation of a powerful new sequencing apparatus that was able to increase accuracy and speed while lowering costs and decreasing labor. Not only that, but the X-prize has strengthened next-generation sequencing (NGS) technology [5]. In terms of lower cost, massively parallel analysis, and high throughput, NGS technologies differ from the Sanger approach. Despite the fact that NGS makes genome sequences more accessible, the biological explanations and subsequent data analysis remain a bottleneck in comprehending genomes. Recently, [PERSON] and [PERSON] [6] discussed the topic of formalizing graph data models for genomic information representation.