Module name and number
Molecular Biology & Genetic Engineering: BS941
“DNA sequencing: where we are and where it’s going”
The article focuses on the advances achieved in DNA sequencing by first providing a brief background on DNA, and how it was initially sequenced. The paper then takes into consideration four of the major DNA sequencing techniques. These include: Sanger’s Chain Termination Method, Pyrosequencing, Single Molecule Real-Time Sequencing and Nanopore Technology. Finally, recent and future applications of DNA sequencing will be addressed.
Deoxyribonucleic acid (DNA) is a self-replicating molecule present in all living organisms. It harbours the heritable genetic information necessary for organisms to grow, live and reproduce (Craig et al., 2010; Oxford dictionary 2014). DNA is characterized by two polynucleotide strands arranged into a double helix, consisting of alternating sugar deoxyribose and phosphate, which are joint by hydrogen bonds between the complementary nucleotide bases: adenine (A); thymine (T); guanine (G); cytosine (C) (AHSD, 2005). After the discovery of DNA structure by James Watson and Francis Crick, it became possible to determine the precise order of the nucleotide bases via a process known as DNA sequencing (Twyman, 2014; Watson and Crick 1953). However, sequencing was first performed on bacteriophage MS2 ribonucleic acid (RNA), which encoded the viral coat protein (Jou et al., 1972). Subsequently, Padmanabhan et al., (1974) were able to obtain the DNA sequence of the gene coding for T4 bacteriophage lysozyme thanks to primer extension method, which was then used by Fredrick Sanger to sequence the genome of bacteriophage φX174, 5375 nucleotides long (Sanger et al., 1977). With the advances in sequencing technology, such as the application of gel electrophoresis and fluorescent