Platforms

Introduction Since the discovery of the DNA molecule by James Watson and Francis Crick in 1953, the field of molecular biology and genomics has escalated substantially especially in the last decade as a result of the completion of the Human Genome Project.^1,2 In 1990, the National Institutes of Health (NIH) and the Department of Energy (DOE) formulated and published a 5 year plan to begin sequencing the entire human genome.¹ This international undertaking which was estimated to last 15 years was completed a head of schedule in 2003 due to advances in deoxyribonucleic acid (DNA) sequencing techniques.^3,4

DNA is a double helical structure that contains the sugar deoxyribose (a five carbon sugar which lacks an oxygen at the 2′ position hence the term “deoxy”); a phosphate group; and four deoxynucleotide triphosphates (dNTPs): deoxyadenosine triphosphate (dATP), deoxycytidine triphosphate (dCTP), deoxyguanosine triphosphate (dGTP) and deoxythymidine triphosphate (dTTP).^5,6 The sugar phosphate backbone when covalently linked to a nucleoside is referred to as a nucleotide.⁶ Due to the chemical composition of the dNTPs, adenine always binds to thymine while cytosine always binds to guanine. DNA contains the genetic code necessary for an organism to reproduce and survive and can generate an exact copy of itself through the process known as DNA synthesis.

DNA synthesis requires the following components: DNA template; DNA primer; DNA polymerase which adds the nucleotides to the growing chain; four deoxynucleoside triphosphates: dATP, dTTP, dCTP and dGTP; and an energy source adenosine triphosphate (ATP) to catalyze the reaction.^5,7 During the elongation…

ABBREVIATIONS: ATP - adenosine triphosphate; dATP - deoxyadenosine triphosphate; dCTP - deoxycytidine triphosphate; ddNTP - dideoxynucleotide triphosphate; dGTP - deoxyguanosine triphosphate; DNA - deoxyribonucleic acid; dNTP - deoxynucleotide triphosphate; DOE - Department of Energy; dTTP - deoxythymidine triphosphate; emPCR - emulsion Polymerase Chain Reaction; GS - genome sequencer; ISPs - Ion sphere particles; NGS – next generation sequencing; NIH - National Institutes of Health; OH - hydroxyl; PCR - Polymerase Chain Reaction; PGM - Personal Genome Machine; ³²P - Phosphorous 32 (isotope); SMRT - single molecule real time; ZMW - zero mode waveguides.