The Human Genome Project was declared complete in 2003. The entire genome of an organism consists of only four deoxyribonucleotide bases – A, T, G and C.
Determining the sequence of the four rather simple molecules within approximately 3 billion base pairs was quite a challenging task for the team of brilliant researchers determined to sequence all the genes within the human genome.
DNA sequence analysis can involve multiple steps that include the alignment of DNA sequences, and searches against established databases.
Sequence analysis can provide the research team with an understanding of the function of different genes, their interactions with protein, structures, and evolution.
Comparison of the new sequences with the already stored DNA sequence data allows researchers to explore the similarity between the genetic makeup of organisms and their differences.
In molecular biology, DNA sequence analysis is instrumental in the:
i. Comparison of different DNA sequences to find the similarities and relationship between them (identification of homologs).
ii. Documentation of differences between comparable sequences to determine single nucleotide polymorphism (SNP) and genetic markers.
iii. Determination of active sites, sites of post-translational modifications, reading frames, intron and exon distributions, regulatory elements of a gene, and other intrinsic features.
iv. Studying the evolution and genetic diversity in organisms (prokaryotes and eukaryotes).
v. Identification of the structure of macromolecules from the complete sequence analysis.
vi. Creation of phylogenetic trees using DNA sequences from multiple organisms.
vii. Determination of DNA sequences from unknown or previously uncharacterized microorganisms within their natural habitat.
The first step in the analysis of DNA: first-generation DNA sequencing
The first generation of DNA sequencing allowed the team to sequence the entire genome. While using Sanger sequencing, researchers typically sequenced DNA molecules of up to 900 base pairs routinely.
The analysis of the resulting DNA containing the labeled ddNTP from the Sanger sequencing involves the use of a gel matrix called the capillary gel electrophoresis.
The original DNA sequence can be reconstructed from the different dye-labeled molecules registered by the sensor, one after the other. The final data shows a series of peaks of fluorescence intensity.
Next-generation sequencing: faster and cheaper DNA seq analysis
Large genome sequencing projects that require a quick turnaround demand a method that is faster than Sanger sequencing.
When the question of sequencing entire genomes and metagenomes of organisms arise, the only viable answer is Next Generation Sequencing (NGS) ricepurity.
NGS has several applications in biotechnology, molecular biology, biomedicines, microbiology, oncology, and genetics…
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