NGS platforms perform massively parallel sequencing, during which millions of fragments of DNA from a single sample are sequenced altogether High-throughput sequencing (HTS). It processes thousands or millions of sequences concurrently
> 500,000 sequencing-by-synthesis operations run in parallel using state of the art sequencing methods in efficient ways Better call it High-Throughput Sequencing (HTS).
("Sequencing-by-synthesis means reading DNA by watching it being built, one glowing letter (base) at a time.")
NGS has revolutionized the modern biology by doing the sequencing of DNA and RNA in large amount, high speed and accuracy. Sanger Sequencing is known as the first generation sequencing which was used before because it was expensive, slow and sequence one DNA fragment at a time. In contrary NGS sequences millions of fragments in parallel, which makes it a powerful tool for large scale studies of genomics.
METHODOLOGY in brief:
Next-Generation Sequencing starts with the sample preparation (DNA or RNA). At first the genetic material is extracted from the organism (tissue, leaf etc), after extraction the nucleotide sequence is broken into small fragments. In the next step, adapters (short DNA sequences) are attached to the fragments, which creates a sequencung library. Then this library is loaded on the sequencing machine and the sequencing process takes place in the machine. We have different platforms in NGS, each has it’s own different chemistry but the main purpose is same and that is the reading of nucleotide sequence from each and every fragment.
TECHNOLOGIES IN NGS:
1. llumina (rev. terminator sequencing)
2. Roche’s 454 (pyrosequencing)
3. ThermoFisher Scientific (Ion Semiconductor sequencing)
4. Appled Biosystems (ABI) SOLiD sequencing
APPLICATIONS:
The applications of NGS are vast but some are listed below:
1. Whole-genome sequencing (WGS) : To look for variation in complete DNA sequence of an organism.
2. Whole-exome sequencing (WES) : To study protein-coding regions.
3. RNA sequencing (RNA-seq) : To look for gene expression , alternative splicing, and diversity in transcriptome.
4. It has an important role in cancer genetics, detection of pathogen, meta-genomics, agriculture, and personalized medicine.
ADVANTAGES:
1. It has ability to detect wide range of variations in genome for example INDELS.
2. Cost effective.
3. Fast.
4. Accurate.
5. Sequence millions of fragments at one time.
But the sequencing machines are expensive and proper bio informatics expertise is important and essential to analyze and interpret the data.
CONCLUSION:
In conclusion, NGS has revolutionized the way to explore genomes, finding variations and understand biological systems. The continuous advancements in NGS are improving discoveries in healthcare, agriculture, and molecular biology which makes it an essential tool in modern science.
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