3. CONTENT
Introduction
History of DNA sequencing
Types of sequencing
Next Generation Sequencing(NGS)
Types of NGS instrument
Application of NGS
Future challenges
Conclusion
Reference
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4. INTRODUCTION
DNA Sequencing: Process of determining
the precise order of nucleotide within
a DNA molecule
It includes any method or technology that
is used to determine the order of four bases-
Adenine
Guanine
Cytosine
Thymine
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9. NEXT GENERATION SEQUENCING
Tradition (Sanger) sequencing generates a small number
of intermediate length reads(~1000 bp)
All NGS technologies perform millions of parallel sequencing
reactions to many,typically short,reads per run
High-throughput sequencing
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10. 10
Next Generation Sequencing: Why
Now?
• Motivation: HGP and its derivatives, personalized medicine
• Short reads applications: (re-)sequencing, other methods (e.g. gene expression)
• Advancements in technology
14. ABI’s SOLiD
• Probably the second most widely used
• The workflow is similar to Solexa/Illumina’s
• An intensity difference: SoLiD uses a di-base
sequencing technique in which two nucleotide
are read simultaneously,16 di-base still repeated
by 4 “colors” but the one base shift the redundancy
• As a consequence:
- Sequencing error may propagate
- Read alignment can be speed up
• Error rate around 2-4%
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19. APPLICATION OF NGS
Molecular biology
Evolutionary biology
Metagenomics
Medicine
Forensics
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20. FUTURE CHALLENGES
Defining variability in many human beings
DNA sequencing currently under development
include reading the sequencing as a DNA strands
transits through nanopores
Third generation technologies aim to increase
throughput and decrease the time to result and cost
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21. CONCLUSION
The sequence based characterization of genome is a relatively
young pursuit in biological science, enhanced model
organism and human genetics
Ability to gather genome-wide sequence information more rapidly
that can inform a higher level appreciation of functional genome
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NGS is a general term refering to all post-Sanger sequencing technologies that enable massive sequencing at low cost.
NGS may be further divided into polony-sequencing based technologies which require the amplification of DNA prior to sequencing, and single molecule sequencing which do not.
Motivation for new technologies drives its roots not only from potentially commercial usage such as in personalised medicine, but also from government supported projects suce as the HGP or the 1000 genomes projects aiming to sequence the genomes of 1000 individuals around the world with price tag for genome sequencing single genomes set to 50,000$.
other than de-novo sequencing Potential applications include re-sequencing, and also gene expression analysis, both can make use of short reads which are offered by all current technologies. So despite the read-length barrier of the new technologies, sequencers still became commercial.
And of course – advancements in chemistry, microscopy and other related technologies enabled the new sequencing technologies.
