Editing Sequence analysis (section)

== Sequence assembly ==

Sequence assembly refers to the reconstruction of a DNA sequence by [[sequence alignment|aligning]] and merging small DNA  fragments. It is an integral part of modern [[DNA sequencing]]. Since presently-available DNA sequencing technologies are ill-suited for reading long sequences, large pieces of DNA (such as genomes) are often sequenced by (1) cutting the DNA into small pieces, (2) reading the small fragments, and (3) reconstituting the original DNA by merging the information on various fragments.

Recently, sequencing multiple species at one time is one of the top research objectives. Metagenomics is the study of microbial communities directly obtained from the environment. Different from cultured microorganisms from the lab, the wild sample usually contains dozens, sometimes even thousands of types of microorganisms from their original habitats.<ref>{{cite journal|last1=Wooley|first1=JC|last2=Godzik|first2=A|last3=Friedberg|first3=I|title=A primer on metagenomics|journal=PLOS Comput Biol|date=Feb 26, 2010|volume=6|issue=2|doi=10.1371/journal.pcbi.1000667|pmid=20195499|pmc=2829047|pages=e1000667|bibcode=2010PLSCB...6E0667W |doi-access=free }}</ref> Recovering the original genomes can prove to be very challenging.