Sequencing

==Polysaccharide sequencing==

==Polysaccharide sequencing==

Though [[polysaccharide]]s are also biopolymers, it is not so common to talk of 'sequencing' a polysaccharide, for several reasons. Although many polysaccharides are linear, many have branches. Many different units (individual [[monosaccharide]]s) can be used, and [[chemical bond|bonded]] in different ways. However, the main theoretical reason is that whereas the other polymers listed here are primarily generated in a 'template-dependent' manner by one processive enzyme, each individual join in a polysaccharide may be formed by a different [[enzyme]]. In many cases the assembly is not uniquely specified; depending on which enzyme acts, one of several different units may be incorporated. This can lead to a family of similar molecules being formed. This is particularly true for plant polysaccharides. Methods for the [[structure determination]] of [[oligosaccharide]]s and [[polysaccharide]]s include [[NMR]] spectroscopy and [[methylation analysis]].{{cite web| url = http://www.stenutz.eu/sop| title = A practical guide to structural analysis of carbohydrates}}

Though [[polysaccharide]]s are also biopolymers, it is not so common to talk of 'sequencing' a polysaccharide, for several reasons. Although many polysaccharides are linear, many have branches. Many different units (individual [[monosaccharide]]s) can be used, and [[chemical bond|bonded]] in different ways. However, the main theoretical reason is that whereas the other polymers listed here are primarily generated in a 'template-dependent' manner by one processive enzyme, each individual join in a polysaccharide may be formed by a different [[enzyme]]. In many cases the assembly is not uniquely specified; depending on which enzyme acts, one of several different units may be incorporated. This can lead to a family of similar molecules being formed. This is particularly true for plant polysaccharides. Methods for the [[structure determination]] of [[oligosaccharide]]s and [[polysaccharide]]s include [[NMR]] spectroscopy and [[methylation analysis]].{{cite web| url = http://www.stenutz.eu/sop| title = A practical guide to structural analysis of carbohydrates}}

==Draft and finished sequencing==

In draft sequencing, the order of base pairs in cloned genome fragments are usually determined at least four times (4× depth of coverage) at each position, a minimum threshold of accuracy.{{cite journal

| url = https://pmc.ncbi.nlm.nih.gov/articles/PMC1266063/

| author = Gardner SN; Lam MW; Smith JR; Torres CL; Slezak TR

| title = Draft versus finished sequence data for DNA and protein diagnostic signature development

| journal = Nucleic Acids Research

| date = 2005

| accessdate = 2026-05-01

| doi = 10.1093/nar/gki896

}} This information is assembled into [[contigs]]. A high-quality draft usually involves an 8× depth of coverage. Finished sequencing has no gaps or ambiguous [[Base calling|base calls]], with up to 10× coverage, as well as additional analyses, often manual, to orient the contigs against each other and to close the gaps between them in what is called finishing.

==See also==

==See also==