Library (biology)

In molecular biology, a library is a collection of molecules in a stable form that represents some aspect of an organism. Two common types of libraries are complementary DNA (cDNA) libraries and genomic libraries. The nucleotide sequences of interest are preserved as inserts to a plasmid. A cDNA library represents all of the mRNA present in a particular tissue, while a genomic library represents all of the DNA sequences found in the genome, broken into fragments of a manageable size.

Related Topics:
Molecular biology - Complementary DNA - Genomic - Plasmid - MRNA

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It seems more than reasonable to add to this the ?combinatorial library,? a molecular ensemble of variations on a template molecule. Examples of combinatorial libraries would be, for example, the collection of peptide octamers with defined residues of which only one is variable (20 members,) that same collection, now with two variable residues (20^2 members,) all possible octamers (20 to the power 20 members) or the product of a PCR reaction where fidelity was not 100 percent.

Related Topics:
Combinatorial - Molecular - Template - Molecule - Peptide - Octamer - Residue - Variable - Collection - Product - PCR - Reaction - Fidelity

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Please note that the product of normal PCR reactions is not generally called a library, since mutations are so very rare. (There are myriad techniques, though, that purposely and efficiently reduce fidelity.)

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