From Wikipedia,
the free encyclopedia.
A gene family is a set
of
genes defined by presumed
homology, i.e. evidence that
the genes evolved from a common
ancestral gene. They generally
share some
biochemical activity. Genes
are generally categorized into
families based upon shared
sequence motifs and similarities
in structure.
Phylogenetic techniques can be
used as a more rigorous test. The
positions of
introns within the coding
sequence can be used to infer
common ancestry. Knowing the
sequence of the
protein encoded by a gene can
allow researchers to apply methods
that find similarities among
protein sequences that provide
more information than similarities
or differences among DNA
sequences. Furthermore, knowledge
of the protein's secondary
structure gives further
information about ancestry, since
the organization of secondary
structural elements presumably
would be conserved even if the
amino acid sequence changes
considerably. These methods often
rely upon predictions based upon
the DNA sequence.
If the genes of a gene family
encode proteins, the term
protein family is often used
in an analogous manner to gene
family.
See also:
List of gene families,
phylogenetic tree
