25
Dec
2009
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Glossary

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I

I
Isoleucine.
in-phase overlapping
The condition in which two or more proteins are translated in the same reading frame.
independent assortment (Mendel's second law)
The principle that in unlinked loci, the alleles of one locus segregate independently of the alleles of the other.
inferred tree
A phylogenetic tree based on empirical data pertaining to extant taxa.
informative site (diagnostic position)
A site that is used to choose the most-parsimonious tree from among all the possible phylogenetic trees. In molecular evolution, a site where there are at least two different kinds of nucleotides or amino acids, and each of them is represented in at least two sequences.
initiation codon
The first codon in the reading frame of a protein-coding gene; usually, ATG encoding methionine in eukaryotes and formylmethionine in prokaryotes.
insertion
A mutation in which one or more nucleotides are inserted into a DNA sequence.
insertion sequence
A transposable element carrying no genetic information except that which is necessary for transposition.
internal gene duplication (partial gene duplication)
Repeated sequences within a gene that have been derived from duplications involving less than the entire gene sequence.
internal node
The graphical representation of an ancestral organism or gene in a phylogenetic tree.
intron (intervening sequence)
A DNA segment of a transcribed gene, the transcript of which is removed in the process of RNA maturation and, therefore, does not appear in the mature RNA molecule. Resides between exons.
invariant repetition
The existence of repeated DNA segments that are identical or nearly identical in sequence to one another.
inversion
A mutation that causes a DNA segment to assume a reverse polarity.
isoaccepting tRNA
A tRNA molecule that recognizes more than one codon.
isochore
A genomic DNA segment that is homogeneous in base composition.
isozyme (isoenzyme)
Any of the distinct forms of an enzyme that have identical or nearly identical chemical properties but are encoded by different loci.
iterative alignment
A multiple sequence alignment technique wherein after a progressive alignment is completed, the initial sequence clusters are re-aligned to maximize the alignment score.
IUB
International Union of Biochemistry.
IUPAC
International Union of Pure and Applied Chemistry.