I	I	Isoleucine in proteins
	identity diagonal	In an intrasequence dot matrix comparision, the identity diagonal represents the one-to-one matching of the sequence with itself.
	identity matrix	A scoring system in which only identical characters recieved a positive similarity score.
	idiopathic	arising spontaneously or from an obscure or unknown cause
	idiotype	Antigenic determinants that distinguish one variable domain from other variable domains.
	immunoscreening	The use of an antibody probe to detect a polypeptide synthesized by a cloned gene
	incomplete dominance	Refers to a pair of alleles, neither of which displays dominance, the phenotype of a heterozygote being intermediate between the phenotypes of the two homozygotes.
	indel	A position in an alignment between two DNA sequences where an insertion or deletion has occured
	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.
	index	A data structure that helps us find data items quickly given a part of their value.
	inducer	A molecule that induces expression of a gene or operon by binding to a repressor protein and preventing the repressor from attaching to the operator.
	inelastic scattering	Compton scattering. In X-ray crystallography, when the X-ray photon is deflected from its original direction with or without loss of energy
	inferred tree	A phylogenetic tree based on empirical data pertaining to extant taxa.
	informatics	The study of the application of computer and statistical techniques to the management of information. In genome projects, informatiocs includes the development of methods to search databases quickly, to analyze DNA sequence information, and to predict protein sequence and structure from DNA sequence data.
	information content	The number of bits needed to uniquely specifiy a message, where one bit is able to distinguish between two eaually likely things. When the base frequencies are equal, it takes one bit to distinguish a purine from a pyrimidine, and two bits of information to uniquely specifiy a single base.
	inhibitor-resistant mutant	A mutant that is able to resist the toxic effects of an antibiotic or other type of inhibitor.
	initiation codon	The codon, usually but not exclusively 5'-AUG-3', found at the start of the coding region of a gene.
	initiation codon	The codon, usually but not exclusively 5'-AUG-3', found at the start of the coding region of a gene.
	initiation codon	The codon, usually but not exclusively 5'-AUG-3', found at the start of the coding region of a gene.
	Initiation complex	The complex of proteins that initiates transcription. Also, the complex that initiations translation.
	Initiation factor	A protein that plays an ancillary role furing initiation of translation.
	Initiation of transcription	The assembly upstream of a gene o fthe complex of proteins that will subsequently copy the gene into RNA
	Initiation region	A region of eukaryotic chromosomal DNA within wihch replication initiates at positions that are not clearly defined
	Initiator sequence	A component of the RNA polymerase II core promoter.
	Initiator tRNA	The tRNA, aminoacylated with methionine in eukaryotes or N-formylmethionine in bacteria, that recognizes the initiation codon during protein synthesis.
	inode	In the UNIX operating system, the internal representation of a file is given by an inode, which contains a description of the disk layout of the file data and other information such as the file owner, access permissions, and access time. Every file has one inode. A contraction of the term index node.
	Inosine	A modified versoin of guanosine, sometimes found at the wobble positon of an anticodon.
	in-phase overlapping	The condition in which two or more proteins are translate din the same reading frame.
	Insertional editing	A less extensive form of pan-editing that occurs during processing of some viral RNAs.
	Insertion mutation	A mutation that arises by insertion of one or more nucleotides into a DNA sequence.
	Insertion sequence	A short transposable element found in bacteria
	integer	a whole number. A number without fractional parts
	Integrase	A Type I topoisomerase that catalyzes insertion of the lambda genome into Eschericia coli DNA.
	Intein	An internal ssegment of a polypeptide that is removed by a splicing process after translation.
	Intein homing	The conversion of a gene coding for a protein that lacks an intein into one coding for an entein-plus protein, catalyzed by the spliced component of the intein.
	intercalating agent	A compound that can enter the space between adjacent base pairs of a double-stranded DNA molecule, often causing mutations. Usually flat aromatic molecules like acridine or ethidium bromide.
	internal gene duplication	Repeated sequences within a gene that have been derived from duplications involving less than the entire gene sequence.
	internal node	A branchpoint with a phylogenetic tree, representing an organism or DNA sequence that is ancestral to those being studied.
	Internet	A system of linked computer entworks used for the transmission of files and messages between hosts
	interphase	The period between cell divisions
	Intranet	A computer network internal to a company or organization. Intranets are often not connected to the Internet or are protected by a firewall.
	intrinsic terminator	A positon in bacterial DNA where termination of transcription occurs without the involvement of Rho.
	intron	A noncoding region within a discontinuous gene.
	intron homing	Teh conversion of a gene lacking an intron into one that contains an intron, catalyzed by a protein coded by that intron.
	introns early	The hypothesis that introns evolved relatively early and are gradually being lost from eukaryotic genomes
	introns late	The hypothesis that introns evolved relatively late and are gradually accumulating in eukaryotic genomes.
	invariant repitition	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.
	Inverted repeat	Two identical nucleotide sequences repeated in opposite orientations in a DNA molecule.
	in vitro	A process that takes place in an isolated cell-free extract.Also refers to cells growing in culture.
	in vitro mutagenesis	Techniques used to produce a specified mutation at a predetermined position in a DNA molecule.
	in vivo	In an intact cell or organism
	IP Address	The unique, numeric address of a computer host on the Internet.
	isoaccepting tRNAs	Two or more tRNAs that are charged with the same amino acid.
	isochore	A genomic DNA segment that is homogeneous in base composition.
	isoelectic point	The pH at which a molecule has no net electrical charge and therefore does not move in an electric field.
	isoforms	Multiple forms of the same protein that differ in their amino acid sequence. Produced by different genes or alternative splicing of mRNA.
	isomorphous	Different crystals that have identical unit cell lengths and angles and are in teh same space group.
	isomorphous replacement	the attachment of heavy atoms to the protein molecule in a crystal without changing the shape of the protein. Used as a method in X-ray crystallography to find the phase angle.
	isoprene	Small unsaturated hydrocarbon containing five carbon atoms. The basic building block of many natural organic molecules including terpenes, retinoic acid and steroids.
	isotope	One or two or more atoms that have the same atomic number but different atomic weights.
	isotropic temperature factor	The temperature factor is a consequence of the dynamic disorder in the crystal caused by the temperature-dependent vibration of the atoms in the structure.
	isotype	Antigenic determinants that distinguish the constant regions of the different heavy-chain classes and light-chain types. Each isotype is encoded by a distinct gene and most likely arose by gene duplication and divergence.
	isozyme	Any of the distinct forms of an enzyme that have identical or nearly identical chemical properties, but are encoded by different loci.
	iterative search	After performing an initial search against the database, the high scoring matches are used to search the database again. In some cases (intermediate sequence path), these sequences are used on their own; in others, the sequences are joined together in an alignment or profile.