B	B	In proteins, it indicates that the amino acid could be either Aspartic Acid or Glutamic Acid. Sometimes you can't tell because of the amide could be hydrolyzed during purification.
	backtracking algorithm	The process of repeatedly exploring paths until you encounter the solution. Also called recursion.
	bacteria	Structurally simple, single celled organism, with no nucleus.
	bacteriophage	Phage - a virus that infects a bacterium.
	BAC	Bacterial artificial chromosome. A circular piece of DNA that can exist and replicate within a bacteria. BACs are often used to clone human DNA.
	balanced polymorphism	A polymorphism that is stable over time and is maintained by balancing selection.
	balanced selection	A selection regime that results in the maintenance of two or more alleles at a locus in a population (e.g. overdominance).
	banding	Areas of light and dark staining on chromosomes.
	basal promoter	The position within a eukaryotic promoter where the initiation complex is assembled.
	basal rate of transcription	The number of productive initiations of transcription occurring per unit time at a particular promoter.
	base	One of the building blocks of DNA or RNA. The four bases in DNA are adenine (a), cytosine(C), guanine(G), and thymine(T). Uracil (U) is used in place of thymine(T) in RNA.
	base analog	A compound whose structural similarity to one of the bases in DNA enables it to act as a mutagen.
	base excision repair	a DNA repair process that involves excision and replacement of an abnormal base.
	baseless site	A position in the DNA molecule where the base component of the nucleotide is missing.
	base pair (bp)	Two bases (adenine and tymine, or guanine and cytosine) held together by weak hydrogen bonds. The two strands of DNA are held together in the shape of a double helix by the bonds between the base pairs. A "bp" is considered a unit of measurement of double-stranded DNA length.
	base sequence	The order of nucleotide bases in a DNA or RNA molecule.
	base sequence analysis	A method, sometimes automated, for determining the base sequence of DNA or RNA.
	base stacking	The hydrophobic interactions that occur between adjacent base pairs in a double-stranded DNA molecule.
	basic domain	A type of DNA binding domain.
	bash	A UNIX shell.
	batch Entrez	A feature in Entrez that allows the retrieval of many sequences at once and saves the sequences to a file on a local computer. This is particularly useful if you want to download a set of sequences to analyze locally.
	Bayes Theory	A statistical theory which allows you to integrate the current experimental data with what you knew before the experiment.
	B-DNA	The most common structural conformation of the DNA double helix in living cells.
	beta sheet	A common secondary structure of a protein where several beta strand (or elongated) regions of a protein line up next to each other to form a flat sheet structure (Monellin 1MON).
	beta turn	A sequence of four amino acids, the second is usually glycine, which causes a polypeptide to change direction.
	bifurcation	The graphical representation in a phylogenetic tree of an evolutionary speciation event whereby an ancestral taxon splits into two.
	biochemical pathway	A network of interacting molecules that is responsible for a specific biochemical junction, such as a metabolic pathway or a signal transduction pathway.
	bioinformatics	Refers to the wide range of computational techniques used to analyze DNA and protein sequences.
	biological information	The information contained in the genome of an organism and which directs the development and maintenance of that organism.
	biotechnology	A set of biological techniques developed through basic research, and now applied to research and product development. In particular, the use by industry of recombinant DNA, cell fusion, and new bioprocessing techniques.
	bit	A single unit of computer memory. It has two states, 0 or 1.
	bit score	A scaled version of an alignment's raw score that accounts for the statistical properties of the scoring system used.
	BLAST	Basic Local Alignment Search Tool. A heuristic sequence comparison algorithm, that is used to search sequence databases for optimal local alignments to a query.
	blunt end	An end of a double-stranded DNA molecule where both strands terminate at the same nucleotide position with no single-stranded extension.
	blunt end ligation	Linking together of two double stranded DNA molecules which have blunt ends.
	bootstrapping	A statistical method that is often used to estimate the reproducibility of specific features of phylogenetic trees.
	bottleneck	A severe reduction in population size.
	box	A short DNA sequence adjacent to or residing within a gene that performs a regulatory function (e.g., TATA box)
	bp	Base pair.
	branch	The graphical representation of an evolutionary relationship in a phylogenetic tree.
	branch migration	A step in the Hollliday model for homologous recombination involving exchange of polynucleotides between a pair of recombining double-stranded DNA molecules.
	browser	A program used to access sites on the World Wide Web.
	B-Tree	Balanced Tree. A common data structure for creating indexes on disk.
	byte	An amount of computer memory that holds a single character. It is usually 8 bits in length.