D Aspartic acid in proteins D Arm part of the structure of a tRNA molecule Darwinian fitness fitness data information manipulated by a program data structure The heirarchy of types in a program. data type a description of a variable defined by two properties In C, you have four main types. Integer, floating point,
boolean and text. but you can define others. data warehouse A database containing data that is often accessed, but
seldom changed. deaminating agent A mutagen that acts by removing amino groups from
nucleotide bases decoding translation deductive database A database that contains both facts (often in the form of
a relational database) and rules for reasoning (often in
logic programming) so that new facts can be dynamically
generated from stored facts. degenerate code A genetic code in which the number of sense codons is
larger than the total number of amino acids and, some amino
acids are specified by more than one codon. All known
genetic codes are degenerate. deletion mutation A mutation resulting from deletion of one or more
nucleotides from a DNA sequence deleterious mutation A mutaton that lowers the fitness of its carriers. denaturation Breakdown by chemical or physical measn of the
noncovalent interactions such as hydrogen bonding, that
maintain the secondary and highter levels of structure of
proteins and nucleic acids. The loss of a protein's tertiary
structure. Sometimes used as a synonym for DNA melting de novo methylation Addition of methyl groups to new positions on a DNA
molecule Depth first search A common recursive algorightm used to explore a graph. To
search a tree, the search first vists the root of the tree,
and then successively explores each branch. deoxyribonuclease An enxyme that cleaves phophodiester bonds in a DNA
molecule. derived character state A character state that evolved in a recent ancestor of a
subset of organisms in a group being studied. descriptor Information about a sequence or set of sequences whose
scope depends on its placement in a record. A descriptor is
placed on a set of sequeces to reduce the need to save
multiple redundant copies of information. deterministic process A process, the outcome of which can be predicted exactly
from knowledge of initial conditions development A coordinated series of transient and permanent changes
that occurs during the life history of a cell or
organism. diagonal In a dot matrix comparison, a row of dots along a
diagonal which represents a region of high local similarity
between two sequences. dichotomy bifurcation diff UNIX program for comparing two files differentiation The adoption by a cell of a specialized biochemical
and/or physiological role digestion The cutting of a double-stranded DNA by a restriction
endonuclease dimer A protein or other structure that comprises two
subunits diploid A nucleus that has two copies of each chromosome directed evolution A set of experimental techniques that is used to obtain
novel genes with improved results. directed shotgun approach A genome-sequencing strategy which combines random
shotgun sequencing with a genome map, the latter used to aid
assembly of the master sequence. Direct readout the recognition of a DNA sequence by a binding protein
that mkes contacts with the outside fo a double helix. Direct repeat A nucleotide sequence that is repeated twice or more
frequtntly ina DNA molecule directional selection A selective regime that changes the frequency of an
allele in a specific direction, either toward fixation or
toward elimination disjunction The separation of homologous chromosomes during meiosis
or the separation of complementary chromatids during
mitosis distance genetic distance distance matrix A matrix of genetic distances between taxa in a group
under study distance method A rigorous mathematical approach to alignment of
nucleotide sequences disulfide bridge A covalent bond linking cysteine amino acids on different
polypeptides or a different positions on the same
polypeptide DNA Deoxyribonucleic acid. One of the two forms of nucleic
acid in living cells. The genetic material for all cellular
lifeforms and many viruses. DNA chip technology Technology for parallel processing thousands of DNA
segments, such as for detecting mutation patterns in genomic
DNAs or expression patterns of mRNAs. DNA library A physical collection of unordered, cloned fragments of
DNA, possibly cDNA obtained from mRNA. The fragments can
come from the entire genome, but often the fragments in a
particular DNA library come from a particular tissue or
choromosome region and represent only a subset of the entire
DNA of an organism. DNA ligase An enzyme that synthexizes phophodiester bonds as part of
DNA replication, repair and recombination processes. DNA marker A DNA sequence that exists as two or more readily
distinguished versions and which can therefore be used to
mark a map position on a genetic, physical or integrated
genome map. DNA methylation refers to the chemical modification of NDA by attachment
of methyl groups, which has various regulatory functions in
prokaryotes and eukaryotes. DNA polymerase An enzyme that synthesized DNA on a DNA or RNA
template DNA replication Synthesis of a new copy of the genome DNA sequencing The process of determining the complete base pair sequece
of a target DNA string. DNA shuffling A PCR-based procedure that results in directed evolution
of a DNA sequence. domain A portion of a protein that folds independently of the
rest of the protein. domain name Refers to one of the levels of organization of the
Internet. Used to both classify and identify host
machines. domain duplication Duplication of a gene segment coding for a structural
domain in the protein product. domain shuffling Rearrangement of segments of one or more genes, each
segment coding for a structural domain in the gene product,
to create a new gene. dominance The property of an allele to manifest its entire
phenotypic effect int he heterozygote donor site The 5' end of an intron dose repitition The presence of multiple copies of a DNA sequence which
can be shown to produce increased quantities of a gene
product relative to a single copy sequence double helix The base-paired, double-stranded structure that is the
natural form of DNA in the cell. dot matrix A method of sequence alignment in which two sequences are
written as column and row headings of a matrix and dots are
put in those matrix elements that have identical column and
row headings. double restriction digest Digestion of DNA with two restriction endonucleases at
the same time. double stranded Comprising two polynucleotides attached to one another by
base pairing. download To transfer a file from a remote hsot to a local machine
via FTP downstream In the direction 3' of a reference point on a nucleic
acid. In the direction of transcription. Drosophila melanogaster Fruit fly, commonly used in genetic studies du UNIX command for determining disk usage duplex A double-stranded DNA or RNA, or a doubl ehelix formed by
the complementary pairing of a single-stranded DNA with an
RNA molecule. duplication The presence or the creation of two copies of a DNA
segment in the genome. dynamic programming A type of algorithm widely used for constructing sequence
alignments and for evaluating all possible candidate gene
structures.