DNA diagnosisThe use of DNA polymorphisms to detect the presence of a disease gene.
DNA diagnosticsThe use of DNA polymorphisms to detect the presence of a specific sequence, which could indicate the presence of a contaminant, of a pathogen, or of a…
DNA fingerprintThe unique pattern of DNA fragments identified by Southern hybridization (using a probe that binds to a polymorphic region of DNA) or by polymerase chain…
DNA fingerprintingThe derivation of unique patterns of DNA fragments obtained using a number of marker techniques; historically these were RFLPs, but latterly they are…
DNA helicaseAn enzyme that catalyses the unwinding of the complementary strands of a DNA double helix. Synonym: gyrase.
DNA hybridizationThe annealing of two single-stranded DNA molecules, possibly of different origin, to form a partial or complete double helix.
DNA polymorphismOne of two or more alternate forms (alleles) of a chromosomal locus that differ in nucleotide sequence or have variable numbers of repeated nucleotide…
DNA primaseAn enzyme that catalyses the synthesis of the short strands of RNA that initiate the synthesis of DNA strands.
DNA repairA variety of mechanisms that repair errors (e.g. the incorporation of a non-complementary nucleotide) that occur naturally during DNA replication.
DNA repair genesGenes encoding proteins that correct errors in DNA sequencing.
DNA replication(⦠reh-plih-KAY-shun) The process by which a copy of the DNA in a cell is made before the cell divides.
DNA sequenceThe relative order of base pairs, whether in a DNA fragment, gene, chromosome, or an entire genome. See also: base sequence analysis
DNA sequencingProcedures for determining the nucleotide sequence of a DNA fragment.
DNA topo-isomeraseAn enzyme that catalyses the introduction or removal of supercoils in DNA. Synonym: topo-isomerase.
DollyUnlike the French roulette where the croupier simply points with the stick on the winning number on the table, in the American roulette the croupier uses…
DomainA sub-network of servers and computers within a LAN. Domain information is useful when restoring backup tapes, particularly of email.
DominantAn allele is said to be dominant if it expresses its phenotype even in the presence of a recessive allele. See Allele, Phenotype, Recessive.
Dominant geneA gene whose phenotype is when it is present in a single copy.
dominant marker selectionSelection of cells via a gene encoding a product that enables only the cells that carry the gene to grow under particular conditions.
dominant selectable markerA gene that allows the host cell to survive under conditions where it would otherwise die. Synonym: positive selectable marker.
Dominant(-acting) oncogeneA gene that stimulates cell proliferation and contributes to oncogenesis when present in a single copy. (See Oncogene.)
donor junction siteThe junction between the 5' end of an exon and the 3' end of an intron. See: acceptor junction site.
DormancyA period in which a plant does not grow, awaiting necessary environmental conditions such as temperature, moisture, nutrient availability.
dosage compensationA regulatory mechanism for sex-linked genes, to allow equivalent levels of gene expression from (in mammals) XY or XX genotypes, even though the gene copy…
double crossing-overThe formation of two chiasmata within a chromosome arm, leading to the generation of a double recombinant gamete with respect to genes located within the…
double fertilizationA process, unique to flowering plants, in which two male nuclei, which have travelled down the pollen tube, separately fuse with different female nuclei…
Double helixDescribes the coiling of the antiparallel strands of the DNA molecule, resembling a spiral staircase in which the paired bases form the steps and the…
double recessiveAn organism homozygous for a recessive allele at each of two loci.
double-stranded DNA(Abbreviation: dsDNA ). Two complementary strands of DNA annealed in the form of a double helix. Synonym: duplex DNA.
doubling time(DUH-bling...) In biology, the amount of time it takes for one cell to divide or for a group of cells (such as a tumor) to double in size.
down promoter mutationA mutation that decreases the frequency of initiation of transcription. This leads to a fall in the level of mRNA compared to the wild type state.
down-regulateTo induce genetically a reduction in the level of a gene's expression.
downstreamThe region extending in a 3' direction from a gene.
downstream processingA general term for biotechnological processes which follow the biology, i.e. fermentation of a micro-organism or growth of a plant.
Draft sequenceThe sequence generated by the HGP as of June 2000 that, while incomplete, offers a virtual road map to an estimated 95% of all human genes.
Drosophila melanogasterThe fruit fly, used for many years as a model for eukaryotic genetics. Of the nearly 300 disease-causing genes in the human genome, more than half have an…
drugAny substance, other than food, that is used to prevent, diagnose, treat or relieve symptoms of a disease or abnormal condition.
drug deliveryMethod by which a drug is delivered to its site of action. For traditional drugs this is another name for formulation.
dry weightThe weight of tissue obtained following sufficiently prolonged oven-drying at high temperature to remove all water.
dTTPRarely used but strictly correct abbreviation for deoxythymidine 5'-triphosphate. Required for DNA synthesis since it is a direct precursor molecule.
dual cultureA culture made of a plant tissue and one organism (such as a nematode) or an obligate parasite/micro-organism (such as a fungus).
EBVA common virus that remains dormant in most people. It causes infectious mononucleosis and has been associated with certain cancers, including Burkitt…
EcologyThe study of the interactions of organisms with their environment and with each other.
economic trait locus(Abbreviation: ETL). A locus influencing a trait that contributes to producer's income.
EcosystemA complex ecological community or environment forming a functioning whole.
ecotypeA population or a strain of an organism that is adapted to a particular habitat.
EctodermThe outer of three germ layers of the early embryo that gives rise in later development to the skin, cells of the amnion and chorion, nervous system…
ectopicAnomalous situation or relation, particularly with respect to pregnancy, where the foetus is implanted outside the uterus.
edible vaccineEdible antigen-containing material, that activates the immune system via gut-associated lymphoid tissues.
elastinA fibrous protein that is the major constituent of the yellow elastic fibres of animal connective tissue.
electro-blottingThe electrophoretic transfer of DNA, RNA or protein from a gel, in which they have been separated, to a support matrix, such as nitrocellulose.
electrochemical sensorBiosensors, such as an enzyme electrode, in which a biological process is harnessed to an electrical sensor system.
electron microscope(ee-LEK-tron MY-kroh-SKOPE) A microscope (device used to magnify small objects) that uses electrons (instead of light) to produce an enlarged image.
Electrophoresisa technique for the separation of charged molecules by migration on a support medium under the influence of an electrical charge.
ElectroporationA method for transforrning DNA, especially useful for plant cells, in which high voltage pulses of electricity are used to open pores in cell membranes…
ELISAAbbreviation for enzyme-linked immunosorbent assay. An immunoassay, i.e. an antibody -based technique for the diagnosis of the presence and quantity of…
elite treeA phenotypically superior tree in a tree breeding programme.
Ellis - van Creveld syndromeA rare autosomal recessive disorder that leads to dwarfism, extra fingers, and malformations of the heart, among other abnormalities. See also malformation
elongation factorsSoluble proteins required for the elongation of polypeptide chains on ribosomes.
EmbryoEarly stage in the development of a plant or an animal. In vertebrate animals (have a backbone or spinal column), this stage lasts from shortly after…
embryo cloningThe creation of identical copies of an embryo by embryo splitting or by nuclear transfer from undifferentiated embryonic cells.
embryo multiplication and transfer(Abbreviation: EMT). The cloning of animal embryos and their subsequent transfer to recipients via artificial inembryonation.
embryo rescueA sequence of tissue culture techniques utilized to enable a fertilized immature embryo resulting from an interspecific cross to continue growth and…