Biotechnology and Genetics terms starting with D

201 terms

D loop Abbreviation for displacement loop. Formed when a short stretch of RNA is paired with one strand of DNA.
dA - dT tailing See complementary homopolymeric tailing.
DAB (Full term: single domain antibody ). Antibodies with only one (instead of two) protein chain derived from only one of the two domains of the normal…
DAF See: DNA amplification fingerprinting.
Dalton A unit of measurement equal to the mass of a hydrogen atom, 1.67 x 10E-24 gram/L (Avogadro's number).
DAMD See: directed amplification of minisatellite DNA.
Darwinian cloning Selection of a clone from a large number of essentially random starting points, rather than isolating a natural gene or making a carefully designed…
Data warehouse A collection of databases, data tables, and mechanisms to access the data on a single subject.
dATP Abbreviation for deoxyadenosine 5'-triphosphate. dATP is required for DNA synthesis since it is a direct precursor molecule. See: adenosine, adenylic acid.
dCTP Abbreviation for deoxycytidine 5'-triphosphate. dCTP is required for DNA synthesis since it is a direct precursor molecule. See: cytidine, cytidylic acid.
ddNTP Abbreviation for di-deoxynucleotide.
de-differentiation The process, in response to wounding and in tissue cultures, by which plant cells can become unspecialized and start to proliferate by cell division to…
de-ionized water Water from which most salts have been removed - with varying degrees of efficiency - by ion exchange.
Death phase The final growth phase, during which nutrients have been depleted and cell number decreases. (See Growth phase).
deceleration phase The phase of declining growth rate, following the linear phase and preceding the stationary phase in most batch-suspension cultures. See: growth phase.
Decidual cells A cellular matrix that first surrounds an implanted embryo and later occupies most of the endometrium.
defective virus A virus that, by itself, is unable to reproduce when infecting its host cell, but that can grow in the presence of another virus.
deficiency (dih-FIH-shun-see) In medicine, a shortage of a substance (such as a vitamin or mineral) needed by the body.
defined 1. Fixed conditions of medium, environment and protocol for growth. 2. Precisely known and stated elements of a tissue culture medium.
degeneracy The specification of one amino acid by more than one codon. It arises from the inevitable redundancy resulting from the 64 possible codons encoding only…
degeneration 1. Changes in cells, tissues or organs due to disease. 2. The reduction in size or complete loss of organs during evolution.
dehalogenation The removal of halogen atoms (fluorine, chlorine, bromine, iodine) from molecules, for example during biodegradation.
dehiscence The spontaneous and often violent opening of a fruit, seed pod or anther to release and disperse the seeds or pollen.
dehydrogenase An enzyme that catalyses the removal of hydrogen atoms in biological reactions.
dehydrogenation A chemical reaction in which hydrogen is removed from a compound.
Deletion Deletion is the process whereby data is removed from active files and other data storage structures on computers and rendered inaccessible except using…
Deletion map A description of a specific chromosome that uses defined mutations --specific deleted areas in the genome-- as 'biochemical signposts,' or markers for…
deliberate release In a biotechnology context, the intentional release of genetically modified organisms.
delta endotoxins See: cry proteins.
deme A group of organisms in the same taxon.
demineralize To remove the mineral content (salts, ions) from a substance, especially water. Removal methods include distillation, electrodialysis and ion exchange.
Denature To induce structural alterations that disrupt the biological activity of a molecule.
denatured DNA Double-stranded DNA that has been converted to single strands by breaking the hydrogen bonds linking complementary nucleotide pairs. Often reversible.
denatured protein Altering the in vivo conformation of a protein by heat or salt treatment, thereby destroying its biological activity.
denaturing gradient gel electrophoresis (Abbreviation: DGGE ). An electrophoresis method for separating similar sized DNA fragments on the basis of their sequence, by applying across the gel a…
dendrimer A polymer that repeatedly branches until stopped by the physical constraint of having formed a complete, hollow sphere.
Dendrite Extension of a nerve cell, typically branched and relatively short, that receives stimuli from other nerve cells.
denitrification A chemical process in which nitrates in the soil are reduced to molecular nitrogen, which is released to the atmosphere.
Density gradient centrifugation High-speed centrifugation in which molecules "float" at a point where their density equals that in a gradient of cesium chloride or sucrose.
Dental pulp The soft part inside a tooth, containing blood vessels and nerves.
deoxyadenosine See: adenosine, dATP.
deoxycytidine A drug that protects healthy tissues from the toxic effects of anticancer drugs.
deoxyguanosine See: guanosine, dGTP.
deoxyribonuclease See: DNase.
deoxyribonucleic acid (dee-OK-see-RY-boh-noo-KLEE-ik A-sid) The molecules inside cells that carry genetic information and pass it from one generation to the next.
Deoxyribonucleic Acid (DNA) a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses.
deoxyribonucleoside See: nucleoside.
Deoxyribonucleotide See: nucleotide.
Deoxyribose A type of sugar that is one component of DNA (deoxyribonucleic acid).
deoxyribose (2-deoxyribose) See: ribose.
deoxythymidine Strictly correct but rarely used synonym for thymidine.
derepression The process of "turning on" the expression of a gene or set of genes whose expression has been repressed (turned off), usually by the displacement of a…
Derivative Derivatives are financial products, such as futures contracts, options, and mortgage-backed securities.
Desiccant Any compound used to remove moisture or water.
desoxyribonucleic acid Obsolete spelling of deoxyribonucleic acid.
desulphurization See: biodesulphurization.
detergent Substance which lowers the surface tension of a solution, improving its cleaning properties.
determinate growth Growth determined and limited in time, with a bud or flower terminating the growth of the main axis. Once established, it is usually irreversible.
determination Process by which undifferentiated cells in an embryo become committed to develop into specific cell types, such as neurons, fibroblasts or muscle cells.
determined Describing embryonic tissue at a stage when it can develop only as a certain kind of tissue.
development The sum total of events that contribute to the progressive elaboration of an organism. The two major aspects of development are growth and differentiation.
deviation 1. An alteration from the typical form, function or behaviour. Mutation or stress are the common reasons behind deviation. 2.
dextrin An intermediate polysaccharide compound resulting from the hydrolysis of starch to maltose by amylase enzymes.
dG - dC tailing See: complementary homopolymeric tailing.
DGGE See: denaturing gradient gel electrophoresis.
dGTP Abbreviation for deoxyguanosine 5'-triphosphate. dGTP is required for DNA synthesis since it is a direct precursor molecule. See: guanosine, guanylic acid.
di-deoxynucleotide (Abbreviations: ddNTP,didN). A synthetic deoxynucleotide that lacks a 3'-hydroxyl group, and is thus unable to form the 3'?
Diabetes Any of several diseases in which the kidneys make a large amount of urine. Diabetes usually refers to diabetes mellitus in which there is also a high…
diabetes mellitus (dye-a-BEE-teez MEL-ih-tus) A group of disorders in which there is a defect in the transfer of glucose (sugar) from the bloodstream into cells, leading to…
diagnostic procedure A method used to identify a disease.
diakinesis A stage of meiosis at the end of prophase I, in which the contraction of the chromosomes is almost at a maximum, pairing configurations are well defined…
dialysis (dye-AL-ih-sis) The process of filtering the blood when the kidneys are not able to cleanse it.
diazotroph An organism that can fix atmospheric nitrogen.
dicentric chromosome A chromosome having two active centromeres.
dichogamy The condition in which the male and the female reproductive organs of a flower (or certain hermaphroditic animals) mature at different times, thereby…
dicot See: dicotyledon.
dicotyledon (Abbreviation: dicot). A plant with two cotyledons . One of the two major classes of flowering plants (along with the monocotyledons ).
Dideoxynucleotide (didN) A deoxynucleotide that lacks a 3' hydroxyl group, and is thus unable to form a 3'-5' phosphodiester bond necessary for chain elongation.
didN See Dideoxynucleotide.
differential centrifugation A method for separating sub-cellular particles according to their sedimentation coefficients, which are roughly proportional to their size.
differential display A method to identify mRNAs which are present at different levels in different tissues, or in response to specific treatments.
differentially permeable Referring to a membrane, through which different substances diffuse at different rates.
Differentiation In cancer, refers to how mature (developed) the cancer cells are in a tumor. Differentiated tumor cells resemble normal cells and tend to grow and spread…
diffusion The spontaneous movement of molecules from a region of higher concentration to a region of lower concentration.
digest To cut DNA molecules with one or more restriction endonucleases.
dihaploid An individual which arises from a doubled haploid.
dihybrid An individual that is heterozygous for two pairs of alleles; the progeny of a cross between homozygous parents differing at two loci.
dimer 1. A molecule formed by the covalent combination of two monomers, generally accompanied by elimination of water. 2.
dimethyl sulphoxide (Abbreviation: DMSO). A highly hygroscopic liquid and powerful solvent with little odour, colour or toxicity when pure.
dimorphism The existence of two distinctly different types of individuals within a species. An obvious example is sexual dimorphism in mammals.
dinucleotide A nucleotide dimer.
dioecious A plant species in which male and female flowers form on different plants.
diplochromosome See: endoreduplication.
Diploid The status of having two complete sets of chromosome s, most commonly one set of paternal origin and the other of maternal origin.
Diploid cell A cell which contains two copies of each chromosome. See Haploid cell.
Diploid human cell A cell having forty-six chromosomes.
diplonema Stage in prophase I of meiosis following the pachytene stage, but preceding diakinesis, in which one pair of sister chromatids begin to separate from the…
diplotene (adj.) See diplonema.
direct embryogenesis The formation in culture, on the surface of zygotic or somatic embryos or on explant tissues (leaf section, root tip, etc.
direct organogenesis Formation of organs directly on the surface of cultured intact explants . The process does not involve callus formation. Opposite: indirect organogenesis.