guanylic acidSynonym for guanosine monophosphate (abbreviation: GMP), a (ribo)nucleotide containing the.
guard cellSpecialized epidermal cells found in pairs around a stoma. Their function is to control the opening and closing of the stoma through changes in turgor.
guide RNAAn RNA molecule that contain sequences that function as a template during RNA editing. See: guide sequence.
guide sequenceAn RNA molecule (or a part of it) which hybridizes with eukaryotic mRNA and aids in the splicing of intron sequences.
GURTAbbreviation for genetic use restriction technology.
gus geneAn E. coli gene that encodes for production of beta-glucuronidase (GUS). Because this activity is absent in plants, the gene is commonly utilized as a…
GyandromorphOrganisms that have both male and female cells and therefore express both male and female characteristics.
gymnospermA class of plant (e.g. conifers) whose ovules and the seeds into which they develop are borne unprotected, rather than enclosed in ovaries, as are those…
gynandromorphAn individual in which one part of the body is female and another part is male; a sex mosaic.
gynogenesisFemale parthenogenesis : after fertilization of the ovum, the male nucleus is eliminated and the haploid (gynogenetic) individual possesses the maternal…
HPrefix used to designate the human form of an enzyme. For example, hGH is human growth hormone.
habituationThe phenomenon whereby, after a number of sub-cultures, cells can grow without the addition to the tissue culture medium of previously obligatory factors.
haemoglobinProtein containing iron, located in erythrocytes of vertebrates; important for the transportation of oxygen to the cells of the body.
haemolymphThe mixture of blood and other fluids in the body cavity of an invertebrate.
haemophiliaA sex-linked hereditary bleeding disorder in which it takes a long time for the blood to clot and abnormal bleeding occurs.
hairpin loopA region in one strand of a polynucleotide which, due to an inverted repeat in the sequence, may under appropriate conditions fold back on itself and form…
hairy root cultureA culture consisting of highly branched roots of a plant. A plant tissue is treated with the bacterium Agrobacterium rhizogenes containing the Ri plasmid…
hairy root diseaseA disease of broad-leaved plants, where a proliferation of root-like tissue is formed from the stem.
halophyteA plant species adapted to soils containing a concentration of salt that is toxic to most plant species. See: salt tolerance.
Hanging drop methodA technique used to culture embryonic stem cells so that they develop into embryoid bodies.
HaploidA cell or organism containing one of each of the pairs of homologous chromosomes found in the normal diploid cell.
Haploid cellA cell containing only one set, or half the usual (diploid) number, of chromosomes.
Haploid human cellA cell such as an egg or sperm that contains only twenty-three chromosomes.
haploinsufficiencyA situation in which the protein produced by a single copy of an otherwise normal gene is not sufficient to assure normal function. See also gene, protein
HaplotypeA specific allelic constitution at a number of loci within a defined linkage block.
haptenA small molecule, which by itself is not an antigen, but which as a part of a larger structure when linked to a carrier protein, can serve as an antigenic…
haptoglobinA serum protein that interacts with haemoglobin during recycling of the iron molecule of haemoglobin. Synonym: alpha globulin.
hardening offAdapting glasshouse or controlled environment grown plants to outdoor conditions by reducing availability of water, lowering the temperature, increasing…
Hardy-Weinberg equilibriumThe frequencies of genotypes at a locus resulting from random mating at that locus; for two alleles, A1 and A2, with respective frequencies in a…
HarvestingThe process of retrieving or collecting electronic data from storage media or devices; an EDiscovery vendor harvests electronic data from computer hard…
heat shock protein(... PROH-teen) One of a group of proteins that help protect cells from stresses such as heat, cold, and low amounts of oxygen or glucose (sugar).
helixA structure with a spiral shape. The normal state of double-stranded DNA is in the form of a double helix.
helminthA class of parasitic worms, especially those which are internal parasites of man and animals.
helper cellT cells that assist in stimulating B and T lymphocyte s to develop into antibody-producing plasma cells and killer T cells, respectively.
helper plasmidA plasmid that provides a function or functions to another plasmid in the same cell.
helper T cellA type of white blood cell that helps stimulate immune system reactions. Helper T cells help activate cytotoxic T cells and macrophages by secreting…
helper virusA virus that provides a function or functions to another virus in the same cell.
Hematological OncologistA medical doctor who specializes in diagnosing and treating malignancies, or cancers, of the blood and blood- forming tissues.
Hematologist(HEE-muh-TAH-loh-jist) A doctor who specializes in treating blood disorders.
Hematopoiesis(hee-MA-toh-poy-EE-sus) The formation of new blood cells.
Hematopoietic cell transplantationThe transplantation of hematopoietic stem cells with blood-forming potential. Hematopoietic stem cells provide rapid and sustained reconstitution of blood…
Hematopoietic stem cellAn unspecialized precursor cell that will develop into a mature blood cell. See also cell
Hematopoietic stem cellsThe precursors of mature blood cells that are defined by their ability to replace the bone marrow system following its obliteration (for example, by…
hemicellulaseAn enzyme that catalyses the degradation of hemicellulose.
hemicelluloseAny cellulose-like carbohydrate, but excluding cellulose itself. Together with pectin and lignin, hemicelluloses form the cell wall matrix.
HemizygousThe condition in which genes are present only once in the genotype and not in pairs.
hemoglobin(HEE-moh-GLOH-bin) The substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues.
herbicide resistanceThe ability of a plant to remain unaffected by the application of a herbicide.
Herbicide-tolerant cropCrop plants that have been developed to survive application(s) of one or more commercially available herbicides by the incorporation of certain gene(s)…
Hereditary cancerCancer that occurs due to the inheritance of an altered gene within a family. See also: sporadic cancer
heredityResemblance among individuals related by descent; transmission of traits from parents to offspring.
heritabilityThe degree to which a given trait is controlled by inheritance, as opposed to being controlled by non-genetic factors.
hermaphrodite1. An animal that has both male and female reproductive organs, or a mixture of male and female attributes. 2.
hES cellHuman embryonic stem cell; a type of pluripotent stem cell.
heteroalleleA gene having mutations at two or more different sites.
HeterochromatinDark-stained regions of chromosomes thought to be for the most part genetically inactive.
HeteroduplexA double-stranded DNA molecule or DNA-RNA hybrid, where each strand is of a different origin.
heteroduplex analysisThe use of the electrophoretic mobility of to estimate the degree of non-homology between the sequences of the two strands.
heterogameticProducing unlike gametes with regard to the sex chromosomes. In mammals, the XY male is heterogametic, and the XX female is homogametic.
heterogeneous nuclear RNA(Abbreviation: hnRNA ). Large RNA molecules, which are found in the nucleus of a eukaryotic cell and the precursors of mRNA and other RNA molecules.
Heterogeneous nuclear RNA (hnRNA)The name originally given to large RNA molecules found in the nucleus, which are now known to be unedited mRNA transcripts, or pre-mRNAs. (See RNA.)
heterokaryonA cell with two or more different nuclei as a result of cell fusion. See: synkaryon.
heteroplasmyA condition in which two genetically different organelles are present in the same cell. The equivalent to heterozygous in the context of nuclear genes.
heteroploidCells with nuclei containing chromosome numbers other than diploid.
heteropyknosisThe property of certain chromosomes, or of their parts, to remain more dense during the cell cycle and to stain more intensely than other chromosomes or…
heterotrophOrganism non capable of self-nourishment utilizing carbon dioxide or carbonates as the sole source of carbon and obtaining energy from radiant energy or…