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Home >> Biotechnology Dictionary >> Gelatin - Gram-positive organism
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Gelatin - a glutinous, proteinaceous gelling and solidifying agent. Gelatin is produced by boiling animal connective tissues, which partially hydrolyses the collagen. Gelatin is used to gel or solidify nutrient solutions - for tissue culture. cf agar.
Genetic complementation - when two DNA molecules that are in the same cell together produce a function that neither DNA molecule can supply on its own. a.k.a. complementation.
Genetic disease - a disease that has its origin in changes to the genetic material. Usually refers to diseases that are inherited in a Mendelian fashion, although non-inherited forms may also result from DNA mutation.
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Gelatinisation - steam cooking of milled grain, a process that increases the surface area of the starch and converts the original mash to a material with a gel-like consistency.
Genetic distance - in AnGR: a measure of the genetic similarity between any pair of populations. Such distance may be based on phenotypic traits, allele frequencies or DNA sequences. For example, genetic distance between two populations having the same allele frequencies at a particular locus, and based solely on that locus, is zero. The distance for one locus is maximum when the two populations are fixed for different alleles. When allele frequencies are estimated for many loci, the genetic distance is obtained by averaging over these loci.
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Gelrite TM - the brand name of a Pseudomonas-derived refined polysaccharide used as a gelling agent and agar substitute.
Genetic distancing - in AnGR: the collection of the data on phenotypic traits, marker allele frequencies or DNA sequences for two or more populations, and estimation of the genetic distances between each pair of populations. From these distances, the best representation of the relationships among all the populations may be obtained. (Source: FAO, 1999).
Genetic diversity - the heritable variation within and among populations which is created, enhanced or maintained by evolutionary forces.
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GEM -
genetically engineered microorganism.
Gene addition -
the addition of a functional copy of a gene to the genome of an organism.
Gene amplification - the selective production of multiple gene copies without a proportional increase in others.
Gene bank - the physical location where collections of genetic material in the form of seeds, tissues or reproductive cells of plants or animals are stored.
Germ layers - the layers of cells in an animal embryo at the gastrula stage, from which the various organs of the animal's body will be derived.
Genetic drift - change in allele frequency from one generation to another within a population, due to the sampling of finite numbers of genes that is inevitable in all real (finite) populations. The smaller the population, the greater is the genetic drift Sooner or later (depending on the size of the population), genetic drift results in loss of alleles from a population, and hence leads to a loss of genetic variation. Because of this, the minimization of genetic drift is an important consideration for conservation of genetic resources. See genetic diversity.
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Genetic engineering - changes in the genetic constitution of cells (apart from selective breeding) resulting: from the introduction or elimination of specific genes: through modern molecular biology techniques. This technology is based on the use of a vector for transferring useful genetic information from a donor organism into a cell or organism that does not possess it.
Germ line - a lineage of 'generative' cells (= germ track) ancestral to the gametes (sperm and egg cells proper) which, during the development of an organism (animal or plant), are set aside as potential gamete-forming tissues. These ancestral cells, together with the gametes, are called germ cells, as opposed to somatic cells. Location, nature and time of formation of potential gameteforming tissues are species specific, and may vary greatly from one species to another.
Germ line cells - cells that produce gametes.
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Germ Line Gene Therapy -
the delivery of a gene or genes to a fertilised egg or an early embryonic cell. Thetransferred gene(s) is present in all or some of the nuclei of the cells of the mature individual, including possibly the reproductive cells, and alters the phenotype of the individual that develops.
Germplasm -
the genetic material that forms the physical basis of hereditary and which is transmitted from one generation to the next by means of the germ cells.
Graft inoculation test -
a test based on the use of a suspected viral carrier which is grafted to an indicator plant. If symptoms appear in the indicator plant, the viral assay is positive.
Graft union -
the point at which a scion from one plant is joined to a stock from another plant.
Gram staining -
a technique to distinguish between two major bacterial groups, based on stain retention by their cell walls. Bacteria are heat-fixed, then stained with crystal violet, followed by iodine solution, and then rinsed with alcohol or acetone. Gram-positive bacteria are stained bright purple, while Gram-negative bacteria are decolourised.
Gram-negative organism -
any prokaryotic organism that does not retain the first stain (crystal violet) used in Gram's staining technique. It does retain the second stain (safranin O) and therefore has a pink colour when viewed under a light microscope. Retention of the stain is due to the structure of the cell wall.
Gram-positive organismany - any prokaryotic organism that retains the first stain used in the Gram technique, which gives a purple-black colour when viewed under a light microscope. Retention of the stain is due to the structure of the cell wall.
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