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  Home >> Molecular Biology Dictionary >> GMP Guanosine Monophosphate Guanosine - Gravitropism Geotropism

GMP
(guanosine monophosphate) See guanosine.

Gobar
See biogas.

Golgi apparatus
An assembly of vesicles and folded membranes within the cytoplasm of plant and animal cells that stores and transports secretory products (such as enzymes and hormones) and plays q role in formation of a cell wall (when this is present). It is named after its discoverer, the Italian cytologist Camillo Golgi (1843-1926).

Gonad
Any of the usually paired organs in animals that produce reproductive cells (gametes). The most important gonads are the male testis, which produces spermatozoa, and the female ovary, which produces ova (egg cells). The gonads also produce hormones that control secondary sexual characteristics.

Good laboratory practice
See GLP/GMP.

Grana
(L. granum, a seed) Structures within chloroplasts, seen as green granules with the light microscope and as a series of parallel lamellae with the electron microscope. Disc or sac like structures found in chloroplasts composed of stacked membranes and containing the chlorophyll and carotenoid pigments directly involved in photosynthesis (singular: granum).

GRAS
See generally regarded as safe.

Good manufacturing practice.
See GLP/GMP.

Graft (to)
To place a detached branch (scion) in close cambial contact with a rooted stem (rootstock) in such a manner that scion and rootstock unite to form a single plant.

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.

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 organism
Any prokaryotic organism that retains the first stain used in the Gram technique, which gives a purple black colour when viewed under alight microscope. Retention of the stain is due to the structure of the cell wall.

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 decolourized.

Gratuitous inducer
A substance that can induce transcription of a gene or genes, but is not a substrate for the induced enzyme(s).

Gravitropism .
See geotropism.

 

 

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