The genetic material found in the nucleus of a cell. It consists of PROTEIN and deoxyribonucleic acid (DNA). During mitotic division of the cell, chromatin condenses into CHROMOSOMES.... chromatin
A laboratory technique for identification of herbs and their constituents, taking advantage of the different rates at which molecules diffuse through an absorbent column to separate them.
Herbs are composed of alkaloids, saponins, esters, oils etc. In order to trace these in sample plant material, a picture is taken by a process known as Thin-layer-chromatography (TLC) on which a silica- gel coated ‘negative’ makes visible a number of constituents.
To initiate this process, active constituents (alkaloids etc) are extracted and separated. Their separation is possible by dipping into a special solvent solution, after which the ‘negative’ is developed by spraying with a reagent that reveals the constituents in various colours. Each component of the plant has its own distinctive colour. Each herb has its own specific ‘profile’ which can be ‘read’ by the technician and checked against known control samples. Each plant can thus be accurately identified. ... chromatography
n. one of the two threadlike strands formed by longitudinal division of a chromosome during *mitosis and *meiosis. They remain attached at the *centromere. Chromatids can be seen between early prophase and metaphase in mitosis and between diplotene and the second metaphase of meiosis, after which they divide at the centromere to form daughter chromosomes.... chromatid
n. the dispersal or disintegration of the microscopic structures within the nerve cells that normally produce proteins. It is part of the cell’s response to injury.... chromatolysis
n. abnormal coloured vision: a rare symptom of various conditions. Sometimes everything looks reddish to patients after removal of their cataracts; patients suffering from digitalis poisoning may see things in green or yellow. Similar disturbances of colour may be experienced by people recovering from inflammation of the optic nerve.... chromatopsia
*chromatin found only in female cells and believed to represent a single X chromosome in a nondividing cell. It can be used to discover the sex of a baby before birth by examination of cells obtained by *amniocentesis or *chorionic villus sampling. There are two main kinds: (1) the Barr body, a small object that stains with basic dyes, found on the edge of the nucleus just inside the nuclear membrane; (2) a drumstick-like appendage to the nucleus in neutrophils (a type of white blood cell).... sex chromatin
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