113 Cytotaxonomy The characterization and identification of a cells complete

113 cytotaxonomy the characterization and

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1.1.3 Cytotaxonomy The characterization and identification of a cell’s complete chromosome set is referred to as karyotyping . It is the first stage in the
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7 process of using chromosomes in taxonomy. Karyotypes within interbreeding populations of a species are usually constant. Between species there may be variation in chromosome number and size. Final stages of chromosomal aberrations such as inversions and translocations can give clues regarding intermediary stages. 1.1.4 Chemotaxonomy Chemotaxonomy refers to the use of information about small molecules produced by the action of enzymes. Protein fractions in electrophoretic techniques, identification of amino acids in chromatography, prevalence of isoenzymes in tissue materials are all tools employed in chemotaxonomy. The occurrence of specific pheromones, colour pigments, toxins also help as keys in taxonomy. 1.1.5 Palaeotaxonomy This method depends on identification and dating of fossils. Availabil- ity of a good complete fossil provides better chance for identification. In several fossils, their sections taken through laborious pro- cesses have provided the identification features. The fossils are normally studied along with other accompanying fos- sils, its geographic location and other factors. Even though it is possible to assign a fossil to a genus or other higher level, fixing the species is not always possible. 1.1.6 Nomenclature methods Nomenclature forms the basis by which scientists can name and cross refer to organisms. It is an integral part of taxonomy. In fact, modern tax- onomy started in 1753 with the publication of first part of Systema by Linnaeus . According to Linnaeus a Species is specified by the combination of both its specific and generic names. Since it requires two names, it is referred to as the binomial system . This system is now firmly established in Biology. In modern times International Commissions are responsible for nam- ing each major group of organisms. There are several such commissions. These commissions authorize the usage of scientific names in biology. Naming of animals is monitored by International Code of Zoological Nomenclature (ICZN) (International Commission of Zoological Nomenclature, 1985). The rules are set out in the ‘codes’. The codes are modified by occasional science congresses.
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