A Novel Type of Gene Organization in Eukaryotic Chromosomes
Only two types of organization of the structural genes in the eukaryotes have been known until recently. Most of the genes are represented by unique sequences occurring one per genome. The genes for globins, ovalbumin, fibroin, albumin, crystallins and many other can be mentioned as examples. It is suggested that unique genes are surrounded by DNA sequences which do not encode any protein but may participate in the regulation of expression of the particular gene. It was found with D.melanogaster that one band in a polytene chromosome containing about 20–30 kb per single DNA strand on the average corresponds approximately to one gene or, more precisely, to one complementation group. This indicates the existence of excess DNA in a genome which may be involved in regulation and other service functions. The location of unique genes along the chromosome is strictly fixed.
KeywordsStructural Gene Unique Gene Gene Organization Polytene Chromosome Histone Gene
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