Satellited Chromosome

a chromosome that carries on one of its ends a round or elongated body (satellite) attached to the chromosome by a thin strand (secondary constriction). The number of satellited chromosomes is constant for each species. The size and shape of satellites and constrictions may vary considerably from chromosome to chromosome but are comparatively constant for each individual chromosome. The area of a secondary constriction remains despiralized throughout the entire cell cycle. The genes responsible for the synthesis of the ribosomal ribonucleic acid that reaches the nucleolus are located in this area. Secondary constrictions are called nucleolar organizers because they participate in the formation of nucleoli. The number of satellited chromosomes in a cell usually corresponds to the number of nucleoli.