Cistrons Among Yeast Chromosomes
نویسنده
چکیده
High-molecular-weight deoxyribonucleic acid (DNA) of Saccharomyces carlsbergensis has been fractionated by sucrose density gradient centrifugation. The main DNA fraction has an average molecular weight of about 500 x 106. A major fraction of the DNA molecules containing sequences homologous to ribosomal ribonucleic acid (RNA) sediments as material of this molecular weight. The remainder sediments as material of a molecular weight of about 250 x 10g. The latter fraction contains relatively more ribosomal RNA cistrons than the former. Studies on the buoyant density of high-molecular-weight DNA homologous to ribosomal RNA have led to the conclusion that the ribosomal RNA cistrons occur in groups attached to a relatively large amount of nonribosomal RNA and suggest that ribosomal RNA cistrons are distributed over a number of yeast chromosomes.
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