Synthesis and Stability of Chloroplast Ribosomal-RNA's.

The chloroplast ribosomal-RNAs (1.1 x 10(6) and 0.56 x 10(6) mol wt) are synthesized in the normal ratio of 2:1. The non-ribosomal distribution observed after extraction and fractionation results from the lability of the 1.1 x 10(6) component, and a correction for this breakdown can be applied in certain cases. Newly synthesized 1.1 x 10(6) RNA is more stable than the older accumulated 1.1 x 10(6) RNA. Accumulation of the chloroplast RNA during growth of radish cotyledons occurs at a later time than the accumulation of cytoplasmic RNA, and its turnover is much less than that of the cytoplasmic ribosomal-RNA.