Date of Award

Fall 1972

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Biology

Abstract

The synthesis of ribosomal ribonucleic acid(rRNA) during amino acid starvation and nitrogen starvation was studied in stringent and relaxed strains of Escherichia coli. Acrylamide agarose composite gel was used for analyzing different species of rRNA. The rRNA extracted from leucine starved stringent and relaxed bacteria and from nitrogen starved relaxed cells were in the precursor forms (pl6 and p23 S RNA). These precursors could mature into the normal mature rRNA(m16 and m23 S RNA) after leucine or (NH4) 2so4 was restored to the starved cultures. The effect of amino acid starvation and nitrogen starvation on the maturation of rRNA is thought to be related to the assembly of ribosomes. The assembly process includes sequential binding of ribosomal proteins to the RNA molecules in addition to the methylation and cleavage of the RNA. Once protein synthesis has stopped by depriving cells of a required amino acid or inorganic nitrogen, precursors of rRNA accumulate. This blockage of maturation is interpreted to be due to a lack of critical ribosomal proteins which bind to the RNA molecule prior to the cleavage step during ribosome assembly.

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