Document Type

Thesis - Open Access

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Degree Name

Master of Science (MS)

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The development of a systematic procedure to fractionate cells into functional components is important to many current problems in biological research. Polyribosomes are of considerable interest since it is this cell fraction which is the site of protein synthesis. They are unique structures in that they are reported to contain the transcribed genetic information in the form of messenger RNA (mRNA) which functions as the binding site for ribosomes in the decoding process. A satisfactory isolation of polyribosomes provides an opportunity to analyze the nature of this transcribed genetic message and also determine the extent to which protein synthesis is controlled by the translational process. Considerable insight into current theory of the genetic code problem has come about as a result of in vitro synthesis systems that have involved isolated ribosomes. Most of these advances have been made using single cell organisms. Efforts to duplicate these results with higher plants have been sketchy. A major obstacle has been an inability to inhibit endogenous enzymes that responsible for degrading both synthetic and naturally occurring messenger RNA (mRNA). Extraction of stable polyribosomes provides reasonable assurance that single-stranded mRNA has been protected. From such preparations one would also stand the best, chance of recovering undegraded transfer RNA (tRNA) which is vital in protein synthesis but vulnerable to RNase attack. Progress toward reducing the influence of nucleases during extraction of plant tissue has been made by the use of diethyl pyrocarbonate. Weeks and Harcus have shown that it is an unstable compound although an effective one in inhibiting RNase. Should there be an interest in the isolation of immediate products resulting from the translation of the genetic message, it again important to isolate stable polyribosomes containing nascent peptides. Petermann and Pavlovec (21) have stressed the importance of eliminating the basic cytoplasmic proteins which can be randomly bound to the ribosomal particles. They found that high salt levels during extraction were essential to obtaining stable polyribosomes from muscle tissue. Thus it becomes important to not only retain the identity of the polyribosomes, but also to achieve some compartmentalization of other cell components.

Library of Congress Subject Headings



South Dakota State University Theses



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South Dakota State University