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Date of Award

5-3-1996

Document Type

Restricted Thesis: Campus only access

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Dr. Valerie M. Kish

Abstract

Chlamydomonas reinhardtii serves as a very useful model system for the study of eukaryotic organisms. It is a unicellular algae which is easily grown and maintained in simple liquid media under sufficient light. Large populations of cells are easily obtainable for repeated experiments. Furthermore, the growth under alternating twelve hours of light and twelve hours of darkness produces synchronous cell division of the population as the cells divide after entering four hours of darkness (Harris 1989).

Ubiquitin is a small (8.5 kDa) 76-amino-acid protein which is understood to be present in virtually all eukaryotic organisms ranging from yeast cells to mammals (Shimogawara et al. 1989). It can exist free in the cell or conjugated to other proteins. Conjugation of ubiquitin to histones is observed; however, its particular role is not completely understood (Finley et al. 1991). Its most well-documented role is as part of an intracellular proteolytic pathway. Proteins involved in proteolysis function to recognize and eliminate unassembled proteins, dispose of damaged or misfolded proteins, or confer short half-lives on normal proteins whose concentrations must quickly change. Ubiquitin plays an essential role as part of the ATP~dependent proteolytic system in eukaryotic organisms by marking proteins for degradation. First, a ubiquitinating enzyme complex recognizes the target protein. A ubiquitin chain is then extended from a lysine amino acid on the target protein, and as a result, the proteosome complex recognizes and degrades the protein· (Finley et al. 1991). The proteosome is a large (20S) hollow protein complex which has various protein degradation capabilities (Jentsch 1992).

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