Honors Theses
Date of Award
2008
Document Type
Undergraduate Thesis
Department
Chemistry and Biochemistry
First Advisor
Michael Mossing
Relational Format
Dissertation/Thesis
Abstract
Synthetic genetic circuits were constructed to observe the dynamics of repression by the Cro and scCro repressors. Each circuit contained at least one repressor and a reporter gene. Cro repressor is one of two opposite repressors. This artificial switch also had a single-chain cro (scCro) protein that would not have to dimerize like Cro to be fimctional. Such repressors bind operator sites to prevent fiirther transcription fi-om the promoters. The Lac Repressor (LacR) was used to prevent transcription firom Pr. The inducer EPTG was used to remove the Lac Repressor. A reporter gene LacZ is transcribed from Pr. The protein product of the lacZ gene is beta-galactosidase. The levels of beta-galactosidase in the cell indicate the degree of repression of Pr. Another reporter gene called Green Fluorescent Protein (GFP) was also used to observe the magnitude of repression by Cro. Three lambda operator variants were used to determine how Cro bound to each operator and how this affected the expression of the reporter GFP. Both beta-galactosidase assays and GFP assays were preformed to observe repression by Cro and scCro. The results showed that the consensus operator OrC bound Cro and scCro the best and OrT did not bind the repressors. In addition, the presence of the extra operator on the GFP plasmid did not have great effect on the degree of repression in the genome. It was also observed that repression by scCro by greater than Cro because scCro does not need to dimerize to be functional.
Recommended Citation
Sarker, Shabnam, "The Magnitude of Repression by Cro Protein in the Presence of Lambda Operator Variants" (2008). Honors Theses. 2256.
https://egrove.olemiss.edu/hon_thesis/2256
Accessibility Status
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