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Abstract
Based on the observation that the transformation of Escherchia coli was more efficient with pUC19 than with the larger plasmid pBR322, we hypothesized that transformation frequency is somehow affected by size. To test this hypothesis, we attempted to insert a 1.7kb lambda Nde I fragment into pUC19 to generate a plasmid (pHEL) of the same size as pBR322. The two plasmids of equal size were then to be used to transform E. coli in order to compare transformation efficiencies. After two rounds of cloning, we were unable to generate pHEL. In lieu of using pHEL and pBR322, E. coli were transformed with previously prepared plasmids of varying sizes: pUC8 (2.6 kb), pUC8 0-690 (4.3 kb), and pUC8 0-690::pKT210 (16.1 kb). The results of these transformations indicate that increasing plasmid size correlates with a decrease in transformation efficiency.