Unformatted text preview: erhelical tension in DNA.
The DNA sequence shown below contains inverted repeats that form a cruciform structure in negatively
supercoiled DNA (see part B in the figure shown below). Cruciform structure can be detected by
electrophoresis after cleavage of the DNA by Endo VII. Endo VII introduces bilateral cleavages close to
the cruciform/B-DNA junction, generating a double-strand break. A restriction enzyme Ava I is also used
in the assay to linearize the DNA. The site of cleavage by the AvaI restriction enzyme is shown in Part A
in the figure. Three different versions of the DNA substrate shown in part A are used. In lanes 1- 4, the substrate is supercoiled. In lanes 5- 8, the substrate has been linearized prior to the assay using AvaI. In lanes 9- 12, the substrate is a relaxed circular DNA. Note that relaxed circular DNA migrates slower on the gel than the linear form. Please answer the following questions based on the data shown in Part C: A. (5 points)...
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