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Question
As indicated in the gel image, lanes X and Y represent samples obtained from a circular plasmid DNA after complete digestion using restriction enzyme X or Y with different recognition sites, respectively. How many sites for X and Y are present in the plasmid (sizes of the bands in kilo base pairs(kb) is shown)?
As indicated in the gel image, lanes X and Y represent samples obtained from a circular plasmid DNA after complete digestion using restriction enzyme X or Y with different recognition sites, respectively. How many sites for X and Y are present in the plasmid (sizes of the bands in kilo base pairs(kb) is shown)?
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Solution
The correct option is B 2 for X, 1 for Y
From the image, the circular plasmid is 10 kb in size. Lane X is showing 2 bands of 4 kb and 6 kb size. Hence, there are 2 restriction sites for restriction enzyme X. One restriction site will make the circular plasmid linear and another restriction site will make a cut at 4 kb. Similarly, there are 2 restriction sites for restriction enzyme Y. One restriction site will make the circular plasmid linear and other restriction sites will make a cut at 5 kb. Since both fragments are of 5 kb size, the only single band is seen in lane Y.Thus, the correct answer is option D.
From the image, the circular plasmid is 10 kb in size. Lane X is showing 2 bands of 4 kb and 6 kb size. Hence, there are 2 restriction sites for restriction enzyme X. One restriction site will make the circular plasmid linear and another restriction site will make a cut at 4 kb. Similarly, there are 2 restriction sites for restriction enzyme Y. One restriction site will make the circular plasmid linear and other restriction sites will make a cut at 5 kb. Since both fragments are of 5 kb size, the only single band is seen in lane Y.
Thus, the correct answer is option D.
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