After radioactive labelling of the 5' end of the clones of a 10-base segment of DNA, they were randomly broken at A, C, G, and T bases. The length of each fragment was determined from an autoradiographed gel. The fragments that broke at A were 3, 5 and 10 bases long, fragments that broke at C were 1, 2 and 7 bases long, at a G were 4 and 6 bases long, and at a T were 8 and 9 bases long. The nucleotide sequence of the original clone must have been
A) 3' -CCAGAGCTTA- 5'.
B) 5' -CCAGAGCTTA- 3'.
C) 5' -CCAGAGCTTA-5'.
D) 3' -AATCATCACA- 5'.
E) 5' GGUCUCGAAU 3'.

Question

Quizplus · Accepted Answer

The fragments lengths indicate the positions of the bases relative to the 5' end. The sequence can be deduced by arranging the fragments in order: 1 and 2 (C), 3 (A), 4 and 6 (G), 5 (A), 7 (C), 8 and 9 (T), and 10 (A). This results in 5' -CCAGAGCTTA- 3'.

After Radioactive Labelling of the 5' End of the Clones