NCERT Class 12 Biology: Chapter –6 Molecular Basis of Inheritance Part 13

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Question 9:

Replication was allowed to take place in the presence of radioactive deoxynucleotides precursors in E.coli that was a mutant for DNA ligase. Newly synthesised radioactive DNA was purified and strands were separated by denaturation. These were centrifuged using density gradient centrifugation. Which of the following would be a correct result?

Chapter-6- Question -9-a- Image of These were Centrifuged Us …

These Were Centrifuged Using Density Gradient Centrifugation

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Chapter-6- Question -9-b- Image of These were Centrifuged Us …

These Were Centrifuged Using Density Gradient Centrifugation

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Chapter-6- Question -9-c- Image of These were Centrifuged Us …

Centrifuged Using Density Gradient Centrifugation

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Chapter-6- Question -9-d- Image of These were Centrifuged Us …

These Were Centrifuged Using Density Gradient Centrifugation

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Answer:

1. In the above case as replication could take place in the presence of radioactive deoxynucleotides precursors in E. coli that was a mutant for DNA ligase, Okazaki fragments would not be joined on the lagging strand.

2. Hence, on the leading strand high molecular weight fragments would form.

3. On the lagging strand low molecular weight fragments would form.

4. Which concludes option ‘a’ is correct.