assignment A student has two DNA molecules, A and B, to be used in a synthesis r

Question

assignment

A student has two DNA molecules, A and B, to be used in a synthesis reaction (polymerization) of new DNA. The molecules are individually incubated with DNA polymerase in the presence of all necessary components.
a. Explain why only one of these two DNA molecules will give rise to synthesis of new DNA, and outline the structure of the product formed.

Molecular A: 5 '--- AATCCTTAAGCCGCCAGTTCGGCTGGCGGC --- 3'
Molecular B: 5 '--- CGGCGGTCGGCTTGACCGCCGAATTCCTAA --- 3'

b. The student now wishes to detect the DNA radioactively with 32P during the synthesis reaction, and therefore adds deoxynucleotides that are radioactively labeled on either the or phosphate. Explain why only radioactive DNA is formed using one of these two deoxynucleotides ( or )?

Explanation / Answer

DNA A and B both are same sequence but differ only in the orientation 5' to 3'. The primer for DNA A is
different from DNA B and DNA polymerase binds to 3' ends of the DNA. So DNA polymerase not binds same sequence in diffferent orientation.
5 '--- AATCCTTAAGCCGCCAGTTCGGCTGGCGGC --- 3'
3' --- TTAGGAATTCGGCGGTCAAGCCGACCGCCG --- 5'

B. Alpha deoxynucleotides are used in the experiments. Because during replication the deoxynucleotides of beta and gamma phosphates released from nucleotides, only alpha phosphate involved in the diester phosphate bonding in replcation.

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