Question

DNA is a polymer of nucleotides which are linked to each other by 3-5 phosphodiester bonds. To prevent polymerisation of nucleotides, which of the following modifications would you choose?
A)Replace purines with pyrimidines
B)Remove/replace 3-OH group in deoxyribose
C)Remove/replace 2-OH group with some other group in deoxyribose
D)Both B and C.

Answer 1

Hint: Phosphodiester bond is the basis of all living forms on earth. It is the bond formed between nucleotides. In this the bond is formed between the sugar group of one nucleotide with the phosphate group of the other.

Complete answer:
To solve this question, we must know about the structure of DNA.
The DNA is made up of deoxyribose sugar, phosphate backbone and nucleotides. The deoxyribose sugar has one oxygen less in the hydroxyl group present in the ribose sugar. This makes DNA more stable than RNA.

In DNA, the nucleotides are linked together with 3-5 phosphodiester bonds. It is formed in between phosphate molecules of one nucleotide with the two sugar molecules of the other to form a polymer.

If the purines are replaced by pyrimidines, then also the bond will be formed between 3-OH and the phosphate of the other nucleotide. Thus, option A is incorrect.

If the 3-OH group from the sugar backbone of DNA then the phosphate of the nucleotide will not be able to make bond with the other nucleotide. Thus, the polymerisation can be prevented.

The 2-OH group do not play any role in bond formation. At 2’ position, the oxygen group is absent. So, it cannot form phosphodiester bonds. Thus, option C is incorrect.

Hence, the correct answer is option (B)

Note: The phosphodiester bond helps in maintaining the structure and integrity of DNA and RNA. The enzyme DNA polymerase helps in forming the phosphodiester bond. One turn of DNA has 18 phosphodiester bonds.