OBJECTIVE LIFE SCIENCE
MOLECULAR BIOLOGY
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
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3’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
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5’-phosphate group of one nucleotide unit is joined to the 5’-hydroxyl group of the next nucleotide
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3’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide
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Detailed explanation-1: -Two successive nucleotides of DNA are joined by phosphodiester linkage in which the 5’-phosphate group of one nucleotide unit is joined to the 3’-hydroxyl group of the next nucleotide. Thus, phosphate and pentose sugars of DNA are joined by phosphodiester linkage; the correct answer is B.
Detailed explanation-2: -The phosphate group attached to the 5’ end of one nucleotide and the hydroxyl group at the 3’ end of another nucleotide have the potential to form phospodiester bonds, and hence link adjacent nucleotides. This linkage provides the sugar-phosphate backbone that gives DNA its structural rigidity.
Detailed explanation-3: -DNA is a polymer of nucleotides which are linked to each other by 3-5 phosphodiester bond.
Detailed explanation-4: -The phosphate is attached to the 5’ carbon. The 3’ carbon of one sugar is bonded to the 5’ phosphate of the adjacent sugar. Specifically, the phosphodiester bond links the 3’ carbon atom of one sugar molecule and the 5’ carbon atom of another (hence the name, 3’, 5’ phosphodiester linkage).