Question

DNA contains nucleobases, sugar and phosphate. Re of which among these from a DNA sample will significantly affect the length of the DNA?

• A. Nucleobases
• B. Sugar
• C. Phosphate
• D. None of these

Answer 1

Answer: (A)

Removal of nucleobases from DNA will not significantly affect the length of DNA because the backbone of DNA strand is made up of deoxyribose sugar and phosphoric acid group. The phosphate group is connected to carbon $5^{{}^{\prime }}$ of the sugar residue of its own nucleotide and carbon $3^{{}^{\prime }}$ of the sugar residue of the next nucleotide by $\left(3^{{}^{\prime }}-5^{\prime }\right)$ phosphodiester bonds. If we remove phosphate group or sugar, it will reduce the length of backbone and hence the length of DNA also. But removal of nitrogenous base will have no effect on the length of DNA.