Question

The introduction to this chapter, which describes the sequencing of 4000-year-old DNA, emphasizes DNA’s extreme stability. What aspects of DNA’s structure contribute to the stability of the molecule? Why is RNA less stable than DNA?

Answer 1

Answer:

DNA is more stable than RNA due to the absence of a hydroxyl group in the 2' position of the deoxyribose sugar.

Explanation:

• Each RNA or ribonucleic acid molecule is composed of a pentose sugar called Ribose, a  phosphate group and a nitrogenous base.
• A RNA chain is made up of a ribose phosphate backbone linked by phosphodiester bonds.
• The Ribose sugar has a hydroxyl group in the 2' position.
• This hydroxyl group is susceptible to hydrolysis in presence of alkaline condition.
• This hydrolysis causes the breakdown of the phosphodiester linkage between the phosphate group and the ribose sugar, causing the disruption of the entire RNA structure.
• Each DNA or deoxyribonucleic acid is composed of a pentose sugar called Deoxyribose, a phosphate group and a nitrogenous base.
• A DNA chain is made up of a deoxyribose  phosphate backbone linked by phosphodiester bonds.
• In the Deoxyribose sugar, the 2' hydroxyl group is absent and hence it is no longer susceptible to hydrolysis under alkaline conditions.
• Hence, DNA is more stable than RNA.