What distinguishes DNA from RNA in terms of sugar structure?

The distinction between DNA and RNA regarding their sugar structure lies primarily in the presence of specific functional groups on the sugar component of each nucleic acid. In DNA, the sugar is deoxyribose, which is characterized by the absence of an -OH (hydroxyl) group at the 2' carbon atom; instead, it has an -H (hydrogen) atom. This is what gives deoxyribose its name, as it is a ribose sugar that has lost an oxygen atom at the 2' position.

In contrast, RNA contains ribose as its sugar, which has an -OH group attached to the 2' carbon. This difference in sugar structure is crucial because it influences the stability and function of the two types of nucleic acids. RNA is generally more reactive and less stable than DNA due to the presence of the -OH group, rendering it more suitable for its role in protein synthesis and regulation.

Therefore, the assertion that the sugar in DNA has an H attached at the number 2 carbon correctly highlights the fundamental distinction in the sugar composition between DNA and RNA, with significant implications for their biological roles.