1. The 2'-hydroxyl group:
* RNA: RNA has a hydroxyl group (OH) attached to the 2' carbon of its ribose sugar. This hydroxyl group makes RNA more susceptible to hydrolysis, a process where the phosphodiester bonds connecting nucleotides are broken down by water. In alkaline conditions, this hydrolysis reaction is accelerated.
* DNA: DNA lacks this 2'-hydroxyl group, having only a hydrogen atom (H) at that position on its deoxyribose sugar. This makes DNA significantly more resistant to hydrolysis in alkaline environments.
2. Base structure and degradation:
* RNA: The presence of uracil (U) in RNA makes it prone to deamination, where the amino group (-NH2) on uracil is converted to a carbonyl group (C=O). This converts uracil to cytosine (C), potentially leading to mutations. While deamination can happen to both RNA and DNA, it's more prevalent in RNA due to the presence of uracil.
* DNA: DNA contains thymine (T) instead of uracil. Thymine is less prone to deamination than uracil, contributing to the greater stability of DNA.
3. Secondary structures:
* RNA: RNA's single-stranded nature allows it to form a variety of complex secondary structures, including hairpin loops, stem-loops, and pseudoknots. These structures can be quite fragile and can be disrupted by alkaline conditions, further contributing to RNA degradation.
* DNA: DNA's double-stranded structure, with its hydrogen bonds between complementary bases, provides greater stability and resistance to alkaline disruption.
In summary:
The presence of the 2'-hydroxyl group, the inherent instability of uracil, and the more complex and fragile secondary structures make RNA much more vulnerable to degradation in alkaline conditions compared to DNA.
