Thymine vs Uracil: DNA Stability — NEET Biology

Which of the following statements correctly identify reasons contributing to DNA being chemically more stable than RNA? S1: The absence of a 2'-hydroxyl group in the deoxyribose sugar of DNA makes its phosphodiester backbone less susceptible to hydrolysis and thus more stable. S2: The presence of thymine (5-methyl uracil) in DNA instead of uracil confers additional chemical stability, as thymine is less prone to deamination reactions than uracil. S3: DNA's double-stranded helical structure provides a physical shield for the bases, making them less accessible to chemical mutagens and enzymatic degradation. S4: The complementary base pairing within DNA's double helix allows for efficient repair mechanisms, contributing to its overall genetic stability by correcting mutations. S5: While DNA is generally more stable, the occasional presence of uracil in DNA (through deamination of cytosine) can be easily repaired due to its single-stranded nature.