How is the structure of $\mathrm{RNA}$ different from the structure of $\mathrm{DNA}$?

• A. $\mathrm{RNA}$ contains uracil instead of thymine.
• B. $\mathrm{RNA}$ has a deoxyribose sugar, whereas $\mathrm{DNA}$ has a ribose sugar.
• C. $\mathrm{RNA}$ is more stable than $\mathrm{DNA}$ due to its double helix structure.
• D. $\mathrm{RNA}$ is double-stranded while $\mathrm{DNA}$ is single-stranded.

Answer: (A)

Verified step by step guidance

1. Begin by understanding the basic structural components of nucleic acids: both DNA and RNA are composed of nucleotides, which include a sugar, a phosphate group, and a nitrogenous base.
2. Identify the sugar component: DNA contains deoxyribose sugar, while RNA contains ribose sugar. The difference is that ribose has an additional hydroxyl group (-OH) at the 2' position, which deoxyribose lacks.
3. Examine the nitrogenous bases: DNA includes adenine (A), thymine (T), cytosine (C), and guanine (G). RNA includes adenine (A), uracil (U), cytosine (C), and guanine (G). Note that RNA uses uracil instead of thymine.
4. Consider the structural form: DNA is typically double-stranded, forming a double helix structure, whereas RNA is usually single-stranded. This structural difference affects their stability and function.
5. Clarify the stability aspect: DNA's double helix structure provides stability, whereas RNA's single-stranded nature makes it less stable. However, RNA can form secondary structures like hairpins and loops that contribute to its functional versatility.