Final answer:
Both DNA and RNA have a phosphate-sugar backbone. DNA contains deoxyribose and is double-stranded, whereas RNA contains ribose and is single-stranded. RNA's primary role is in protein synthesis, as opposed to DNA's role in storing genetic information.
Step-by-step explanation:
The structural similarity between DNA and RNA that is most accurate is that both DNA and RNA have a phosphate-sugar backbone. While it's true that they both contain nucleotides which include a phosphate group, a pentose sugar, and a nitrogenous base, there are significant differences. DNA contains deoxyribose sugar and is double-stranded, forming a double helix. On the other hand, RNA contains ribose sugar and is single-stranded. The four nitrogenous bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T), but in RNA, uracil (U) replaces thymine.
Furthermore, while DNA is the repository of genetic information in cells, RNA plays a key role in protein synthesis and its regulation. RNA molecules like messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA) are crucial in translating the genetic code into proteins. This is different from storing genetic information, which is the primary role of DNA.