Final answer:
The structural feature shared by DNA, RNA, and proteins is phosphodiester bonds. Nucleotides in DNA and RNA are connected by these bonds, which are part of the sugar-phosphate backbone. Proteins, while comprised of amino acids linked by peptide bonds, do not have phosphodiester bonds.
Step-by-step explanation:
The structural feature shared by DNA, RNA, and proteins is phosphodiester bonds. Both DNA and RNA are made up of units called nucleotides, which are joined together by these bonds. Proteins, on the other hand, are made up of amino acids. However, the presence of phosphodiester bonds is unique to the nucleic acids DNA and RNA; proteins do not have them. Instead, proteins have peptide bonds between amino acids.
Nucleotides, which are the building blocks of nucleic acids, consist of a phosphate group, a pentose sugar, and a nitrogen-containing base. Nucleotides in a single strand of nucleic acid are linked by phosphodiester bonds between the 5' phosphate group of one nucleotide and the 3' hydroxyl group of another. This connection forms the sugar-phosphate backbone of DNA and RNA. While hydrogen bonds are important for the secondary structure, such as in the DNA double helix where they hold the two strands together by connecting complementary bases, they are also found in the tertiary structure of proteins. Therefore, the correct answer to the question is phosphodiester bonds.