In the secondary structure of proteins, hydrogen bonds between amino acids create: A Side groups B Alpha helixes and beta -pleated sheets C Disulfide bridges D Van der waals interactions E All of the above

The correct answer is **B. Alpha helices and beta-pleated sheets.**<br /><br />Here's why:<br /><br />* **Secondary structure** refers to local folded structures that form within a polypeptide due to interactions between atoms of the backbone. The most common secondary structures are alpha-helices and beta-pleated sheets. These structures are held together by hydrogen bonds between the carbonyl oxygen of one amino acid and the amide hydrogen of another amino acid further down the chain.<br /><br />* **Side groups (A)** are involved in tertiary structure, where interactions between the R-groups of amino acids determine the overall 3D shape of the protein.<br /><br />* **Disulfide bridges (C)** are also part of tertiary structure. They are covalent bonds between cysteine residues.<br /><br />* **Van der Waals interactions (D)** contribute to both tertiary and quaternary structure. They are weak attractions between atoms.<br /><br />* **E** is incorrect because only B is directly related to the hydrogen bonding in secondary structure.<br />