Question

The three-dimensional shape of a protein is determined by the primary, secondary, tertiary, and in many cases, the quaternary structure of the protein. The following sentence is taken from scientific articles on protein structure. Choose the level of protein structure that applies best to the sentence.

There are hydrogen bonds between polar amino acid R groups within a polypeptide.

Answer 1

The statement refers to the tertiary structure of a protein, which is characterized by the three-dimensional folding and includes hydrogen bonding between polar R groups of amino acids.

Step-by-step explanation:

Protein Structure and Bonds

The sentence 'There are hydrogen bonds between polar amino acid R groups within a polypeptide' best describes the tertiary structure of a protein. The tertiary structure is the large-scale three-dimensional shape of a single polypeptide chain. It is determined by interactions like hydrogen bonds between the R groups (side chains) of amino acids that are far apart in the primary sequence, but brought close together as the chain folds. This level of protein structure can include various types of bonding beyond hydrogen bonds, like ionic bonds, disulfide bridges, and hydrophobic interactions between nonpolar side chains.

The secondary structure, on the other hand, involves hydrogen bonds between backbone atoms in the polypeptide chain resulting in alpha-helices and beta-pleated sheets, while the quaternary structure involves interactions between multiple polypeptide subunits.