In terms of protein structure, what is a secondary structure, and which molecular bonds or interactions contribute to stabilizing this level of structure?

True or False: Globular proteins, unlike fibrous proteins, are water-insoluble and composed of compact, non-repeating structures.

True or false: In the β-sheet in the figure below, covalent bonding between specific atoms is the type of bonding responsible for the sheet formation.

A protein has the primary structure Thr-His- Pro-Tyr-Pro-Leu-Pro-Pro -Glu-Thr. Which amino acid is responsible for its very kinked helix secondary structure?

Which of the following statements about protein primary and secondary structures are correct?

I. The primary structure of a protein refers to the linear sequence of amino acids in the polypeptide chain.

II. The secondary structure of a protein is stabilized by hydrogen bonds between side chains of amino acids.

III. The alpha helix and beta sheet are types of secondary structures in proteins.

IV. Secondary structures such as alpha helices and beta sheets are formed through interactions between the R groups of amino acids.

Which of the following statements about α helices and β−pleated sheets in protein secondary structures are correct?

I. Alpha helices are stabilized by hydrogen bonds between the carbonyl oxygen of one amino acid and the amide hydrogen of an amino acid four residues earlier.

II. Beta-pleated sheets are formed by hydrogen bonding between the side chains of amino acids in adjacent beta strands.

III. Alpha helices are typically right-handed spirals, while beta-pleated sheets can be arranged in parallel or antiparallel orientations.

IV. The beta-pleated sheet structure involves interactions between backbone amide hydrogens and carbonyl oxygens of adjacent beta strands.

Which of the following statements correctly describes the main secondary structural feature of collagen?