Final answer:
Protein secondary structures like α-helices and β-sheets are defined by hydrogen bonds forming between the N-H and C=O groups within the polypeptide backbone, not the side chains or specific short amino acid sequences.
Step-by-step explanation:
The secondary structures of proteins, such as the α-helix and β-pleated sheet, are defined by regular folding patterns that result from hydrogen bonding. However, it is not the amino acid side chains that determine these structures, but rather the hydrogen bonds forming between the N-H group of one amino acid and the C=O group of another amino acid that is typically four residues away in the polypeptide backbone. It is incorrect to assert that a certain short amino acid sequence will always adopt the same secondary structure or that only a few specific sequences can form these structures; instead, the secondary structure adopted by a particular sequence depends on the entire polypeptide context and not just the local sequence.
Therefore, the statement that most accurately defines the formation and stabilization of protein secondary structures is option 4: 'The folding patterns result from hydrogen-bonding between the N-H and C=O groups in the polypeptide backbone.' This explanation acknowledges the type of bonding responsible for the characteristic shapes of the α-helices and β-sheets, which are crucial for the overall three-dimensional structure and function of proteins.