Question
Alpha-helix is found in which level of protein structure ?
This question was previously asked in
NEET UG Re-Exam 2026 Question Paper (21-Jun-2026)
The correct answer is
Secondary structure
Protein Structure Levels & Alpha-Helix
Proteins fold into specific three-dimensional shapes, organized into four structural levels:
- Primary Structure: The linear sequence of amino acids.
- Secondary Structure: Localized, repeating folding patterns like alpha-helices and beta-sheets, stabilized by hydrogen bonds between backbone atoms.
- Tertiary Structure: The overall 3D conformation of a single polypeptide chain.
- Quaternary Structure: The assembly of multiple polypeptide chains.
Alpha-Helix Formation
The alpha-helix is a common motif characterized by its helical shape. This structure arises from hydrogen bonding between the carbonyl oxygen of one amino acid residue and the amide hydrogen of the amino acid residue four positions earlier in the polypeptide chain. These regular, repeating local folding patterns are hallmarks of protein secondary structure.
Therefore, the alpha-helix is found in the secondary structure level of protein organization.
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