Protein Structure: Primary to Tertiary — NEET Biology
✅ Asked in NEET 2026Alpha-helix is found in which level of protein structure?
Alpha-helix is found in which level of protein structure?
Answer & NCERT explanation
Correct answer: A — Secondary structure
The alpha-helix is a feature of the secondary structure of proteins, formed by right-handed coiling of the polypeptide chain stabilised by hydrogen bonds.
Read more NCERT concept on the PYQ
The first amino acid is also called as N-terminal amino acid. The last amino acid is called the C-terminal amino acid. A protein thread does not exist throughout as an extended rigid rod. The thread is folded in the form of a helix (similar to a revolving staircase). Of course, only some portions of the protein thread are arranged in the form of a helix. In proteins, only right handed helices are observed. Other regions of the protein thread are folded into other forms in what is called the secondary structure. In addition, the long protein chain is also folded upon itself like a hollow woolen ball, giving rise to the tertiary structure. This gives us a 3-dimensional view of a protein. Tertiary structure is absolutely necessary for the many biological activities of proteins.
NEET tests your understanding of protein structure levels, especially that proteins fold into secondary structures (like alpha helices) and tertiary structures (3D globular form). Students commonly confuse secondary and tertiary structures or forget that only right-handed helices occur in proteins. The key trap: thinking a protein's primary structure alone determines its function—you must remember that tertiary structure (3D folding) is essential for biological activity. To score well: distinguish that secondary structure is local folding (helix/sheet), while tertiary structure is the entire chain folding into a 3D shape, and this 3D form is crucial for protein function and enzyme activity.
What does NCERT say about first amino acid also?
Has this concept appeared in NEET?
Which chapter is this from?
Through deep analysis of NEET and NTA, 88 of 90 questions from the NEET 2026 paper were matched straight from the MedicNEET Biology question bank.
88/90MedicNEET's Biology question bank is built from the same NCERT lines NTA picks repeatedly. Not random MCQs — questions crafted exactly like NTA crafts them.