Answer: Sequence of amino acids in the polypeptide chain.
- A Sequence of amino acids in the polypeptide chain
- B The regular coiling pattern formed by hydrogen bonds along the backbone
- C The regular pleated pattern formed between adjacent backbone strands
- D The overall compact 3D shape stabilised by multiple bond types
Correct answer: A. Sequence of amino acids in the polypeptide chain
Explanation: Primary structure is the linear sequence of amino acids linked by peptide bonds.
Two amino acids join via a condensation reaction: the carboxyl -OH of one and an amine -H of the other are eliminated as water, leaving a peptide bond (-CO-NH-) linking them into a dipeptide; repeating this builds a full protein chain.
Concept context
The chemistry of life: carbohydrates, proteins, lipids, nucleic acids, enzymes, and vitamins. Understand their structures, classification, and biological functions. Highly relevant for NEET and Class 12 board exams.