Answer: Watson and Crick.
- A Watson and Crick
- B Pauling and Corey
- C Chargaff
- D Rosalind Franklin
Correct answer: A. Watson and Crick
Explanation: Watson and Crick proposed the double helix model of DNA in 1953.
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.