Answer: Configuration of the lowest chiral carbon.
- A Number of hydroxyl groups present
- B Direction of rotation of polarised light
- C Position of the carbonyl in the chain
- D Configuration of the lowest chiral carbon
Correct answer: D. Configuration of the lowest chiral carbon
Explanation: D or L refers to the configuration of the lowest-numbered chiral carbon (the one farthest from the carbonyl), compared with glyceraldehyde. It is not related to the sign of optical rotation.
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.