The number of chiral centres present in threonine is ________. — Biomolecules Chemistry Question

💡 Solution & Explanation

**Step 1: Identify the structure of threonine.** Threonine is an amino acid with the molecular structure: CH₃-CH(OH)-CH(NH₂)-COOH **Step 2: Define a chiral centre.** A chiral centre (stereogenic centre) is a carbon atom bonded to four different groups. **Step 3: Analyze the first potential chiral centre.** The carbon in the CH₃ group is bonded to three hydrogen atoms and one carbon—not four different groups. Not chiral. **Step 4: Analyze the second potential chiral centre.** The carbon in CH(OH) is bonded to: - CH₃ group - OH group - H atom - CH(NH₂)COOH group These are four different groups. **This is a chiral centre.** **Step 5: Analyze the third potential chiral centre.** The carbon in CH(NH₂) is bonded to: - NH₂ group - COOH group - H atom - CH(OH)CH₃ group These are four different groups. **This is a chiral centre.** **Step 6: Count total chiral centres.** Threonine has 2 chiral centres (the carbons bearing the OH and NH₂ groups). Therefore, the answer is **2.00**.