Which of the following satements is correct ?

Options

A. All amino acids are optically active
B. All amino acids except glycine are optically active.
C. All amino acids except glutamic acid are optically active
D. All amino acids except lysine are optically active

Answer

To determine which statement is correct regarding the optical activity of amino acids, we need to analyze each option provided:

1. **All amino acids are optically active.**
- This statement is incorrect. Not all amino acids are optically active. The amino acid glycine is the only one that is not optically active because it has two hydrogen atoms attached to its alpha carbon, making it achiral.

2. **All amino acids except glycine are optically active.**
- This statement is correct. All amino acids, except glycine, have a chiral center at the alpha carbon, which allows them to exist in two enantiomeric forms (D and L forms), making them optically active.

3. **All amino acids except glutamic acid are optically active.**
- This statement is incorrect. Glutamic acid is also optically active, as it has a chiral center at its alpha carbon. Therefore, this statement does not hold true.

After analyzing the statements, we conclude that the correct answer is:

**All amino acids except glycine are optically active.**