The word chiral derives from the Greek word ceir (cheir), meaning hand. Our hands are chiral – the right hand is a mirror image of the left – as are most of life’s molecules such as (R)-alanine and (S)-alanine, which are mirror images of each other.
In our cells we find only one form of this amino acid, (S)-alanine. The same is true for enzymes, antibodies, hormones and DNA.