BIOMOLECULES AND ENZYMES

Detailed explanation-1: -All amino acids except glycine are optically active and rotate plane polarised light to the left. They are laevorotatory.

Detailed explanation-2: -Both stereoisomers of amino acids occur in nature, but only L amino acids are produced and used in cells. They are also the only stereoisomer to be incorporated into peptides during translation. In this regard, only L amino acids are ‘biologically active’.

Detailed explanation-3: -Amino acids, the building blocks of peptides and proteins, are found naturally in two forms (L and D enantiomers), except for glycine which does not have a chiral center.

Detailed explanation-4: -All amino acids except for glycine are stereoisomers. This means that there are mirror images of their structure. It is just like how we have left hands and right hands. These are labeled L (left-handed) and D (right-handed) to distinguish the mirror images.