Biology 10th Edition by Eldra Solomon,Charles Martin,Diana Martin,Linda Berg

Exercise 17

EVOLUTION LINK. Each amino acid could potentially exist as one of two possible enantiomers, known as the d-form and the l-form (based on the arrangement of the groups attached to the asymmetric a carbon). However, in all organisms, only l-amino acids are found in proteins. What does this suggest about the evolution of proteins?