TAMU BIOL111 Exam 1 Practice Exam

Enantiomers are a specific type of stereoisomer characterized by their unique relationship of being mirror images of one another. This means that while two enantiomers have the same molecular formula and structural formula, they differ in the three-dimensional arrangement of atoms in space. This property is critical because enantiomers can exhibit significantly different biological activities, as observed in many pharmaceuticals where one enantiomer may be therapeutically beneficial while the other could be ineffective or harmful. The defining characteristic of enantiomers is the presence of chiral centers—typically carbon atoms that are bonded to four different substituents—leading to non-superimposable images, similar to left and right hands. This feature distinguishes them from other types of isomers, such as structural isomers, which differ in the connectivity of their atoms, or cis/trans isomers, which have different arrangements in space but are not mirror images.