Final answer:
Enantiomers are mirror images of each other and can rotate the plane of polarized light. Diastereomers have different physical and chemical properties. Assigning R or S to a chiral center depends on the orientation of the groups attached to it.
Step-by-step explanation:
Enantiomers are molecules that share overall structure and bonding patterns, but differ in how the atoms are three dimensionally placed such that they are mirror images of each other. They are also called optical isomers because they can rotate the plane of polarized light. Diastereomers, on the other hand, have different physical and chemical properties than their counterparts.
When assigning R or S to a chiral center, if the lowest priority group is pointing away from the viewer, R (rectus) is assigned if an arrow drawn from the highest to the second highest to the third highest priority group is clockwise or directed to the right. If it is directed to the left or counterclockwise, S (sinister) is assigned. If the lowest priority group is not pointing away from the viewer, a different naming system is used.
Enantiomers and diastereomers often have very different biological properties and activities, and this is important to consider in drug treatment. Additionally, certain species of microorganisms can only metabolize one type of optical isomer, making it necessary to be aware of their presence.