So someone asked this question in my MCAT review class and I don't have an answer...wonder if anyone has any thoughts. It's tough to explain without drawing, but I'll try. Say you have a center carbon with 4 groups bonded and you are trying to figure out if that carbon is chiral, and if it is, whether the absolute configuration is R or S. Here are the four groups. One is a Hydrogen. One is an -OH. The other two are alkene groups, geometric isomers of one another, as in they are the same molecule but one is E and the other is Z. Is that center carbon chiral? If so, which alkene gets the higher priority - E or Z? Another variation on that same thought. What if the two groups (besides the H and OH) were chiral carbons themselves...idential except one group is R and the other is S? Now is the center carbon chiral? Is it R or S? I think these questions are beyond the scope of anything one would see on the MCAT, but thought provoking just the same.