Abstract DBI 9750048 D. Scott Baskerville This action funds an NSF/Alfred P. Sloan Postdoctoral Research Fellowship in Molecular Evolution for 1997. These fellowships support studies involving the theoretical, comparative, computational, and/or experimental analyses of biological patterns and processes at the molecular level within the framework of organismic evolutionary change and adaptation. These studies also include the use of molecular data to address broader evolutionary questions. Each fellowship supports a research and training plan to be carried out in a sponsmring laboratory. The research and training plan for this fellowship is entitled "Examining the origins of enzymes." Most chemical reactions in living systems are know to be catalyzed by protein enzymes but a few have been shown to be catalyzed by RNA or RNA-protein enzymes. By comparing the abilities of synthetic protein, RNA, and RNA-protein to give rise to new enzymes, this research addresses the possibility that RNA enzymes emerged more readily and were later supplanted by proteins during evolution.