Genes are located in the nucleus of a cell. But which structures in a cell are they ON?

Scientists discover two populations of mice on either side of a major river. the two populations have almost identical genes but the mice from one side cannot breed with mice from the other. this is most likely because

Which of the following is the earliest era of earth's geologic time scale? cenozoic mesozoic precambrian paleozoic

According to theories of how life began, how did early organic molecules begin to separate from the outside world? a: specialized enzymes were required b: chains of amino acids created a barrier c: formation of microspheres or vesicles d: rna catalyzed the formation of membranes