  The modest answer to the question ‘What do genes do?’ is that they “code for” or “determine” the linear sequences in RNA molecules and polypeptides synthesized in the cell. (Even this modest answer needs to be qualified because RNA molecules are often spliced and edited in ways that affect the linear sequence of amino acids in the eventual polypeptide product.) But biologists have offered a far less modest answer as well. The bolder answer is part of a sweeping, fundamental theory. According to this theory, genes are “fundamental” entities that “direct” the development and functioning of organisms by “producing” proteins that in turn regulate all the important cellular processes. It is often claimed that genes provide “the information”, “the blueprint”, or “the program” for an organism. It is useful to distinguish this sweeping, fundamental theory about the allegedly fundamental role of genes from the modest, basic theory about what genes do with respect to the synthesis of RNA and polypeptides.