This paper will consider how the account of weak emergence presented by Wilson in the book Metaphysical emergence (2021) can be used to explore the relation between biochemical functions and chemical structure in biochemical molecules, as vitamin B12. The structure of the paper is the following. Section 2 will introduce why biochemical functions are interesting from a philosophical perspective and why their relation to molecular structure can be seen as problematic. In doing so, it will consider the definition of biochemical functions as in Bellazzi (2022) for which they can be seen as sets of chemical dispositional properties that contribute to biological processes. Section 3 will explore how, given this definition of biochemical functions, we can interpret the relation between chemical structure and biochemical structure via weak emergence. Section 4 concludes.