what are the functions of the nucleus?
The nucleus is the centre for cellular organisation. It contains, in eukaryotes, the genome of the organism; i.e. it is where DNA is found. It is the site of coordination of several molecular processes and as a result, any decisions (speaking in broad terms) would have to be made by it. For instance, if a plant cell is in a condition where there is a repellent chemical, receptors on the plasma membrane will signal this situation through cytoplasmic signalling pathways to the nucleus, where genes whose products regulate the the movement of the cell away from that chemical. Thereofre, everything a cell does is pretty much governed by the nucleus. Here I want you to note that it is not only in the nucles DNA is found; it is also in the chloroplasts and the mitochondria. However, the nuclear genome is the one that plays a much larger role in cell growth, development, survival and differentiation.