THE SPERM IS MOBILE WHILE THE EGG WEIGHTS (PUN INTENDED)

Sperm are usually the mobile gamete (reproductive cell of either sperm or egg).  They are designed to quickly deliver the genes contributed by the father.  As, such they are fast and mobile.  Their cells contain genes and the machinery for movement.  Little else weighs them down.  Eggs on the other hand are often immobile and contain the genes of the mother and all other supplies for life.  As such, it is the egg and therefore the mother that contributes machinery such as mitochondria, Golgi apparatus, and all the other goodies distributed within the cytoplasm.  As it turns out, the mitochondria have its own genetic information (DNA = deoxyribose nucleic acid) allowing the lineage of the mother to be traced.  Interesting that we carry a maternal marker within our cells.