Final answer:
Injecting G2 arrested frog oocytes with cytoplasm from an M phase donor cell induces the oocytes to enter meiosis, showing the effect of the maturation promoting factor (MPF), a key protein kinase in cell cycle regulation.
Step-by-step explanation:
When G2 arrested frog oocytes were injected with cytoplasm from an M phase donor cell, the oocytes were induced to enter meiosis. This experiment demonstrates the presence of a maturation promoting factor (MPF), which is responsible for the transition from G2 phase to M phase in the cell cycle. MPF is a protein kinase that consists of two subunits, and it plays a crucial role in the regulation of the cell cycle by inducing the breakdown of the nuclear membrane, chromosome condensation, and entry into meiosis. The results of such an experiment provided insights into the mechanisms that control cell division and helped to further our understanding of the developmental processes that occur both before and after fertilization, leading to the formation of a zygote.