What is the primary role of proto-oncogenes?

Proto-oncogenes play a crucial role in the regulation of cell growth and division. They are normal genes that, when mutated or expressed at high levels, can become oncogenes and contribute to the development of cancer. The primary function of proto-oncogenes is to promote pathways that lead to cell proliferation and survival. They encode proteins that are involved in signaling pathways, which ultimately regulate various processes such as the cell cycle, differentiation, and apoptosis (programmed cell death).

When proto-oncogenes are functioning properly, they help ensure that cells divide at a controlled rate, allowing for normal growth and tissue maintenance. If these genes become altered, they can lead to unregulated cell division, which is a hallmark of cancer. This highlights their importance in maintaining normal cellular functions and how their dysregulation can have serious consequences for the organism.

In contrast, the other options relate to different functions that do not align with the primary role of proto-oncogenes. For instance, the roles of inhibiting cell growth and promoting cell death are associated more with tumor suppressor genes, while maintaining chromosome structure involves proteins that stabilize and manage DNA rather than regulating cell division directly.