Final answer:
Proto-oncogenes promote cell division through growth factor receptors, while tumor suppressor genes inhibit it by indicating DNA problems or excessive cellular density.
Step-by-step explanation:
Cell division is regulated by two major genes. Proto-oncogenes stimulate cell division and tumor suppressor genes inhibit cell division. Proto-oncogenes code for proteins like growth factor receptors that promote DNA replication and cell division.
Tumor suppressor genes produce proteins that signal cell cycle issues or cellular density, thus inhibiting unnecessary or abnormal cell division. This mechanism is crucial for preventing conditions such as cancer, where cell division becomes uncontrolled.