What regulates the cell cycle?

The regulation of the cell cycle is a complex process that involves various mechanisms to ensure that cells divide accurately and at the right time. One of the central components in this regulation is the role of specific proteins and enzymes, which can be classified as chemicals inside the cell. These include cyclins and cyclin-dependent kinases (CDKs), which act together to control the progression of the cell cycle through different phases: G1, S, G2, and M. These proteins are responsible for initiating the various processes needed for cell division, such as DNA replication and mitosis.

Cell cycle checkpoints, which are critical for monitoring the integrity of the cell's DNA and ensuring that conditions are favorable for division, supplement the internal chemical signals. They detect issues such as DNA damage or incomplete replication and can halt the cycle until the problems are resolved. While external environmental factors and RNA molecules might influence cellular processes, the direct regulators of the cell cycle's timing and progression are primarily the internal chemical signals, specifically proteins that have a direct impact on the cell cycle machinery. Thus, chemicals inside the cell, primarily the regulatory proteins like cyclins and CDKs, are at the core of cell cycle regulation.