Question

Explain how the cell cycle is regulated.

Answer 1

The cell cycle is regulated by checkpoints monitored by regulatory proteins, including cyclins and Cdks, that either advance the cell or halt the progression based on internal and external conditions.

Step-by-step explanation:

How the Cell Cycle is Regulated

The regulation of the cell cycle is a highly orchestrated process involving internal and external controls, known as checkpoints. These checkpoints are strategically positioned at different phases, such as at the end of G1, at the G2/M transition, and during metaphase. The mechanisms of control include regulatory proteins that either signal the cell to proceed or halt the cycle. Among these proteins, cyclins and cyclin-dependent kinases (Cdks) act as positive regulators that advance the cell cycle, whereas negative regulators, like tumor suppressor proteins, ensure conditions are favorable before continuing. Growth factors also influence the regulation by triggering cell division externally. Misregulation of these controls can lead to uncontrolled cell division, a hallmark of cancer.

Checkpoints monitor and control the progression through the cell cycle.

Cyclins and Cdks are key molecules in pushing the cycle forward.

Negative regulators prevent the cycle from advancing under unfavorable conditions.

Answer 2

Cell-division control affects many aspects of development. Caenorhabditis elegans cell-cycle genes have been identified over the past decade, including at least two distinct Cyclin-Dependent Kinases (CDKs), their cyclin partners, positive and negative regulators, and downstream targets. The balance between CDK activation and inactivation determines whether cells proceed through G1 into S phase, and from G2 to M, through regulatory mechanisms that are conserved in more complex eukaryotes.

This is the required process through phosphorylation, Cdks signal the cell that it is ready to pass into the next stage of the cell cycle. As their name suggests, Cyclin-Dependent Protein Kinases are dependent on cyclins, another class of regulatory proteins. Cyclins bind to Cdks, activating the Cdks to phosphorylate other molecules.