The p53 enzyme system prevents progression to which stage of the cell cycle?
choices are:
1. G1
2.Cytokineses
3.S phase
4. Mitosis
5. G2
* I think it's S phase, It's not G1 right?
This should explain it. It's not the S phase, from this explanation.
http://www.khanacademy.org/science/biology/cellular-molecular-biology/stem-cells-and-cancer/a/cell-cycle-regulators
To determine which stage of the cell cycle the p53 enzyme system prevents progression to, we need to understand the function of the p53 protein. The p53 protein plays a crucial role in regulating the cell cycle and preventing the propagation of damaged DNA.
In response to DNA damage or other cellular stress, p53 is activated and acts as a transcription factor, initiating several cellular responses, including cell cycle arrest, DNA repair, or programmed cell death (apoptosis). This activation of p53 can occur at various stages of the cell cycle, depending on the type and extent of the damage.
Among the given choices, the p53 enzyme system primarily prevents progression to the G1 (Gap 1) stage of the cell cycle. In normal circumstances, p53 monitors the integrity of the DNA during the G1 phase. If DNA damage is detected, p53 halts progression to the S (Synthesis) phase, where DNA replication occurs, ensuring that damaged DNA is not replicated. This provides an opportunity for DNA repair to take place before proceeding with the cell cycle.
Therefore, the correct answer is 1. G1. The p53 enzyme system prevents progression to the S phase by halting the cell cycle in G1 to allow DNA repair or apoptosis.