Q2CC - Campbell Biology

Question

How does MPF allow a cell to pass the G₂ phase checkpoint and enter mitosis?(See Figure 12.16)

Step-by-Step Solution

Answer

The cell passes the G₂ phase due to the presence of a sufficient amount of MPF. It happens by the combination of cyclin and cdks. The phosphorylation of other proteins follows it to start the mitosis process. 

 

Step 1: Description of Mitotic promoting factor

The maturation promoting factor is otherwise called as mitosis promoting factor. It is a protein complex that initiates the process of mitosis after a regulatory checkpoint. 

Step 2: Description of G 2 phase checkpoint

A cell cycle checkpoint is a scanning within the cellular mechanism to avoid the multiplication of damaged cells. G₂ phase checkpoint is the checkpoint in which the chromosomes and DNA are checked for damage before they enter into mitosis.

Step 3: Cell in G 2 phase checkpoint and entry in mitosis

The cell has to get into the G₂ checkpoint with the help of the mitosis-promoting factor (MPF). MPF gets activated only by combining cyclin with Cdks. 

Cyclin is the protein that regulates the cell in the cell cycle process. Cdks is the kinase protein dependent on the cyclin. Therefore, enough accumulation of cyclin indirectly triggers theG₂ phase checkpoint. 

After the activation of MPF, it, in turn, activates the other protein resulting in the activation of the mitosis phase, and the cells can enter this phase after the G₂ phase.