Question

While reviewing a pathophysiology chapter on cell proliferation and tissue repair, the study group notices that the transition from G2 to M in the cell cycle is an important checkpoint and requires which proteins to be available to complete the process? Select all that apply.

Answer 1

The transition from G2 to M in the cell cycle is an important checkpoint known as the G2 checkpoint. This checkpoint ensures that all of the chromosomes have been replicated and that the replicated DNA is not damaged. The proteins required to complete the G2 to M transition include p53, p21, and CHK2.

Step-by-step explanation:

The transition from G2 to M in the cell cycle is an important checkpoint known as the G2 checkpoint. This checkpoint ensures that all of the chromosomes have been replicated and that the replicated DNA is not damaged. If there are problems with the DNA, the cell cycle is halted, and the cell attempts to either complete DNA replication or repair the damaged DNA.

During the G2 checkpoint, the cell also prepares to make the proteins necessary for the upcoming mitotic phase. These include nuclear proteins necessary to condense chromatin into chromosomes, tubulins for making microtubules, and more.

The proteins required to complete the G2 to M transition include:

• p53: a multi-functional protein that halts the cell cycle and triggers DNA repair or apoptosis depending on the severity of DNA damage.
• p21: a protein that enforces the halt in the cycle dictated by p53 by inhibiting the activity of the Cdk/cyclin complexes.
• CHK2: a protein involved in DNA damage response and cell cycle arrest.