DNA Damage and Apoptosis: Understanding Cell Division Checkpoints

During which checkpoint did a cell with twice the amount of DNA trigger apoptosis?

A. G1 checkpoint
B. G2 checkpoint
C. M checkpoint
D. No checkpoint meets these criteria

Answer: G2

What is DNA?

DNA, commonly referred to as deoxyribonucleic acid, is the genetic material carried by humans and nearly all other organisms. Nearly all of an individual's cells have their DNA. Nuclear DNA, which makes up the majority of DNA, is located in the cell nucleus, with very little DNA being present in the mitochondria (where it is called mitochondrial DNA or mtDNA).

The coding that stores information in DNA is made up of the four chemical bases adenine (A), guanine (G), cytosine (C), and thymine (T).

The cell contains an additional checkpoint called the G2 checkpoint before the M phase to ensure that cell division proceeds smoothly and produces healthy daughter cells with intact, undamaged DNA. At the G2 checkpoint, the cell will check for DNA consistency and DNA synthesis. If errors or damage are found, the cell will stop to allow for repairs.

If the checkpoint mechanisms identify DNA abnormalities that cannot be repaired, the cell may go through apoptosis, or programmed cell death, to prevent the passing of damaged DNA to daughter cells. This self-destruction mechanism is crucial in avoiding cancer.