As I sat in class attentively listening to a lecture on the replication of DNA in the process of cell division I could not help but think about how this very process, occurring countless times, might be very destroying my body at that very moment. Most of the trillions of cells in our body need to divide to survive and grow their respective tissues and organs. With each cell division and/or nuclei division comes the need for DNA replication. The cell first begins to grow and mature, then at a point it decides it needs to divide, creating more cells. To do so the first step is DNA replication, taking place in the S phase of interphase, so that once the nucleus divides in half the resulting daughter cells contain equal and full amounts of genetic information.
The process of DNA replication consists of copying every gene into a second identical chromosome therefore creating double the genetic information in the cell. There are so many genes amongst the 23 chromosomes that need to be copied and our body is not 100% perfect so it is inevitable that our body will make a mistake in the copying process. These mistakes happen at a very low rate, but they can still be present. Once these occur the body has ways to get rid of the mistakes so they are not harmful to the body. They cell may be signaled to undergo apoptosis, instructed cell suicide, or the DNA can be repaired by an enzyme. These repair enzymes recognize structural imperfections between improperly genes in the DNA, cutting out the wrong ones and correcting them so that the right ones are in their place. But some replication errors make it past these mechanisms, thus becoming permanent mutations.
These permanent mutations build up in the body and are what lead to an estimated 6000 different diseases, including all varieties of cancers. Because of the rarity of these mistakes they most often seriously affect the body at older ages. Over time the body accumulates more and more of these abnormalities so there is a higher risk for disease, this is why there is a higher rate of cancer in older people than there is in those of younger ages. It is believed by researchers that if genetic mutations causing disease were eliminated as risk factors for death then humans would regularly live 100 years or more. One reasons humans have such a long life span, even with the mutations, is because each cell is programmed to divide 45-55 times before it is too old to continue this process. This division occurs so that our defective or dead cells may be replaced, in return extending our life span.
So with this understanding that I may potentially have multiple new mutations each day because of the large number of mitotic cycles I undergo given of my body’s current stage in growth, it is easy to comprehend the intrigue in the thought that a cell division happening right now in my body could be devastating. Although these mistakes are natural and little can be done about them it is still somewhat of an odd and unsettling thought that life threating errors could be and are happening to some of the cells in my body everyday, even as I study the very topic.