Cancer and Genetics
In the year 2013, the number of estimated deaths caused by cancer was of 580, 350. In which 306,920 were of men and 273, 430 were of women.
Cancer attacks the smallest structural unit of human life in the body, the cell. It corrupts the substance that genetically defines who we are, our DNA. When certain cells in our body are affected or mutated, if their reproduction is not controlled, they will cause all sorts of disorders. Factors like, tobacco, infectious organisms, chemicals, radiation, inherited mutations, hormones, immune conditions, and mutations that occur from metabolism are the ones that mainly impact our genes and are very capable of developing cancer.
Mutations can be inherited when organisms reproduce. In human reproduction for example, when the sperm of the father fertilizes the ovum of the mother, one of the gametes of either parent can be carrying the pair of genes containing the altered ones. When the zygote is formed and developed, it is likely to be totally contaminated with carcinogenic cells. Nevertheless, inherited mutations are less probable of developing cancer. They must combine with other factors, like bad habits (E.g. smoking) to form cancer. If the disease was not inherited, though, the victim will have acquired it during the progress of a lifetime.
How does cancer alter our genes? Each gene carries part of our DNA codification. There are different types of genes in the human genome that take care of the tasks within a cell. Those that control the cell growth are the ones that cancer uses to develop. When cell growth gets out of control tumors and mutations will result. When the mutations accumulate over time in the different genes of cells, they will ultimately become cancer cells. These altered cells are alive and reproduce rapidly. It is important to note that because cancer occurs within the genes of cells, it is not contagious.
The genes that take care of cell growth are known as proto-oncogenes. Specifically, these genes are the ones that identify the kind of cell and have the code that tells the cell how often to divide. Cell division plays one of the most important roles in the cell cycle because it is the one that passes the DNA of the cell to its daughter cells. Proto-oncogenes tell the cell how and when to start the division. When these genes become defected or abnormal, they might turn on the cell or activate it when it is not meant to be. This will ultimately cause irrepressible growth of cells that presumably leads to cancer. Proto-oncogenes are known to be dominant at the cellular level, because in order to form tumors, only one pair of the proto-oncogenes has to be mutated. A mutated proto-oncogene is called an oncogene and they are normally acquired, not inherited.
Other types of genes that lead to cancer are the tumor-suppressor genes. These genes normally control the activity of cell division by slowing it down; this, in turn, controls the cell growth. They also govern protein activation, the repairmen of DNA mistakes, and the cell’s death (known as apoptosis). Using these processes, these genes can also remove or suppress the development of tumors. When they are mutated, however, they can promote the creation or growth of tumors. Tumor-suppressor genes, when mutated, become inactivated and speed up cell growth and division. Mutations inn these genes are usually acquired. Both pairs of genes have to be mutated to cause tumors and cancer, thus, are known as recessive in the cellular level.
The difference between oncogenes and tumor-suppressor genes is that oncogenes are the result of the uncontrolled activation of proto-oncogenes and the other cause cancer when they are inactivated. Cancer is caused by many factors and it involves different alterations of genes. Therefore, it is not simple to find one single cure to heal all the diseases caused by it.