Cancer and the Blueprint for Life
DNA provides the life spark for all living creatures, be they plants, molds, or humans. Called “the blueprint for life,” DNA is awesome in power and graceful in design, a natural creation of breathtaking beauty and sweeping simplicity. Imbued with immense responsibilities, DNA is the keeper of our heredity and enables us to pass on family traits from one generation to the next. DNA holds the keys to understanding evolution, human development, and most human diseases.
Consider the role of DNA in human development. From the moment the egg and sperm fuse to form one cell called a fertilized egg, the DNA within that cell starts to work its magic and executes an ancient plan. The DNA spearheads an explosive phase of growth that turns one cell into the trillions of cells that compose our bodies. At the same time, DNA guides some cells to form our lungs, others to form our fingers, and still others to form all our various parts. Imagine how one cell, too small to see without a microscope, can give rise to a brain with all its complex thoughts; a ticking heart, pumping blood throughout the body; eyes that see the world; a stomach that grinds food; and all the other tasks of which we are capable. And after we burst forth into the world, we passage through infancy, childhood, adulthood, and finally old age. All these changes, which may seem magical to us, are precisely choreographed by our DNA; they are also heavily influenced by the outside world (feed a developing fetus alcohol and normal development is drastically altered).
The magic, therefore, is in the workings of DNA. But what is DNA and how does it accomplish such amazing things? DNA is a stringy substance that resides in the inner chamber of each cell in a location called the nucleus. From this vantage point DNA sends forth its orders that direct the cell how to interact with other cells, when to multiply, and when to die. Whereas animals use their eyes and ears to communicate, DNA uses proteins to convey its messages. In order to make these proteins, DNA first generates a related compound called RNA. The flow of information from DNA to RNA and then to protein is called the “genetic code” .
If we were to look closely at DNA, we would see that it is composed of repeating units of four similar chemicals, called bases (or nucleotides):
A for adenine, T for thymine, G for guanine, and C for cytosine. Each human cell’s DNA, or genome, is composed of three billion bases, one connected to the next like pearls on a string.
This string is not continuous, however, but is broken up into twenty-three separate units called chromosomes. When the bases are arranged in a particular order in the DNA, a gene is formed and a cell has the instructions it needs to make the corresponding protein. Although DNA contains the blueprint for the functioning of our bodies, the proteins do the actual work. Proteins are made up of chemicals called amino acids. For example, insulin is a protein that regulates blood sugar; it is made in the cells of the pancreas following the directions of the insulin gene.
Similarly, red blood cells contain the oxygen-carrying molecule hemoglobin, which is made from instructions contained in the glob in genes. Every gene consists of A’s, T’s, G’s, and C’s, but the specific ordering of these bases makes each gene unique.
There are genes for every aspect of human functioning-from genes that control brain activity to those that make our nails grow. As they relate to cancer, there are genes that make a cell multiply and those that generate a blood supply for a growing tumor; there are even genes that can naturally antagonize these processes (hallelujah!). In total, there are about twenty-five thousand human genes as determined by the monumental accomplishment of the Human Genome Project, which deciphered all three billion bases of human DNA.
