DNA: the blueprint for life
Chromosomes, genes, DNA, exons, telomeres…the terminology surrounding genetics can be mind-boggling. But a little understanding goes a long way toward appreciating the role genetics plays in the development of certain diseases in our dogs, including cancer.
Deoxyribonucleic acid is a complex molecule that contains the “blueprint” for all the biological processes that occur within a cell. DNA is passed from parent to offspring, as well as from cell to cell during cell division. DNA is composed of four different molecules, paired with each other and then “twisted” into the double helix shape seen in pictures and diagrams.
Chromosomes are large collections of DNA. Chromosomes come in pairs, with individuals inheriting one chromosome from each parent. Chromosomes are composed of a single (but very long) molecule of DNA, and proteins called histones. The DNA is wound tightly around the histones (think of a spool of thread) because it is an efficient way to package the long strands of DNA. If the DNA contained in a single human cell was placed end to end, it would stretch 6 feet!
When the DNA blueprint is needed for cell functions, the DNA unrolls off the histone spool and provides direction to the cell. Once this is completed, the DNA rolls back onto the histone.
Genes are regions of DNA that code for a particular trait, like hair color or height. Using our thread and spool example, imagine that the thread is multicolored. Red blends into green which blends into blue, each section varying in length. Now think of each color as a gene, each region coding for a specific protein. Many researchers, both in veterinary and human medicine, are interested in learning which genes are responsible for different traits, and where those genes are located within a chromosome.
Once a gene is located and its function determined, researchers can begin to correlate gene differences to traits in individuals. They also can look to see if mutations in, or specific forms of, a gene are associated with disease. An example is the recent discovery by Morris Animal Foundation researchers of genes in golden retrievers associated with the development of certain types of cancers. Finding a link between a gene and a disease is a necessary step toward developing genetic tests to identify at-risk individuals.
We’ve still got a long way to go before we have a complete understanding of the genetic make- up of domestic animals, but Morris Animal Foundation is funding studies to advance our understanding of the dog genome and that of other species. Once we “crack” more of the code, we will have valuable tools to study not only inherited disease, but also expand our understanding of how genetics influence the development of diseases in dogs and other animals.
(Image courtesy of the University of Waikato.)