If you were asked, are you more like your mother or your father, what would you say? This is a difficult question to answer. Fortunately, the work of an Austrian monk in the mid 1800s named Gregor Mendel established our basic understanding of the laws of inheritance. Based on his work with pea plants, Mendel identified that specific traits, in the form of genes, are passed on from one generation to the next. Furthermore, he discovered that each parent passes a piece of that gene, called an allele, to their offspring. These alleles heavily impact what the offspring will be like. However, while Mendel’s discoveries have laid the foundation for our understanding of genetics, his work is only one piece of the genetic puzzle.
First, look at your hands. Now look at the hair on your arms. Lick your lips. While all of these parts of your body may look and feel different, they all have something in common: they are made of cells. Each of these cells has the same basic structure and components. One of the most important structures is something called DNA. Scientists have learned that there are multiple types of DNA in humans. One type is called mitochondrial DNA, which exists in tiny structures called mitochondria inside each of your cells. Mitochondria are like little engines that are responsible for turning the food you eat into energy. Without mitochondria, your cells and your body wouldn’t be able to do anything. Imagine a car without a motor; it’s not going anywhere!
The DNA in the cells in your body are a mixture from both your mother and father. Some specific sections of your DNA are called genes, which are responsible for specific characteristics, like hair color. When the sperm from your father mixed with the egg from your mother, the DNA from each was mixed together to create you. Now, let’s think about hair color for a minute. Your mother has DNA that codes for the gene to give her a certain color hair. Your father also has DNA that codes for a gene that gives him a certain color hair. Since these are both genes for hair color, they are essentially fighting for the same spot in your DNA. Usually, only one of these genes can win.
Scientists believe a similar competition happens with your mitochondrial DNA. However, in a recent study scientists discovered this competition is much more violent and intense. The scientists studied how mitochondrial DNA was passed on by doing an experiment with roundworms called C. elegans.
In their experiment, the scientists showed that mitochondrial DNA from the sperm of the father would self-destruct when it fused with an egg from the mother. Why would the father’s DNA self-destruct and not the mother’s? Is the father sacrificing himself for his children? What would happen if the mitochondrial DNA from both parents were passed on to the offspring? There are still many questions to be answered and even more to learn.
Just as in the roundworm, none of the mitochondrial DNA from our fathers manages to score a spot in our genetic lineup. Therefore, all of our mitochondrial DNA comes from our mothers. Our mother’s mitochondrial DNA came from her mother. We can follow this process back for thousands of generations, which implies that at one point there was a woman from whom all living humans inherited their mitochondrial DNA. Essentially we all have the same great-great-great-great (many greats) grandmother. So the next time one of your relatives says that you are so much more like your father, you can tell them they’re wrong. Whether you like it or not, you are more like your mother.
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