Inheritance of DNA

There are actually two types of DNA and I’ll explain these. The first is the Nuclear DNA but there’s also another kind of DNA known as Mitochondrial DNA. The nuclear DNA, as the name suggests, is found within the nucleus of the cell and this is the one that we are typically referring to. The mitochondrial DNA is found in special structures in the cell, out in the, the cytoplasm of the cell, or the egg white, and these structures are called Mitochondria. They are used to generate energy within the cell that the cells need to be able to grow and survive. When we refer to mitochondrial DNA, it will always be referred to as either mitochondrial DNA or mtDNA.

So, when there is no reference to anything, if it is just listed as being DNA, it is always implied that we’re referring to nuclear DNA. So we know of DNA, Deoxyribonucleic Acid, as your genetic blueprint. It is the code that is used to create you and it determines whether you are biologically male or female. It plays a very important role in what you look like and things like how tall you are, or hair color, eye color, these are all coded by your DNA. It’s also very important to your health and your DNA could actually predispose you to certain diseases throughout your life. Importantly you inherit your DNA equally from your biological parents.

So, every one of us, the nuclear DNA that we have, has come from half of each of our biological parents. So here’s the summary of how DNA is inherited. As I said, we have our nuclear DNA and for both males and females, we can see the rule is that DNA is inherited half from each of those biological parents. For mitochondrial DNA, however, both males and females will inherit their mitochondrial DNA from their biological mother.

There are very rare reports where people occasionally have found to have mitochondrial DNA from their father as well but those reports are rare and the typical pattern of inheritance is that we inherit our mitochondrial DNA from our mother and that occurs no matter whether we are male or female. Now, in regards to the Y chromosomes I mentioned before, males have a Y chromosome. Now this is part of the nuclear DNA, but it is a slightly special case. Men can only inherit their Y chromosome from their biological father because of their two parents only the father has a Y chromosome that he can donate.

They can’t inherit a Y chromosome from their mother, of course, because their mother doesn’t have a Y chromosome. So you can see here that in men who are X Y, they must inherit that Y chromosome from their father. That is the only possibility. And for females who are X X, two X chromosomes, they of course don’t have a Y chromosome, so that bit is not applicable. In regards to the X Chromosome, so men who are XY, they will inherit their Y chromosome from their father, they therefore must inherit their X chromosome from their biological mother. Whereas females, who are XX are actually inheriting one X chromosome from each of their biological parents.