Mom is the Source of your Energy

Okay, so this week my students learned cell biology in summary. I mentioned that all your mitochondria comes from your mom!

Let’s go back a bit … you know it starts with the sperm and the egg. While the sperm has mitochondria, its mitochondria is located in the neck. During the fertilization process, the only thing coming into the egg from the sperm is the DNA from the head of the sperm – everything else, including the sperm’s mitochondria stays outside of the egg’s cytoplasm.

But within the egg, there already is mitochondria, and it’s from these mitochondria that give rise to all other mitochondria as this zygote divides into 2 to 4 to 8, etc.

So the sperm (and the guy) is responsible for the gender of the child, the egg (and the mom) is responsible for all the mitochondria. This is significant in genetics and tracing some mitochondrial diseases.

P.S. How is a guy responsible for the gender of the child, you ask? Males are males because they have sex chromosomes “XY” while females are females because they don’t have the “Y” – females’ sex chromosomes are “XX”. When the males sperm form by meiosis in the testes, some sperm have X and others have Y. The female’s eggs in the ovaries will each have an “X,” because that’s all she has. So when in fertilization the sperm meets with the egg, the egg provides the X and the sperm will either provide an X or a Y. If the sperm provides a Y, then the offspring will be XY – a male! If the sperm provides an X, then it’s a girl: XX!

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