To be honest, I didn’t know a lot about mitochondria or aging diseases before I started my PhD!
The way you apply for PhDs is very different to any other courses before then – for GCSEs and A-levels you just choose from the list of classes that your school does, and for your degree you apply for one type of course at lots of different places. When you apply for a PhD its different because you apply for lots of different things within a certain topic area – this is because no 2 PhDs are the same, even in one lab, as a PhD is defined by being ‘unique and original research’. This is really good, because your pretty much the world expert in the topic that you end up studying, even though you probably don’t know a lot about the topic before you start your PhD! But it does mean that every title is very specific, and no two PhDs are alike, so you apply for a lot of very different titles.
In my case, I was interested in genetic diseases, so I applied for lots of PhDs based on linking genes to illnesses. Studying mitochondrial DNA in aging diseases is one of the courses I was accepted for, and I really liked the lab it was based in as well as the topic, so I chose this one 🙂