After a bachelors, a masters, and a PhD, I can confidently say I don't fucking know how anything works in biochemistry. Every protein in every pathway affects every other protein in every other pathway in every possible way and is involved in every possible disease in both positive and negative manners. Biochemistry is a complete and utter clusterfuck, it's literally incomprehensible. The more you learn, the less you know, but it still consumes all of your memory so you have no room for anything else. I don't know anything any more.