(or 2!) Dying of old age, can you actually DIE because of the body being worn out, or is it always a disease or such? I read that if we cure every disease, we would live hundreds of years.

Question

Title! I don’t get it. Isn’t my finger getting worn from just being used for too long? Or will it eventually get worse because of something else?

In: Biology

Answer 1

As your cells replicate, they accumulate errors in the genes. 99% of the errors don’t affect the cell – think, like, the genes to make insulin get corrupted, but in muscle cells. It doesn’t do anything. But, eventually, inevitably, the damaged genes code for something important, relevant to that cell’s job in your body. Or, the messed up genes lead to cancer. As all this damage accumulates, your organs can’t repair themselves effectively or function properly.

Additionally, because of the way DNA is shaped and the way that enzymes copy it, the very ends of the DNA cannot be copied. Think of a zipper, which needs a little tab to grab onto before it can start zipping. The enzymes are like that, and the “tab” that doesn’t get “zipped” can’t be copied, so it gets lost. Luckily, our DNA comes with pieces, called *telomeres*, which don’t code for anything and are there solely to be lost when the DNA gets replicated. Unfortunately, we have a limited number of those. Cells that replicate very often may run out of telomeres, and then important genes on the ends do get lost.

One example may be the code for collagen, which helps make skin stretchy. Skin cells have to replicate a lot, so they run out of telomeres quickly. Collagen is one of the first genes that gets lost, which is why your skin stops being as stretchy and gets wrinkly as you age.

*Officially*, really, the cause of death is some kind of organ failure, probably connected to cancer.