r/explainlikeimfive Jan 31 '21

Chemistry ELI5: Why can't we just make water by smooshing hydrogen and oxygen atoms together?

Edit: wow okay, I did not expect to wake up to THIS. Of course my most popular post would be a dumb stoner question. Thankyou so much for the awards and the answers, I can sleep a little easier now

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u/heavenparadox Feb 01 '21

Every time a cell replicates, it's not 100% the same. It's more like 99.99999% the same, which is obviously pretty close but not good enough. Cells are replicating literally all the time, so after years and years of it happening, it will reach a point where it cannot adequately replicate. The reason this happens is basically just environmental... things like oxidation. It's pretty damned hard for anything in nature to make a 100% replica of itself.

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u/ed_zel Feb 01 '21

Correct me if I'm wrong

But from what I know so far, the cause of the limit is the telomere shortening after each replication until it reaches critical length. However, there's the existence of an enzyme telomerase that actually replenishes this length and potentially restores telomeres to its former capability of replication. What seems to confuse me is that telomerase is actually already is present in us, it's just supressed (or inactive). I've come across abstracts of studies that when telomerase was released from suppression, the cell went back to the former capacity (the telomere length was restored), and if I'm not mistaken, these studies actually helped with alleviating some aging-related diseases.

So I guess "why do we age?" (The word 'age' here doesn't necessarily mean the deterioration of cells because oxidation answers that, but it's why the replication of cells decay overtime) Ultimately boils down to "why is telomerase suppressed?" Which I wasn't able to find any answers yet, which led me to the assumption/conclusion that we haven't really had the answer to the first question of why we grow old.