If all the cell in our body are replaced at some point in our life, why do we get old and die?
In: Biology
When your body replaces cells, they make a copy of them to do so… So imagine taking a picture of a picture, do it hundreds of thousands of times and the quality drops to unsustainable levels.
Each strand of dna that contains the code to build the cell has what’s called telomeres. These are at the core a buffer for the dna. Each time your dna copies itself, a small bit is lost in transition, typically from the telomeres at the end. Once the dna strands lose too many of them, core dna becomes corrupted. This corruption prevents additional copies from being produced and results in a degrading effect, aging. And once the majority of critical body systems are unable to make copies, the entire system experiences a shutdown, death.
At least this is what I remember from highschool biotech from 10 years ago…
Cell replacement slows and eventually becomes rife with chromosomal errors, at least for many cells in the body. Telomeres are little bits that “cap” the end of chromosomes, and they protect the chromosome when it divides, reducing replication errors and mutations. These telomeres shorten with each replication, so that over time, more and more replication errors and mutations happen. Eventually, those errors interfere with further replication and cells can no longer replace themselves, and that’s that – tissues break down, you age more and more, and you die.
There are only so many times a living cell can divide. That’s dictated by a protein inside our cells called Telomeres which gets shorten every time cells divide. Once that Telomeres reaches terminal length (after 50-70 cell divisions), those cells simply stops dividing and dies.
The main theory is that every time your cells split the dna degrades slightly, so after long enough some cells stop working and just die.
The process of replacing our cells does not make a perfect copy.
Instead, every time our cells divide, things called telomeres get a little shorter each time. Eventually they get too short to work properly, leading to the effects of aging.
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