Each of the 10 trillion cells of your body receives tens of thousands of DNA lesions per day; that's tens of thousands of incidents of damage to your genome. The damage might be caused by mismatches during DNA replication, chemical interference, radiation, or ultraviolet light. Such damage, if not detected and repaired, can lead to mutations or other genomic aberrations that threaten cell viability, or even the health and well-being of the organism -- you.
Tens of thousands of incidents of DNA damage in every cell every day! Our genomic integrity is under constant attack -- the integrity that makes you you and me me, and keeps our bodies on track to a normal healthy life.
To combat these threats, cells have evolved mechanisms -- collectively called the DNA-damage response (DDR) -- to detect damage and facilitate repair.
Imagine, if you will, little quality-control inspectors patrolling up and down the DNA strands, checking for mismatches or breaks, then calling on their cell phones for repair crews to speed up in their vans and put things back in order. It is proteins -- yes, proteins, strings of amino acids folded into elaborate shapes -- that do the job of inspecting, signaling and repair!
In the 22 October issue of Nature, biochemists Stephen Jackson and Jeri Bartek take eight pages to sketch what we know about the DDR. They conclude:
Great progress has been made towards understanding the DDR but much remains to be learned. One major future challenge is to understand in more detail how the activities of DDR proteins are controlled. Other challenges are to determine precisely how and why the DDR impacts on myriad cellular functions and how such complex programmes are orchestrated. Additional important issues to be addressed are how the DDR can be shaped and fine-tuned by other pathways and events, and how the same DDR stimulus can yield markedly different responses in different cells and tissues, including cancer cells and stem cells. Such knowledge will not only enhance our appreciation of DDR functions but will undoubtedly present exciting opportunities for better understanding and managing human health and disease.So what does all this incredibly sophisticated biochemistry have to do with you and me, aside, that is, from the fact that it keeps you you and me me? It happens without the slightest necessity of consciousness on our part. It was evolving for 4 billion years before any conscious organism even knew it existed. Why think about it now?
Because knowing is better than not knowing. Because knowing is what makes us human. Because even a superficial awareness of what is happening in every one of the 10 trillion cells of our bodies is a source of wonder, and ground for a -- yes -- religious response to the world -- a response that affirms a Mystery made more manifest by every advance in knowledge, and doesn't cheapen that Mystery by invoking the shabby agency of an anthropomorphic God.