Our bodies renew themselves with no input from our (conscious) minds: for example, the lining of our intestines replaces itself about every five days. In contrast, the endothelial cells of the heart, located inside blood vessels, power on for six years at a stretch. Transformation at such incremental scales hinges on one molecule that literally undergirds our physical and social identities: this is, of course, DNA.
A DNA molecule can have one of four “bases,” abbreviated as C, G, T and A. Visuals usually depict DNA strands in a “double helix,” a three-dimensional spiral that maximizes efficiency in base-pairing; chemical base-pairing usually occurs between C and G, or A and T. The “central dogma” of biology once dictated that most DNA (sectioned in discrete pieces called genes) simply provided instructions for making proteins. However, scientists who completed the Human Genome Project in 2004 realized that a scant two percent of the DNA codes for proteins. Many commentators who applied the overarching paradigm to this disconcerting fact declared the other 98 percent of our DNA “junk,” a euphemism that obscured the truth: the purpose of this DNA was unknown.
Cell types differentiate not by inheriting separate sets of genes, but by controlling which genes become active. Much of the once-disparaged “junk” DNA in our genomic orchestras actually takes on the role of conductor, regulating gene activity (the duration of the concert) and gene expression (the volume of the particular symphony being played). After a DNA strand “unzips” during translation – the “note-reading” needed to that gene’s correspondent protein – it can briefly fold into other dynamic shapes. Marcel Dinger, Daniel Christ and colleagues at the Garvan Institute for Medical Research in Australia recently located one of these shapes inside human cells for the first time. Dubbed the “i-motif,” it creates a bump in the smooth loop of the double helix (the “i” refers to intercalation, or the temporary bonding between Cs, rather than the typical C and G).
I-motifs occur in “promoter regions,” upstream of protein-coding genes, and might help dictate whether a gene switches “on” under specific cellular conditions. Alternatively, it could be an artifact of the cellular environment that does little of note. However, research like this still allows us a window into the neglected complexity of how the most miniscule elements of life communicate and synergize to write the larger story of all that moves and breathes and has its being.
Each human body’s 37 million cells constantly replicate their DNA to uphold the integrity of their tissues, inevitably accumulating errors known as mutations. Despite this, “we are all not walking bags of cancer,” as Sarah Zhang recently wrote in The Atlantic (May 8, 2018). How can this be? To prevent such catastrophe, cells manufacture suites of specialized enzymes that correct trillions of errors every second. In a November 2017 sermon on this topic, John van Sloten – a pastor who frequently preaches about science – said, “This [repair] is happening right now, a physiological parable spoken by, in, through and for Jesus Christ.”
His body, broken for us, allows our bodies to be broken, rewoven and restored with every breath we take.
Watch John van Sloten’s sermon, “God’s healing power in your DNA,” at vimeo.com/241581880, part of a sermon series on “God’s Body Language.”
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