|
|
Electric DNACreation magazine has shown how DNA is the ultimate information storage molecule in the universe.1 We also showed how cutting-edge discoveries refute the idea of ‘junk’ DNA, which doesn’t code for proteins, showing that this has an amazing array of functions that we are only just beginning to learn about. Dr John Mattick, a leading researcher into DNA function, proposes that ‘junk’ DNA acts like an advanced computer operating system.1 More recently, he lamented how the idea that non-protein–coding DNA was just junk had greatly harmed science: Photo <www.stockxpert.com>
‘The failure to recognize the full implications of [non-protein–coding DNA] may well go down as one of the biggest mistakes in the history of molecular biology.’2 Electric protectionAnother intriguing property is how DNA in cells conducts electricity.1,3 DNA is easily damaged. Some chemicals, including free radicals, attack DNA by stealing an electron from (i.e. oxidizing) one of the bases—the chemical ‘letters’ of the DNA code. The resulting electron ‘hole’ can hop along the DNA, behaving like a positive electric current. We already reported that some of the ‘junk’ DNA comprises pairings between the ‘letters’ A and T (the bases adenine and thymine), and this blocks this damaging electrical current. These pairings act as insulators or ‘electronic hinges in a circuit’ to protect essential genes from electrical damage from free radicals attacking a distant part of the DNA.1 More recently, Jacqueline Barton of the California Institute of Technology has shown that DNA also uses its electrical properties for protection. At the edge of some genes, there is a string of G ‘letters’ (the base guanine). They readily absorb the electron hole, so the electron hole moves along until it reaches this string of Gs. This deflects the damage from the parts of the DNA that code for proteins.4 This is very much like the principle behind galvanized iron. Here, a coating of a more reactive and less important metal, zinc, sacrificially takes all the oxidation, thus protecting the iron from rusting. DNA errors are scanned electricallySuch ingenious repair machinery must have been present in all life right from the beginning. Our cells have elaborate machinery to repair DNA. But with 3 billion ‘letters’ worth of information in every cell, there is a lot to scan for errors. However, unbroken DNA conducts electricity, while an error blocks the current. Now Dr Barton has found that some repair enzymes exploit this. One pair of enzymes lock onto different parts of a DNA strand. One of them sends an electron down the strand. If the DNA is unbroken, the electron reaches the other enzyme, and causes it to detach. I.e. this process scans the region of DNA between them, and if it’s clean, there is no need for repairs. But if there is a break, the electron doesn’t reach the second enzyme. This enzyme then moves along the strand until it reaches the error, and fixes it. This mechanism of repair seems to be present in all living things, from bacteria to man.5 Such ingenious repair machinery must have been present in all life right from the beginning, otherwise life could not have survived breaks in its DNA. As scientists discover more of the intricate design of life, we can see more how we are ‘fearfully and wonderfully made’ (Psalm 139:14).
References and notes
|
||


