Osblog 49 – Genomics

Osblog 49 – Genomics

25th Apr 2017

When Watson and Crick discovered the DNA molecule they constructed a model to demonstrate the spiral. What looked like a twisting ladder made out of oversized matchsticks became the image we remember of DNA.  The Genome is incredibly simple in that it is just four different amino acids repeated in a varied sequence. The scientists deduced that the entire code for life was contained in the exact way compounds were arranged. Like the combination to a safe, the sequence was able to instruct proteins to construct other proteins to make a living thing.

What the matchstick model did not show was the sheer size of the DNA molecule. If we made the molecule with the matchsticks the size of pinheads the spiral would stretch 5,000 miles, probably from the Curragh to Arlington Park. This vast quantity of code contains sequences which switch on the protein production, other sequences switch the production off and specific patterns of code can be associated with specific proteins. In 5,000 miles of code there are vast deserts of information which do not seem to mean anything. They are assumed to be traces of long-since redundant instructions for life-forms lost along the evolutionary highway.

Other areas of agricultural production are far more advanced than the thoroughbred. The tomato genome is actually much bigger than the human or thoroughbred one. And far more is known about its component parts. The life cycle of the horse is relatively slow and the population is relatively tiny. More significantly, we measure very little about the thoroughbred. We know their race record. We might know their birth weight, adult weight, height, certain running capabilities. We don’t tend to share this information and so each breeder has an even smaller sample pool from which to develop the knowledge and to capture the sequence patterns in the genome.

There is a fear among horse people that this Frankensteinian science will make us all redundant. There are efforts at Breeders Association level to slow it down until we all get our heads around it. Any time there is a “knowledge gradient” there is a challenge and there is uncertainty. The fear that the future can be predicted by a simple test would close down the racetracks since the outcome would be considered foregone. This is not true. In fact the very scientists who have pushed out the boundaries so impressively over the last fifty years now admit that the genome is just like a 2D map with no topographical detail, no gradient, no weather reports. And in black and white. There are other factors at work – the environment obviously but also the epigenetics. This is the area where the details of the map are converted into activity within the cell. An infinite number of combinations and factors is at play.

The scientists also identify the other key ingredient in the genetic lottery – chance. Exactly how the sequence of genetic material is expressed will be subject to random acts of the universe making the result impossible to predict except in terms of a percentage of likelihood.  Racing remains the true test.

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