light gazing, ışığa bakmak

Tuesday, November 3, 2015

'quality control' (stuff one reads)

By a wide margin, the most amazing achievement in quality control takes place during a biological process which is millions of years old—the growth of the fertilized egg into an animal organism. In human beings the genetic instructions which program this growth consist of a sequence of about three billion “letters.” This sequence—the human genome—is contained in two strands of DNA (the double helix) which “unzip” and replicate about a million billion times during the growth process from fertilized egg to birth of the human being.
Given such huge numbers, the opportunities for error are enormous. (Some errors are harmless, but others are damaging and even lethal.) Yet the actual error rate is of the order of about one in 10 billion. This incredibly low error rate is achieved through a feedback loop involving three processes
(Radman and Wagner 1988):

- A high-fidelity selection process for attaching the right “letters,” using chemical lock-and-key
- A proofreading process for reading the most recent letter, and removing it if incorrect
- A corrective action process to rectify the errors which are detected

chame-se o que se chamar, é a vida.

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