What is the wobble hypothesis, and how does it explain the degeneracy of the genetic code?


microphone off – definition of “wobble hypothesis” found below.

What happens in DNA replication (cell division requires an entire new copy of the six-billion-plus codons that make up human DNA) is that fantastic error detection and correction mechanisms are hard at work. Yes mistakes happen, from missing genes to extra copies of genes to missing chromosomes and extra copies of chromosomes.

But the normal upshot is that about fifty of the six billion codons come out wrong. In data terms, the six billion codons are the rough equivalent of 2,000 beach-read novels, each with something more than 150,000 words. Out of those, one novel in 40 has one typo inserted. The literary quality, the grammar, the passion – basically unchanged.

The other side of that coin is that evolution is red, raw, impatient, and unstoppable. Consider that cell divisions needed to make the 100,000,000 cells in your body have to stack almost 50 deep; that means the final 50,000,000 cells’ DNA contains 2,500 – ish typos, or just over one per novel. And, not to be too dramatic about it, no two cells in your body are ever likely to have *identical* DNA.

Copy errors in your germ cells do *NOT* affect you. They *DO* affect your offspring.

This constant micro-vibration in DNA, across a population, can produce novel results. But we get along very well, thank you, with slightly differentied DNA from one cell to the next. Our children do the same. As long as the environment stays pretty much the same, the optimal DNA will stay the same too. But when there is some major change in the environment, the micro-jitter in the overall population’s DNA enables the species to drift, across many hundreds of generations, toward whatever the new optimum is.

Note well, the following definition of wobble says it is *possible* but does not quantify it – no definition of how often it happens. Fifty such errors typically get through the filter.

DEFINITION courtesy of Uncle Google: Wobble hypothesis: normal base pairing can occur between nitrogen bases in positions 1 and 2 of the codon and the corresponding bases (3 and 2) in the anticodon. Actually, the base 1 in anticodon can form non-Watson-Crick base pairing with the third position of the codon.

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