It's a Hard Luck Life

... if you're a bacterium.

(notes for an eventual review of A Crack in Creation by Jennifer A. Doudna and Samuel H. Sternberg)

The life of a bacterium tends to be nasty, brutish, and short.  About half the bacteria in the ocean are killed every day by even smaller predators, bacteriophages.  Phages are virus that prey on bacteria by invading them, hijacking their cellular machinery to make more copies of themselves, and then exploding the victim bacteria to spread thousands of copies of themselves.

On the other hand, some bacteria  have lived a very long time.  Because they multiply by dividing, it's reasonable to say that every bacteria alive today has been alive since the very first.  Of course the same is true of all the cells of our body, all of which are descended in unbroken living descent from those first bacteria.

So how have bacteria alive today survived this ferocious predation by phages, not to mention all the other hazards of existence?  The answer is that they have very sophisticated and powerful immune systems.  These immune systems consist of an elaborate suite of  molecular machines that block, attack and destroy invading phages.

These bacterial immune systems are interesting not only because they allow the production of cheese, beer and yoghurt (by defending the responsible bacteria) but more importantly because the molecular machinery invented by bacterial evolution can be used to edit genes.

CRISPR, the latest and most sophisticated of these bacterial machines - more like a whole bacterial machine shop - and it is the subject of the book by Doudna and Sternberg.  I'm only on page 75, but it looks great so far.


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