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Reduce This… part 2

May 24, 2010

Bacteria are a remarkable life form. Truly. They are quite possibly the most resilient forms of life on this or other planets. I say other planets because of this article:

http://www.msnbc.msn.com/id/34207864/ns/technology_and_science-space/

Fascinating stuff, really. It implies a lot of just mind blowing things but I won’t get into that right now. Right now we’re going to talk about one of the most ingenious little devices which bacteria have created for themselves: the bacteria flagellum.

First, let’s start with what the bacteria flagellum is. Below is a diagram I grabbed right off of Wikipedia. Sorry, I didn’t have the time nor the energy to make my own up this time.

 

Take a good look at it. Now, if you’ve taken a shop class at some point, it should immediately look familiar. It is, and there is no other way to say this, a motor. Really, check it out. It’s got a shaft, a rotator, etc. It’s a motor. Indeed, the flagellum is used almost exclusively in just that manor – for locomotion in the bacteria’s environment.  It really is a machine and I challenge any of you to find a better way to describe it.

Now, according to Irreducible Complexity, we should not be able to do two things:

1)      Remove any part or parts of this flagellum and get anything functional

2)      Find functions for the individual components when not in use as a flagellum

As for point one, the flagellum is broken into about 40 or 50 different genes. I won’t bore you with those details. Each gene maps to a protein which makes up one component of the flagellum. So, if we were to deactivate or just plain remove a chunk of them we should have something completely unusable, correct? Lets say, 30 or 40 of the genes which make up basically the tail of the flagellum were removed. Don’t ask how or why, the point right now is to remove them and show that the result is unusable. Here’s something we might get:

 

Yeah, that doesn’t look like mu…. WWWAAAAIT a minute. That’s a type-3 secretory system. Heh, yeah, I know, not really obvious, but that’s really what it is. Even the proteins are the same. The type-3 secretory system is another ingenious little device bacteria use in a similar manor that you might use a syringe – it injects proteins and other things into cells for multiple reasons. Reproduction, defense or to create an environment suitable for the bacteria by inducing certain auto-immune responses. Kinda cool, huh? Well, maybe not. That last one is how the bubonic plague works.

OK, so I found a use for it. So what? How did we get all the other parts?

Well, the proteins I removed are found everywhere in the bacteria’s DNA. It’s not hard to imagine how they can get swapped from one part to another. It’s a type of mutation called gene duplication. Happens all the time, including in humans. On top of that, intermediate forms of the bacteria flagellum are found throughout the animal kingdom but they each have different uses. The trick, it seems, is to not assume that an intermediate form has the same function as the current one.

So, here’s what we started with:

1)      We assumed the bacteria flagellum was irreducibly complex.

2)      The definition of irreducible complexity is such that

         2.a) None of the sub-components are useful on their own

  1.               2.ab) If you remove any part or group of parts from the mechanism, it would break

3)      But, removing a few genes from the bacteria will produce a type-3 secretory system instead of a flagellum – something used in several bacteria species

4)      Also, the proteins and genes we removed are duplicated elsewhere in the genome of most bacteria species.

5)      We’ve disproven 2.a and 2.b so our initial assumption must be incorrect.

Proof by contradiction.

And there you have it. Part 2 of “Reduce This”. Irreducible complexity… bullocks.

Most of the information I got was from this presentation by a great biologist named Dr. Ken Miller. He was actually part of the defense in the Dover’s trial and argued against the Intelligent Design proponents.

Anyway, next I’m not sure what I’ll be tackling. For the few of you who read this, send some stuff along. I’ll see what I can do.

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