Molecular Machines

[SeattleGriz]

This is the sort of stuff that has me scratching my head. Why, and how could this sort of machine evolve?

[youtube]https://www.youtube.com/watch?v=gbycQf1TbM0[/youtube]

So the main question is:

Could nanomachines produced for specific purposes arise by chance when they depend upon detailed information both for their making and their function (taken from a website).

To rephrase, how could something that is built for a specific purpose, first build up the genetic information (blue print) in the first place? How does this happen with mutation and natural selection? You need to increase the genetic information to create the machine? huh.

Both mutation and natural selection are unguided. How do they know?

[SeattleGriz]

JMU DJ, we need your mind!

[JMU DJ]

So I believe this goes into gene duplication. I'm not an evolutionary biologist, so I'm not that deep into it. IN THE BEGINNING, there wouldn't have been molecular motors like kinesin and dynein, two of the major molecular motors involved in cell division. So, if you think about it, when a cell divides there is duplication of genetic information and that is split in half upon division. That doesn't always happen and you can end up with genetic duplication, or a cell ends up with double the amount of genetic information than is required. This can happen rapidly, there was a study in Yeast (which contains these molecular motors) that saw genetic duplication of a gene in under 500 generations (yeast doubles about every 1.5 hours, so 500 generations isn't that long of a time, about a month.). Without specialized molecular motors, you can imagine this might happen a lot more frequently. The way that cells deal with genetic duplication is through mutagenesis and deletions. You can see this in the Myosin gene family where multiple instances indicate domain deletion.

In short, genetic duplication though division, expansion of genome, mutagenesis/deletion of segments of duplication, alteration of function, passage of genetic information to the next generation.

[Chizzang]

This is the sort of stuff that has me scratching my head. Why, and how could this sort of machine evolve?

[youtube]https://www.youtube.com/watch?v=gbycQf1TbM0[/youtube]

So the main question is:

Could nanomachines produced for specific purposes arise by chance when they depend upon detailed information both for their making and their function (taken from a website).

To rephrase, how could something that is built for a specific purpose, first build up the genetic information (blue print) in the first place? How does this happen with mutation and natural selection? You need to increase the genetic information to create the machine? huh.

Both mutation and natural selection are unguided. How do they know?

The question "why and How" could something like this evolve - only matters - in this context if you're searching to make the same old argument... Sadly foiled by yeast I see

Anyway: I'm still waiting for somebody to walk on water (anybody really) you'd think evolution would have stumbled on that one by now

[CID1990]

Sadly foiled by yeast

I said that once after a cofc sorority party

Anyway: I'm still waiting for somebody to walk on water (anybody really) you'd think evolution would have stumbled on that one by now

I walked on water once- was swimming in a pond on my farm when I was a kid and saw a water moccasin swimming towards me

[JMU DJ]

Anyway: I'm still waiting for somebody to walk on water (anybody really) you'd think evolution would have stumbled on that one by now

[youtube]https://www.youtube.com/watch?v=Qhsxo7vY8ac[/youtube]

Sadly foiled by yeast

I said that once after a cofc sorority party

[Chizzang]

Sadly foiled by yeast

I said that once after a cofc sorority party

Anyway: I'm still waiting for somebody to walk on water (anybody really) you'd think evolution would have stumbled on that one by now

I walked on water once- was swimming in a pond on my farm when I was a kid and saw a water moccasin swimming towards me

PURE GOLD!

[SeattleGriz]

Thanks JMU. So for my next question, any idea of how the microtubules know where to assemble so the kinesin makes its destination.

Just your thoughts when you get a chance.

[JMU DJ]

Alright, so microtubules form near the center of the cell and they elongate by moving out from the center. The end that is elongating and shrinking is the + end, whereas the - end is anchored near center. Kinesins always move from - to +, Dynein always moves from + to - (see cartoon)



Below, you can see these are everywhere in the living cell (green is tubulin). If you can imagine, it wouldn't be too hard for a protein like kinesin to find a microtubule to walk on. There are multiple different forms of kinesins and they're projected to bind different types of vesicles and organelles.



I think that field is still in progress, i.e. what kinesins move what vesicles, how those interactions form (kinesin-kinectin), etc. Take this semi recent article for instance that discusses how kinesin may bind microtubules.

Here we use atomistic Brownian dynamics simulations combined with experimental mutagenesis to show that incoming kinesin heads undergo electrostatically guided diffusion-to-capture by microtubules, and that this produces directionally biased binding. Kinesin-1 heads are initially rotated by the electrostatic field so that their tubulin-binding sites face inwards, and then steered towards a plus-endwards binding site.

or as stated in their more easy to process summary

We know that some kinesins have twin “heads” that alternately bind to and step along microtubules in a coordinated walking action. But more usually, kinesins have only one head. How single-headed kinesins produce force and movement is poorly understood. In this study, we address this question and show that electrical attraction between single kinesin heads and microtubules is a critical factor deciding the direction of movement: each time the head approaches a microtubule, it slides forwards by the electrical attraction between the engine and the track.

http://www.plosbiology.org/article/info ... io.1001207" onclick="window.open(this.href);return false;