Thursday, September 29, 2011

DNA Transcription and RNA Translation

This is an example of one of those moments in my science education where things... just... clicked.  Maybe you know the feeling.

I knew about DNA, RNA, transcription, translation, proteins, the nucleus, molecules, et cetera, et cetera, but this video, after watching it in my high school biology class made everything fit together in a coherent picture.

For me, the realization had a few parts.  First was:  proteins are molecular machines, and everything they can do is based primarily on their shape.  Everything in the video, aside from the double-helix DNA "red" strand, and the single-helix RNA "yellow" strand, is a protein or amino acid, those little red bits that get stuck together to make the deep red hemoglobin protein at the end.  (Since hemoglobin, which uses iron to carry oxygen through the blood, is responsible for the red color of blood, its color in the video might be accurate!)

But those big, chunky blobs throughout the videos are very special proteins that can only do what they do based on their shape.

Now, right at the beginning of the video we saw a bunch of these proteins latch on to the DNA strand, and several had to come together before the work could be done.  On a tangent, this is a perfect example of the "Intelligent Design" irreducible complexity argument.  The argument goes, "Well, see this thing here.  It couldn't work at all if you take one piece away, and if evolution always adds just one piece at a time to a structure, this would be useless until you had everything put together at the end, so evolution wouldn't select for any individual component.  Therefore, an Intelligent Designer/God/magic/a wizard did it!"  In this case, the process can be done by one protein acting alone.  Other proteins can be added to refine the process or speed it up.

My second realization took a bit of extra thought.  I was still confused as to how all these bits and blobs actually came together.  How do they find each other?  The truth is, the video doesn't show everything going on.  It can't.  What you aren't seeing is that big empty space inside the cell and inside the nucleus, is FULL of these proteins, amino acids, nucleic acids, strands of DNA and RNA, sugars, fats, everything!  The video shows a big open space with a few shapes inside working together, but that empty space is a soup of molecules partaking in similar interactions.  The video had to take that out just so you could see what they wanted to show you.

So the second realization was that molecules in your cells don't know what to do, and don't seek each other out, they're just all crammed in there together, they bump up against each other, and they react, based purely on chemical bonds and shape.  And it all just happens on its own purely because it can, and when it does it well it can keep doing it for years and years to come.

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