Protein Synthesis: mRNA Processing

The enzymesProteins that speed up chemical reactions in the body. in your cellsThe basic structural and functional units of life. are always looking the catabolize or breakdown nucleic acids.  These enzymes are like Pac Men for DNA and RNA.  Strange, right?  No.  That’s why DNA is trapped in your nucleusThe control center of the cell that contains DNA and directs cellular activities..  Also, you are basically just a recycling center.  You eat the DNA of other organisms and break down their DNA and use the components to build back up your own.  Your cells are always digesting DNA. 

In order to protect the mRNA we put a helmet and steel toed boots on it before we send it out into the cytoplasmThe gel-like substance within a cell that contains organelles and cytosol..  This is a process called mRNA processing and it does more than just the helmet and boots.  The helmet and boots are technically called a cap and tail (although I still think helmet and boots is better…and funnier). This cap and tail are made of just a bunch of repetitive nucleotidesThe building blocks of nucleic acids., like a long chain of adenines added at the end.  This way, if any of those enzymes actually starts to eat into the DNA, no valuable parts of that coding sequence will be lost.  We can sacrifice the cap and tail and still make our protein.

The other things that happens in mRNA processing is something called splicing.  So, I kinda lied when I said one gene holds the recipe for one proteinsLarge molecules made of amino acids with various functions in the body..  That’s not true because splicing can give us a bunch of mini-sequences.  mRNA has lengths of sequences called introns and exons.  In a process called splicing, introns are removed from the transcript and exons are left over, glued together, and now form a mini-sequence derived from the originally transcribed sequence. 

This. Is. Genius.  This is how so many variations of protein recipes can be held by one gene.  With differential splicing, the possibilities of sequences are endless.  Well, maybe not endless, there’s probably some mathematical equation with an exponent involved that tells us how to calculate that.

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