Protein Power: Translation
In Part 3 of this series on DNA, Everyday Einstein explains how our cells take instructions from messenger RNA and use them to build the proteins essential for our bodies.
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In Part 1 of my Protein Power series, I talked about how RNA works and how it differs from DNA. Then in Part 2 we looked at how our cells modify RNA in order to create messenger RNA or mRNA, a molecule which contains instructions for making protein. This week, we’ll finish up this series by looking at how our cells take those instructions and use them to build the protein.
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Leaving the Nucleus
When we last left our RNA molecule, it had just received two tickets it needed to survive life outside of the nucleus: a 5’ cap and a poly-adenosine tail. Now our RNA can escape the confines of the cell’s nucleus through one of the many nuclear pores which dot the walls.
Once outside the nucleus, the mRNA is free to dock with a ribosome. A ribosome is a very large, very complicated mass of proteins and RNA that has the exciting job of translating the code embedded in mRNA molecules into proteins. This is such an exciting job that most mammals have millions of ribosomes floating around in every cell, just looking for mRNA molecules to attach to.
Ribosomes have two parts, cleverly called the “large sub-unit” and “small sub-unit.” They clamp onto the mRNA molecule like two halves of a clamshell. Once the ribosome is firmly attached, the actual process of translation can begin.
As amazing as ribosomes are, just like any other complicated factory, they can’t make anything without regular shipments of raw materials. The raw materials needed for marking proteins are amino acids. Every protein in your body is made up of a long string of amino acids stuck together with a special chemical bond called a peptide bond. However, in order to string these amino acids together, the ribosome first needs to find them.
There are hundreds of different kinds of amino acids, but only 23 different ones are currently known to be used in protein building. You might have heard the phrase “essential amino acids” before, as in “Choco-coated sugar bombs provide your child with all essential amino acids!”
While your body is able to synthesize most of the types of amino acids it needs, there are 9 amino acids needed for protein synthesis which your body can’t synthesize. So the only way for your ribosomes to get access to those varieties are through the foods you eat.