Protein: How our body makes protein

Protein: How our body makes protein


Hi, this is Neily on Nutrition. Before we move on to the third macronutrient, fats and lipids, I wanted to finish up with something called protein synthesis. Remember we talked the other day about all of the important functions protein does. Well, we have to make those in the body, right? And that’s what protein synthesis is. As a reminder when we eat protein, they break down into individual amino acids. Those amino acids, there are 20 of them and 9 of them are essential, so they go into an amino acid pool and then they are called upon when needed to make the proteins. This is what happens and just to let you know this illustration is a very simplified illustration of what is happening, it gets the point across. Okay, so this is all happening in the cell. I also just drew the parts of the cell that are specific to what’s happening with proteins, and that’s the nucleus and ribosomes. So here, I’ve drawn a part of the nucleus where we have the DNA. Now the DNA is your genetic material and that contains the coding information for all of the hundreds of thousands of different proteins at the body makes, so what happens is that when we need to make a protein, a piece of the DNA creates a template and we make a copy of that template. That copy leaves the nucleus and that’s called mRNA or messenger RNA. The DNA never leaves the nucleus always stays there, but the copy leaves and that mRNA attaches to a ribosome. Think of the ribosome as the protein factory of the cell. So it attaches here and what happens is we start to make our protein one amino acid at a time. Actually 40 to 100 can be added at any given second, but just to illustrate here. We’ve got one amino acid, for example valine as is an individual amino acid and we are going to add histidine onto the valine. This is called a dipeptide when we have two amino acids, and the link between them is called a peptide bond. We’re going to add a third amino acid, now we have what we call a tripeptide when we added leucine onto this. Now most amino acids are hundreds of amino acids long, and they’re called polypeptides. That’s what’s happening here — we add one amino acid and the way they get to the ribosome is by these things right here, called transfer RNA. There’s thousands of these and they each carry an individual amino acid to the ribosome and release and start to build this protein strand. Here we have our valine, and then we’ve got our histidine, and then this chain starts to grow. Then we’ve got our leucine, so you can see the change starting to grow and on and on and on. Ultimately, we’re going to have this long strand of amino acids. Once the list is complete, then the strand will be released and the mRNA will be degraded. Then we have our protein and other things happen, but I’m going to go into that detail. It’s a lot more complicated than that but this is a very simplified explanation just to show you what’s happening when we’re making the proteins in the body. So we’re making our proteins — that list is very specific and it’s always in that same exact sequence every single time. So there you have a little bit more about protein, and I look forward to talking to you tomorrow as we move on to fats and lipids. Thanks for watching Neily on Nutrition and we’ll see you in tomorrow’s video. Thanks for watching.

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