Protein Structure

by Jason Amores Sumpter
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in this video, we're going to introduce protein structure. And so proteins have a hierarchy of structure that's organized into four levels of structure that air conveniently labeled primary, secondary, tertiary and Quaternary levels of protein structure. And so notice that the text that we have up above for each of the four levels of structure corresponds with the image that we have down below for each of the four levels of protein structure. And so the very first level of protein structure is the primary level of structure, which we can abbreviate with a one here. And so the primary level of protein structure specifically refers to the types, the quantity and the specific order or sequence of amino acids in the chain. And so, by changing either the types, the quantity or the order of amino acids in the chain, then we can change the primary level of protein structure. And so the primary level of protein structure is really, really, really important because it determines all of the other levels of structure, including the secondary, tertiary and quaternary levels of structure. And so when we take a look at our image down below, over here on the left hand side notice that each of these circles represent amino acids. And so we have this long amino acid chain here and the specific types, quantity and order or sequence of these amino acids in this long chain eyes going to be the primary protein structure so we can fill in primary down below over here now the second level of protein structures, of course, the secondary level of protein structure, so we can put a two over here, and this is referring specifically to the formation of either Alfa Hillis ease or beta sheets in the protein backbone. And so when we take a look at our image down below at the secondary protein structure, notice that the protein backbone can either take a winding shaped like what we see here, which would be the Alfa Helix. Or the protein backbone could take more of a zigzag shaped like what we see down here, which is the beta sheet structure. So this is more of a zigzag, whereas this is more of a winding structure, and so we could say that secondary protein structure is going to be the formation of either Alfa he'll is's or beta sheets in the protein backbone, and so this leads us to the tertiary level of protein structure, which of course can be symbolized here with a three. And so the tertiary level of protein structure is specifically referring to the overall three D shape, or three dimensional shape of the poly peptide chain. And so, if we take a look at our image down below, notice that the long poly peptide chain over here, when it forms Alfa Hillis is in beta sheets. It can fold onto itself to create this complex, overall three dimensional structure. And so the tertiary protein protein structure. It's specifically referring to the overall three dimensional shape and so embedded within the overall three dimensional shape. You can see the Alfa Healy sees here that air in blue, and you can see the beta sheets that air in red over here. And so these levels of structure they build onto each other. And so this leads us to the fourth and final level of protein structure, which is the Quaternary level of protein structure, which, of course, could be symbolized with the four, and this is specifically referring to win Multiple poly peptide chains are going to associate with each other toe form a single functional protein. And so when we take a look at our image down below, notice that there are two poly peptide chains here we have this lighter gray poly peptide chain over here, and then we have this darker poly peptide chain over here. And when you have these two separate poly peptide chains that come together and associate to form a single functional protein, that is what we refer to as the Quaternary protein structure. So it's when multiple amino acid chains come together. And so this year concludes our introduction to protein structure, and we'll be able to talk a little bit more about protein structure in our next lesson video, so I'll see you all there.