 The first simple vanilla amino acid I like to use is alanine it actually has a real side chain but it's a methane it's nothing special we don't have to worry about the side chain but it is a real amino acid with everything I showed you. Glycine, glycine is even simpler. Yes it is but there's one complication with glycine it's not really a complication but do you see that the cytine is just a hydrogen so it has two hydrogens and that means that glycine is actually not chiral there is no L and D forms of glycine because that requires four different bonds here that also means that it's super flexible which is great in many ways but it's this flexibility means that you're going to be paying a lot of entropy if you try to put this in structures and if you pay that entropy that means that it's not necessarily going to be so happy in those structures in particular not in alpha helices so it is important it does occur here and there but if you need a common amino acid that has no strong preference for either state I'd prefer to look at alanine. The obvious way to compare this is to look at the Ramachandran diagrams this is a typical Ramachandran diagram that could be pretty much any residue and in that case alanine is a great example do you see that you have those two big regions and maybe a small region that corresponded to that extra helix this one is glycine there are many more regions where the glycine can exist in the sense that there are not too many steric clashes but that does not mean that glycine will necessarily be happier because glycine would be happiest if it could be out insolvent and use all its flexibility without paying and the interpreter is that always bad no because in some cases if I need if I've done a secondary structure element and then I need to quickly go back I need to take a very tight turn then there's not going to be a lot of room and glycine is actually great to have in these turns so here we have on the lower end here we have a chain coming in and then I need to go back and I want to make a very quick turn but this would mean that the side chain here would be pointing inwards to the turn so for larger amino acids here I would need to make this turn larger but with glycine it's possible to have these super tight turns that virtually instantly go back and then we're also forming a hydrogen bond here in the middle so glycine when I see glycine in the structure in a sequence it can actually be an indication that we might have a turn there and a long term time ago this was used to predict turns and think of the restructure