And this is always true for the alpha helix. So it's the NH group of one amino acid that interacts with the co group of the amino acid that is found four units ahead of that amino acid. And the reason this takes place is because these are the groups that are found in closest proximity and are able to interact strongly. Now let's move on to the beta pleated sheets. We see that in the alpha helix we have this helical directionality of our polypeptide. But in the beta pleated sheets, these polymers are linear.