So let's begin with the anti parallel case and let's discuss how the bonding actually takes place within the anti parallel beta pleated sheets. Now, because we essentially have one of these chains running in this direction and the other one is reversed, we see that these groups actually line up with one another perfectly. And what that means is if we examine this amino acid here and this amino acid here, their groups that are able to interact line up perfectly. So we have this hydrogen accepting group that interacts with this hydrogen donating group on the other amino acid. And here we have this hydrogen donating group that interacts with this hydrogen accepting group of the other opposing amino acid. So in the antiparallel beta sheets, we see that the NH and the co groups of an amino acid on one strand interact with the Co and NH groups of the opposing amino acid on the other strand.