So the axis of rotation along which that alpha helix actually forms runs along the x axis in this direction. So this is the beginning of our polypeptide and this is the end. So we see that in this case, we go into the board, then we come out of the board, we go into the board, out of the board, we go into the board, out of the board, we go into the board, out of the board, and so forth. So the screw sense of our alpha helix basically describes the directionality of rotation about the axis of rotation for that particular alpha helix. Now, what do we mean by that? Well, if this is the axis of rotation, and if we look at the axis of rotation and we examine the directionality of that rotating alpha helix, the rotating polypeptide chain.