A small generic section of the primary structure of an α helix is given by − amino acid 1 − amino acid 2 − amino acid 3 − amino acid 4 − amino acid 5 − amino acid 6 − amino acid 7 − −amino acid1−amino acid2−amino acid3−amino acid4−amino acid5−amino acid6−amino acid7− Which amino acid residue's backbone forms a hydrogen bond with the backbone of the first ( 1 st ) (1st) residue