PayЕ 30-Which structure among the following represents an amide (protein) bond? A) —N=C=0 C-NH- -C-NH- C-0- 31-Which type of forces form the primary structure of a protein? 32-The two protein chains in insulin are held together by 33-Keratin, the protein of hair and skin, has extensive sections with which secondary structure? 34-The beta-pleated sheet is an example of 35-The type of bond that is most important in maintaining secondary structure of a protein is 36-All of the following are examples of fibrous proteins except A) wool. B) fingernails. C) skin. D) insulin. E) bones.