22-53 Do iron and zinc ions play role in protein structure? If so, what is the role for either or both?

Which of the following describes the primary structure of proteins? a. The collective shape assumed by all of the chains in a protein containing multiple chains. b. The folding of an individual protein molecule. c. The regular repeated shape of the protein molecules backbone. d. The sequence of amino acids bonded together by peptide bonds.

What element is always present in proteins that is seldom present in carbohydrates and lipids?

For the tripeptide SerArgIle which amino acid residues a. are hydrophilic b. are hydrophobic c. possess polar neutral R groups d. participate in two amide linkages

21-85 Which of the following statements is (are) consistent with what is known about membranes? (a) A membrane consists of a layer of proteins sandwiched between two layers of lipids. (b) The compositions of the inner and outer lipid layers are the same in any individual membrane. (c) Membranes contain glycolipids and glycoproteins. (d) Lipid bilayers are an important component of membranes. (e) Covalent bonding takes place between lipids and proteins in most membranes.

22-104 Why is collagen not a very good source of dietary protein?

. How many possible primary structures exist for a small polypeptide containing four individual amino acids?

22-49 Based on your knowledge of the chemical properties of amino acid side chains, suggest a substitution for leucine in the primary structure of a protein that would probably not change the character of the protein very much.

21-90 To what extent do lipids and carbohydrates play structural roles in living organisms? Do these roles differ in plants and in animals?