CHAPTER FIVE AMINO ACIDS PEPTIDES AND PROTEINS 1 Which of the following is a function of proteins A Defense B Metabolic regulation C Transport D Catalysis E All of the above are correct 2 The term protein refers to amino acid polymers with greater than amino acids Ans E A 10 B 20 C 50 D 70 E 90 Ans C A Glycine B Cysteine C 5 Hydroxyproline D Valine E Alanine Ans C A Alanine B Valine 3 Which of the following is a nonstandard amino acid 4 Which of the following is a heterocyclic amino acid Ans C 5 Which of the following is not a class of amino acid 6 Which of the following amino acids lacks a center of asymmetry 7 Given the following pK s what is the principal form of serine at pH 5 C Proline D Tyrosine E Cystine A Nonpolar and neutral B Polar and neutral C Acidic D Basic E Asymmetric Ans E A Alanine B Glycine C Valine D Isoleucine E Aspartic acid Ans B pKa1 2 21 pKa2 9 15 A B OH H H O H2C CH C O NH3 OH H O H2C CH C O NH3 H O H O C H2C CH NH3 O OH H O O H2C CH C O NH3 H2C CH NH2 O C H O C D E Ans E A 2 21 B 5 68 C 9 15 D 6 62 E 11 36 Ans B 8 Given the following pKa s the isoelectric point of serine is pK1 2 21 pK2 9 15 9 Consider the following dipeptide Which letter indicates a peptide bond A H N H H C H B H N C O H C H C E H O O C D A A B B C C D D E E Ans C A Primary B Secondary C Tertiary D Quaternary E Peptide Ans A A Primary B Secondary C Tertiary D Quaternary E Peptide 10 The amino acid sequence of a polypeptide is referred to as structure 11 The overall three dimensional structure of a polypeptide is referred to as structure 12 Invariant amino acids in a protein are presumed A To be unimportant in the structure and function of the protein B To be essential to the structure and function of the protein C Always to occur at the beginning of the amino acid sequence of an enzyme D Always to occur at the end of the amino acid sequence of an enzyme E To be part of the prosthetic group 13 pleated sheets are associated with what level of protein structure Ans C Ans B A Primary B Secondary C Tertiary D Quaternary E Superquaternary Ans B A Glycine B Alanine C Proline D Tyrosine E Serine Ans B 14 Which of the following amino acids would foster an helix 15 The Greek key is associated with which of the following A helix B Parallel pleated sheets C Antiparallel pleated sheets D Disulfide bridges E Salt bridges Ans C A Hydrophobic interactions B Electrostatic interactions C Hydrogen bonds D Covalent bonds E None of the above Ans E A Hydrogen bonds B Disulfide bridges C Hydrophobic interactions D Salt bridges E Both A and B are correct Ans C 16 Which of the following interactions do not stabilize tertiary structure 17 Detergents denature proteins by disrupting which of the following 18 Fibrous proteins typically have large amounts of A Helix B Pleated sheets C Disulfide bridges D Salt bridges E Both A and B are correct Ans E Ans E Ans B Ans A 19 The identity and arrangement of amino acids on the surface of a globular protein are important because they may A Interact to form specific binding cavities B Stabilize the tertiary structure of the protein C Bind regulatory molecules D Both A and C are correct E All of the above are correct 20 Which of the following statements regarding cooperative binding is true A Two or more proteins aid the binding of a ligand B The binding of one ligand aids the binding of a second ligand C The folding of part of a protein aids in the folding of the remainder of the protein D All proteins engage in cooperative binding E The binding of a cofactor to a protein aids in the binding of a ligand 21 Which of the following statements is true of the Bohr effect A Oxygen is delivered to cells in proportion to their needs B Binding of protons to hemoglobin molecules facilitates the binding of oxygen C Metabolic waste products bond to oxyhemoglobin D A and B are both true E All of the above are true 22 A polypeptide has a high pI value Which of the following amino acids are likely to be present 23 Structural proteins freeze large amounts of water Which of the following interactions is not likely to be involved in the binding of water 24 Why is the peptide bond stronger than the ester bond A Greater electronegativity of nitrogen B Greater electronegativity of oxygen C Resonance stabilization of the amide bond D Increased basicity of nitrogen E Size of the nitrogen atom compared to the oxygen atom 25 Which of the following amino acids would be classified as a nonstandard amino acid A Glycine B Serine C Valine D Aspartic acid E Arginine Ans E A Salt bridges B Hydrogen bonding C Hydrophilic interactions D Disulfide bridges E Both C and D are correct Ans D Ans C A Tyrosine B Lysine C Cystine D Glycine 26 Given that pK1 2 35 and pK2 9 69 for alanine What is its isoelectric point 27 When not at the terminal of a protein which of the following amino acids cannot contribute to the PI of a protein 28 When part of a polypeptide chain other than the N terminus which of the following amino acids can form a aldimines E Arginine Ans C A 9 69 B 2 34 C 6 02 D 12 03 E 7 00 Ans C A Arginine B Lysine C Cysteine D Tyrosine E Alanine Ans E A Glycine B Alanine C Proline D Histidine E Lysine Ans E 29 Collagen is classified as which of the following types of protein A Enzyme B Structural C Movement D Defense E Regulatory Ans B 30 A prosthetic group is a A Repair enzyme B Group other than an amino acid that is part of a protein C Group that generates the native form of a protein D Disulfide link E Group that reduces enzyme activity 31 The major component of the dry weight of cells is A Carbohydrate B Protein C Fats D Minerals E The major component will vary from organism to organism Ans B Ans B A 1020 B 2010 C 100 32 The total number of proteins that can be produced from any 10 amino acids is D 200 E 1010 Ans B 33 Schiff bases are also referred to as A Aldimines B Amines C Carbinolamines D Amino acids E Both A and C are correct Ans A 34 Which of the following amino …