Chapter 12 Lipids and Cell Membranes 4 5 Which of the following statements is consistent with the structure of biological membranes? A) All membrane proteins are integral and associate with the hydrophobic region of the membrane. B) Both proteins and lipids readily undergo transverse("flip-flop")diffusion from the inside to the outside of the membrane C) Membranes are symmetric. D) The membrane lipids self-assemble to form the lipid bilayer. E) A biological membrane consists of proteins sandwiched between two layers of lipids, which is referred to as a lipid bilayer. Ans:D Section:12.3 6 Which of the following is not correct concerning the structure given? 1 HH CH2-O-C(CH2)14CH3 CH3(CH2)C=C(CH2)C-O-CH 0 CH2-OPOCH2CH2N(CH3)3 0- A It is a component of biological membranes. B) It is amphipathic. C) It is a sphingolipid. D) It is a phosphoglyceride. E)It is phosphatidyl choline. Ans:D Section:12.2 7 How do the membranes of archaea differ from bacteria and eukaryotes? A) The lipids do not contain a carboxylic acid ester,but instead have an ether link to the glycerol. B) The alkyl chains are branched C) The stereochemistry of the central carbon of glycerol is inverted. D) a and c. E)a,b,and c. Ans:E Section:12.2 8 Carbohydrate residues attached to the membrane lipids are A)always positioned on the intracellular side of the membrane. B) always positioned on the inside center of the bilayer. C)always positioned on the extracellular side of the membrane. D) always positioned equally on both sides of the membrane. E)also covalently attached to membrane proteins Ans:C Section:12.2 9 What force(s)stabilize(s)the lipid bilayers? A)van der Waals interactions B) electrostatic and hydrogen bonding between the polar heads and surrounding water C) covalent bonds between the lipid tails D) covalent bonds between the lipids and membrane proteins E)a and b Ans:D Section:12.3Chapter 12 Lipids and Cell Membranes 4 5 Which of the following statements is consistent with the structure of biological membranes? A) All membrane proteins are integral and associate with the hydrophobic region of the membrane. B) Both proteins and lipids readily undergo transverse (“flip-flop”) diffusion from the inside to the outside of the membrane. C) Membranes are symmetric. D) The membrane lipids self-assemble to form the lipid bilayer. E) A biological membrane consists of proteins sandwiched between two layers of lipids, which is referred to as a lipid bilayer. Ans: D Section: 12.3 6 Which of the following is not correct concerning the structure given? + C H 2 C H C H 2 O C(C H 2 )14C H 3 O C H 3 (C H 2 )7C C(C H 2 )7C O O H H O PO C H 2C H 2N (C H 3 )3 O O - A) It is a component of biological membranes. B) It is amphipathic. C) It is a sphingolipid. D) It is a phosphoglyceride. E) It is phosphatidyl choline. Ans: D Section: 12.2 7 How do the membranes of archaea differ from bacteria and eukaryotes? A) The lipids do not contain a carboxylic acid ester, but instead have an ether link to the glycerol. B) The alkyl chains are branched. C) The stereochemistry of the central carbon of glycerol is inverted. D) a and c. E) a, b, and c. Ans: E Section: 12.2 8 Carbohydrate residues attached to the membrane lipids are A) always positioned on the intracellular side of the membrane. B) always positioned on the inside center of the bilayer. C) always positioned on the extracellular side of the membrane. D) always positioned equally on both sides of the membrane. E) also covalently attached to membrane proteins. Ans: C Section: 12.2 9 What force(s) stabilize(s) the lipid bilayers? A) van der Waals interactions B) electrostatic and hydrogen bonding between the polar heads and surrounding water C) covalent bonds between the lipid tails D) covalent bonds between the lipids and membrane proteins E) a and b Ans: D Section: 12.3