Biochem 2: Exam 1 Mastery Questions Saturated fatty acids are different to unsaturated fatty acid s because they: A. have an even number of carbon atoms B. have short hydrophobic tails C. have no C=C double bonds D. exhibit free rotation about the carbon carbon bonds in the hydrocarbon tail E. mostly have cis double bonds - C. have no C=C double bonds Which of the following statements is FALSE? A. The longer the chain length of a saturated fatty acid, the higher the melting temperature B. The difference in melting temperature between a sat urated fatty acid and an unsaturated fatty acid with the same chain length is only a few degrees Celsius. C. Most types of fat in many animals is used in energy production D. Some unsaturated fatty acids are liquid at physiological temperatures E. Fatty acids exist in the anionic form (RCOO -) at physiological pH - B. The difference in melting temperature between a saturated fatty acid and an unsaturated fatty acid with the same chain length is only a few degrees Celsius. Explanation: Unsaturated fatty a cids tend to be more liquid because they cannot be packed as tightly as saturated fatty acids. Which of the following lipids can be a major component of biological membranes? A. Phosphatic acid B. Phosphatidylcholine C. Phosphatidylinositol D. Cholesterol E. B and D. - E. B and D Spingomyelin contains a fatty acid linked by an _________ bond and phosphocholine linked via the C -3 hydroxyl group of sphingosine. - Amide Which of the following is unlikely to be a characteristic of a membrane pr otein? A. Largely hydrophobic transmembrane segments Biochem 2: Exam 1 Mastery Questions B. α-helical membrane -spanning motifs C. Covalently attached lipid motifs D. Symmetric orientation across the membrane E. β-sheet membrane -spanning motifs - D. Symmetric orientation across the membr ane In an aqueous environment, the hydrocarbon tails of lipids tend to associate by entropy -
driven ________ and by Van der Waals interactions. - Hydrophobic effects Raft platforms in membranes have functional roles in cell signaling and sorting of protei ns into specific ________ in the cell. - Organelles Which of the following statements about biological membranes is FALSE? A. They are composed of a mixture of lipids and proteins in which lateral diffusion of components is possible B. Lipids and protei ns move laterally at approximately the same rate within the membrane C. The faces of biological membranes are distinct and usually different in both composition and structure. D. Phospholipids require a specialized enzyme to facilitate movement across (flipping) the membrane E. They are often organized into smaller regions of specific function - B. Lipids and proteins move laterally at approximately the same rate within the me mbrane Explanation: Lipids move laterally within the membrane faster than proteins True or False: Integral membrane proteins can be inserted into the membrane and folded into the normal 3D structure during translation - True. Explanation: Folding and insertion happens simultaneously True or False: Lipid rafts are small long -lived structures that respond to stimuli to transiently associate with each other to form larger raft platforms. - False.
driven ________ and by Van der Waals interactions. - Hydrophobic effects Raft platforms in membranes have functional roles in cell signaling and sorting of protei ns into specific ________ in the cell. - Organelles Which of the following statements about biological membranes is FALSE? A. They are composed of a mixture of lipids and proteins in which lateral diffusion of components is possible B. Lipids and protei ns move laterally at approximately the same rate within the membrane C. The faces of biological membranes are distinct and usually different in both composition and structure. D. Phospholipids require a specialized enzyme to facilitate movement across (flipping) the membrane E. They are often organized into smaller regions of specific function - B. Lipids and proteins move laterally at approximately the same rate within the me mbrane Explanation: Lipids move laterally within the membrane faster than proteins True or False: Integral membrane proteins can be inserted into the membrane and folded into the normal 3D structure during translation - True. Explanation: Folding and insertion happens simultaneously True or False: Lipid rafts are small long -lived structures that respond to stimuli to transiently associate with each other to form larger raft platforms. - False.
