Biochem 2: Exam 1 Mastery Questions AND COMPLETE SOLUTIONS
Saturated fatty acids are different to unsaturated fatty acids 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 Correct Answer: 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 saturated 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 Correct Answer: 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 acids 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. Correct Answer: E. B and D
Spingomyelin contains a fatty acid linked by an _________ bond and phosphocholine linked via
the C-3 hydroxyl group of sphingosine. Correct Answer: Amide
Which of the following is unlikely to be a characteristic of a membrane protein?
A. Largely hydrophobic transmembrane segments
, B. α-helical membrane-spanning motifs
C. Covalently attached lipid motifs
D. Symmetric orientation across the membrane
E. β-sheet membrane-spanning motifs Correct Answer: D. Symmetric orientation across the
membrane
In an aqueous environment, the hydrocarbon tails of lipids tend to associate by entropy-driven
________ and by Van der Waals interactions. Correct Answer: Hydrophobic effects
Raft platforms in membranes have functional roles in cell signaling and sorting of proteins into
specific ________ in the cell. Correct Answer: 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 proteins 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 Correct Answer: B. Lipids
and proteins move laterally at approximately the same rate within the membrane
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 Correct Answer: 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. Correct Answer: False.
Saturated fatty acids are different to unsaturated fatty acids 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 Correct Answer: 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 saturated 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 Correct Answer: 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 acids 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. Correct Answer: E. B and D
Spingomyelin contains a fatty acid linked by an _________ bond and phosphocholine linked via
the C-3 hydroxyl group of sphingosine. Correct Answer: Amide
Which of the following is unlikely to be a characteristic of a membrane protein?
A. Largely hydrophobic transmembrane segments
, B. α-helical membrane-spanning motifs
C. Covalently attached lipid motifs
D. Symmetric orientation across the membrane
E. β-sheet membrane-spanning motifs Correct Answer: D. Symmetric orientation across the
membrane
In an aqueous environment, the hydrocarbon tails of lipids tend to associate by entropy-driven
________ and by Van der Waals interactions. Correct Answer: Hydrophobic effects
Raft platforms in membranes have functional roles in cell signaling and sorting of proteins into
specific ________ in the cell. Correct Answer: 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 proteins 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 Correct Answer: B. Lipids
and proteins move laterally at approximately the same rate within the membrane
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 Correct Answer: 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. Correct Answer: False.
