Question 1

Mediated transport or diffusion will ultimately result in the concentration of diffusing substance being the same on both sides of the membrane.

Accepted Answer

A) True 
 B)False  False

Question 2

In an aqueous environment the hydrocarbon tails of lipids tend to associate by entropy-driven ________ and by Van der Waals interactions.

Accepted Answer

hydrophobic effects

Question 3

Sphingomyelin contains a fatty acid linked by an ________ bond and phosphocholine linked via the C-3 hydroxyl group of sphingosine.

Accepted Answer

amide

Question 4

Integral membrane proteins can be inserted into the membrane and folded into the normal 3D structure during translation.

Accepted Answer

A) True 
 B)False

Question 5

Which of the following is unlikely to be a characteristic of a membrane protein?

Accepted Answer

A)  Largely hydrophobic transmembrane segments 
B)  α-helical membrane-spanning motifs. 
C)  Covalently attached lipid moities 
D)  Symmetric orientation across the membrane 
E)  β-sheet membrane-spanning motifs 
A)  Largely hydrophobic transmembrane segments 
B)  α-helical membrane-spanning motifs. 
C)  Covalently attached lipid moities 
D)  Symmetric orientation across the membrane 
E)  β-sheet membrane-spanning motifs

Question 6

Lipid rafts are small long-lived structures that respond to stimuli to transiently associate with each other to form larger raft platforms.

Accepted Answer

A) True 
 B)False

Question 7

Linolenic acid has cis double bonds with the formula CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH. Write out the abbreviated systematic numbering for this fatty acid.

Accepted Answer

The answer of Linolenic acid has cis double bonds with...

Question 8

Which of the following statements is FALSE?

Accepted Answer

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 C. 
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. 
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 C. 
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.

Question 9

Passive facilitated cotransport can move some substrate across a membrane against its concentration gradient.

Accepted Answer

A) True 
 B)False

Question 10

Which of following lipids can be a major component of biological membranes?

Accepted Answer

A)  Phosphatidic acid 
B)  Phosphatidylcholine 
C)  Phosphatidylinositol 
D)  Cholesterol 
E)  B and D 
A)  Phosphatidic acid 
B)  Phosphatidylcholine 
C)  Phosphatidylinositol 
D)  Cholesterol 
E)  B and D

Question 11

Raft platforms in membranes have functional roles in cell signaling and sorting of proteins into specific ________ in the cell.

Accepted Answer

The answer of Raft platforms in membranes have functional roles...

Question 12

Action potentials are propagated along a nerve axon by sequentially opening and closing a series of voltage-gated potassium and sodium channels.

Accepted Answer

A) True 
 B)False

Question 13

Which of the following statements about biological membranes is FALSE?

Accepted Answer

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 often require a specialized enzyme to facilitate movement across (flipping) the membrane. 
E)  They are often organized into smaller regions of specific function. 
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 often require a specialized enzyme to facilitate movement across (flipping) the membrane. 
E)  They are often organized into smaller regions of specific function.

Question 14

Active transport can move a substance across a membrane ________ its concentration gradient.

Accepted Answer

The answer of Active transport can move a substance across...

Question 15

The sodium-glucose cotransport system is an example of:

Accepted Answer

A)  an antiport transporter. 
B)  passive transport. 
C)  facilitated transport. 
D)  an ATP-dependent transporter. 
E)  none of the above. 
A)  an antiport transporter. 
B)  passive transport. 
C)  facilitated transport. 
D)  an ATP-dependent transporter. 
E)  none of the above.

Question 16

The rate of nonmediated diffusion tends to increase as the ________ character of the diffusing substance increases.

Accepted Answer

The answer of The rate of nonmediated diffusion tends to...

Question 17

Saturated fatty acids are different to unsaturated fatty acids because they:

Accepted Answer

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. 
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.

Question 18

Which of the following mechanisms is responsible for the selectivity of aquaporins for water?

Accepted Answer

A)  Size exclusion 
B)  Electrostatic repulsion 
C)  Dynamic hydrogen bonding 
D)  Prevention of ion gradient formation 
E)  All of the above 
A)  Size exclusion 
B)  Electrostatic repulsion 
C)  Dynamic hydrogen bonding 
D)  Prevention of ion gradient formation 
E)  All of the above

Question 19

Digitoxin can act as a short term cardiac stimulant by inhibiting the Na+-K+ pump.

Accepted Answer

A) True 
 B)False

Question 20

Which of the following is NOT relevant to facilitated transport across biological membranes?

Accepted Answer

A)  An ionophore is a carrier protein that increases the permeability of a membrane to ions. 
B)  Some permeases can transport their substrates in both directions. 
C)  A symport will transport two molecules in the same direction across a membrane. 
D)  ATP hydrolysis is required. 
E)  An antiport will move substrates in opposite directions across a membrane. 
A)  An ionophore is a carrier protein that increases the permeability of a membrane to ions. 
B)  Some permeases can transport their substrates in both directions. 
C)  A symport will transport two molecules in the same direction across a membrane. 
D)  ATP hydrolysis is required. 
E)  An antiport will move substrates in opposite directions across a membrane.

Exam 10: Lipids, Membranes, and Cellular Transport

Mediated transport or diffusion will ultimately result in the concentration of diffusing substance being the same on both sides of the membrane.

In an aqueous environment the hydrocarbon tails of lipids tend to associate by entropy-driven ________ and by Van der Waals interactions.

Sphingomyelin contains a fatty acid linked by an ________ bond and phosphocholine linked via the C-3 hydroxyl group of sphingosine.

Integral membrane proteins can be inserted into the membrane and folded into the normal 3D structure during translation.

Which of the following is unlikely to be a characteristic of a membrane protein?

Lipid rafts are small long-lived structures that respond to stimuli to transiently associate with each other to form larger raft platforms.

Linolenic acid has cis double bonds with the formula CH3CH2CH=CHCH2CH=CHCH2CH=CH(CH2)7COOH. Write out the abbreviated systematic numbering for this fatty acid.

Which of the following statements is FALSE?

Passive facilitated cotransport can move some substrate across a membrane against its concentration gradient.

Which of following lipids can be a major component of biological membranes?

Raft platforms in membranes have functional roles in cell signaling and sorting of proteins into specific ________ in the cell.

Action potentials are propagated along a nerve axon by sequentially opening and closing a series of voltage-gated potassium and sodium channels.

Which of the following statements about biological membranes is FALSE?

Active transport can move a substance across a membrane ________ its concentration gradient.

The sodium-glucose cotransport system is an example of:

The rate of nonmediated diffusion tends to increase as the ________ character of the diffusing substance increases.

Saturated fatty acids are different to unsaturated fatty acids because they:

Which of the following mechanisms is responsible for the selectivity of aquaporins for water?

Digitoxin can act as a short term cardiac stimulant by inhibiting the Na+-K+ pump.

Which of the following is NOT relevant to facilitated transport across biological membranes?

Biochemistry and the Language of Chemistry

The Chemical Foundation of Life: Weak Interactions in an Aqueous Environment

The Energetics of Life

Nucleic Acids

Introduction to Proteins: the Primary Level of Protein Structure

The Three-Dimensional Structure of Proteins

Protein Function and Evolution

Enzymes: Biological Catalysts

Carbohydrates: Sugars, Saccharides, Glycans

Chemical Logic of Metabolism

Carbohydrate Metabolism: Glycolysis, Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

The Citric Acid Cycle

Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

Photosynthesis

Lipid Metabolism

Interorgan and Intracellular Coordination of Energy Metabolism in Vertebrates

Amino Acid and Nitrogen Metabolism

Nucleotide Metabolism

Mechanisms of Signal Transduction

Genes, Genomes, and Chromosomes

DNA Replication

DNA Repair, Recombination, and Rearrangement

Transcription and Post-Transcriptional Processing

Information Decoding: Translation and Post-Translational Protein Processing

Regulation of Gene Expression

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