Question 1

The shortest $\alpha$ helix segment in a protein that will span a membrane bilayer has about _____ amino acid residues.

Accepted Answer

A)  5 
B)  20 
C)  50 
D)  100 
E)  200 
A)  5 
B)  20 
C)  50 
D)  100 
E)  200

Question 2

The plasma membrane of an animal cell consists of 45% by weight of phospholipid and 55% protein. What is the mole ratio (moles of lipid/moles of protein) if the average molecular weight of phospholipids is 750 and the average molecular weight of membrane proteins is 50,000?

Accepted Answer

To calculate the mole ratio of phospholi

Question 3

You are trying to isolate an enzyme that catalyzes the conversion of A $\rightarrow$ B, and you have a sensitive assay for this enzyme. After lysing open the cells, you find that the activity is associated with the membrane fraction, not the soluble fraction (which you throw away). You then follow the procedure shown below. Explain the sudden re-occurrence of activity at the end of your protocol.

Accepted Answer

The answer of You are trying to isolate an enzyme...

Question 4

(a) Explain why phosphoglycerides are capable of spontaneously assembling into the bilayer structure found in biological membranes but triacylglycerols are not. (b) What are the forces that drive bilayer formation?

Accepted Answer

(a) Phosphoglycerides are capable of spo

Question 5

Describe the structure of a biological membrane as proposed by the fluid mosaic model. Indicate the positions and orientations of phospholipids, cholesterol, integral and peripheral membrane proteins, and the carbohydrate moieties of glycoproteins and glycolipids.

Accepted Answer

The fluid mosaic model describes the str

Question 6

If a monovalent cation is being imported into a cell in the absence of a concentration gradient (i.e., the concentration for the transported cation is equal on both sides of the membrane), what could you predict about $\Delta$Gt? Assume the transmembrane potential is 50mV (inside negative).

Accepted Answer

A)  The value of $\Delta$Gt will have a positive sign. 
B)  The value of$\Delta$Gt will have a negative sign. 
C)  The value of $\Delta$Gt will likely be close to zero. 
D)  It is impossible to predict anything about the value of $\Delta$Gt. 
A)  The value of $\Delta$Gt will have a positive sign. 
B)  The value of$\Delta$Gt will have a negative sign. 
C)  The value of $\Delta$Gt will likely be close to zero. 
D)  It is impossible to predict anything about the value of $\Delta$Gt.

Question 7

What is an amphipathic compound? Explain how such compounds contribute to the structure of biological membranes.

Accepted Answer

An amphipathic compound is a molecule th

Question 8

For the process of solute transport, the constant Kt is:

Accepted Answer

A)  analogous to Ka for ionization of a weak acid. 
B)  analogous to Km for an enzyme-catalyzed reaction. 
C)  analogous to Vmax for an enzyme reaction 
D)  proportional to the number of molecules of glucose transporter per cell. 
E)  the maximum rate of glucose transport. 
A)  analogous to Ka for ionization of a weak acid. 
B)  analogous to Km for an enzyme-catalyzed reaction. 
C)  analogous to Vmax for an enzyme reaction 
D)  proportional to the number of molecules of glucose transporter per cell. 
E)  the maximum rate of glucose transport.

Question 9

Which statement is FALSE regarding the major facilitator superfamily of transporters?

Accepted Answer

A)  These proteins are all secondary active transporters. 
B)  Both GLUT1 and lactose permease belong to this family. 
C)  These proteins contain two domains within the membrane. 
D)  These proteins contain 12 or 14 transmembrane $\alpha$ helices 
A)  These proteins are all secondary active transporters. 
B)  Both GLUT1 and lactose permease belong to this family. 
C)  These proteins contain two domains within the membrane. 
D)  These proteins contain 12 or 14 transmembrane $\alpha$ helices

Question 10

What kind of bond can link a palmitoyl anchor to a polypeptide?

Accepted Answer

A)  an ester bond to an internal serine 
B)  an amide bond to a glycine 
C)  a thioester to a cysteine 
D)  an ester bond to the C-terminus. 
E)  both an ester bond to an internal serine and a thioester to a cysteine 
A)  an ester bond to an internal serine 
B)  an amide bond to a glycine 
C)  a thioester to a cysteine 
D)  an ester bond to the C-terminus. 
E)  both an ester bond to an internal serine and a thioester to a cysteine

Question 11

What kind of bond can link a prenyl anchor to a polypeptide?

Accepted Answer

A)  an ester bond to an internal serine 
B)  an amide bond to a glycine 
C)  a thioester to a cysteine 
D)  an ester bond to the C-terminus 
E)  a thioether bond to a cysteine side chain 
A)  an ester bond to an internal serine 
B)  an amide bond to a glycine 
C)  a thioester to a cysteine 
D)  an ester bond to the C-terminus 
E)  a thioether bond to a cysteine side chain

Question 12

What are the principle features of the fluid mosaic model of membranes?

Accepted Answer

The Fluid Mosaic Model is a widely accep

Question 13

Which step is NOT involved in neurotransmitter release at a synapse?

Accepted Answer

A)  creation of a fusion pore 
B)  hemifusion induced by zipping and lateral tension on the bilayers 
C)  v-SNARE binding to t-SNARE 
D)  pore widening and release of neurotransmitter 
E)  flippase-mediated movement of phosphatidylserine from the inner to the outer leaflet 
A)  creation of a fusion pore 
B)  hemifusion induced by zipping and lateral tension on the bilayers 
C)  v-SNARE binding to t-SNARE 
D)  pore widening and release of neurotransmitter 
E)  flippase-mediated movement of phosphatidylserine from the inner to the outer leaflet

Question 14

ABC transporters are NOT known to facilitate moving:

Accepted Answer

A)  cancer drugs out of cancer cells. 
B)  antibiotics out of bacteria. 
C)  membrane lipids from the inner leaflet to the outer leaflet. 
D)  chloride ions in the lung. 
E)  vitamin E into lipocytes. 
A)  cancer drugs out of cancer cells. 
B)  antibiotics out of bacteria. 
C)  membrane lipids from the inner leaflet to the outer leaflet. 
D)  chloride ions in the lung. 
E)  vitamin E into lipocytes.

Question 15

A hydropathy plot is used to:

Accepted Answer

A)  determine the water-solubility of a protein. 
B)  deduce the quaternary structure of a membrane protein. 
C)  determine the water content of a native protein. 
D)  extrapolate for the true molecular weight of a membrane protein. 
E)  predict whether a given protein sequence contains membrane-spanning segments. 
A)  determine the water-solubility of a protein. 
B)  deduce the quaternary structure of a membrane protein. 
C)  determine the water content of a native protein. 
D)  extrapolate for the true molecular weight of a membrane protein. 
E)  predict whether a given protein sequence contains membrane-spanning segments.

Question 16

Distinguish between simple diffusion (SD), facilitated diffusion (FD), and active transport (AT) across a membrane for the following questions. (More than one may be true.)
(a) Which processes are energy dependent?
(b) Which processes need some kind of carrier protein(s)?
(c) Which processes can be saturated by substrate?
(d) Which processes can establish a concentration gradient?
(e) How much energy does it take to transport an uncharged substrate in, if its starting inside concentration is 10-fold greater than outside?

Accepted Answer

(a) Which processes are energy dependent

Question 17

The type of membrane transport that uses ion gradients as the energy source is:

Accepted Answer

A)  facilitated diffusion 
B)  passive transport. 
C)  primary active transport. 
D)  secondary active transport. 
E)  simple diffusion. 
A)  facilitated diffusion 
B)  passive transport. 
C)  primary active transport. 
D)  secondary active transport. 
E)  simple diffusion.

Question 18

Movement of water across membranes is facilitated by proteins called:

Accepted Answer

A)  annexins. 
B)  aquaporins. 
C)  hydropermeases. 
D)  selectins. 
E)  transportins. 
A)  annexins. 
B)  aquaporins. 
C)  hydropermeases. 
D)  selectins. 
E)  transportins.

Question 19

Syndecans are proteoglycans that have glycosaminoglycans attached to the N-terminal domain, a single transmembrane helix and a C-terminal domain that can be phosphorylated. What type of membrane proteins are these?

Accepted Answer

A)  Type I 
B)  Type II 
C)  Type III 
D)  Type IV 
E)  Type V 
A)  Type I 
B)  Type II 
C)  Type III 
D)  Type IV 
E)  Type V

Question 20

Which statement about caveolin is FALSE?

Accepted Answer

A)  Caveolin is an integral membrane protein. 
B)  Caveolin induces outward membrane curvature. 
C)  Caveolin is palmitoylated. 
D)  Caveolin associates with cholesterol rich regions. 
E)  Caveolin is involved in membrane trafficking and cellular signaling. 
A)  Caveolin is an integral membrane protein. 
B)  Caveolin induces outward membrane curvature. 
C)  Caveolin is palmitoylated. 
D)  Caveolin associates with cholesterol rich regions. 
E)  Caveolin is involved in membrane trafficking and cellular signaling.

Exam 11: Biological Membranes and Transport

The shortest α\alphaα helix segment in a protein that will span a membrane bilayer has about _____ amino acid residues.

The plasma membrane of an animal cell consists of 45% by weight of phospholipid and 55% protein. What is the mole ratio (moles of lipid/moles of protein) if the average molecular weight of phospholipids is 750 and the average molecular weight of membrane proteins is 50,000?

(a) Explain why phosphoglycerides are capable of spontaneously assembling into the bilayer structure found in biological membranes but triacylglycerols are not. (b) What are the forces that drive bilayer formation?

Describe the structure of a biological membrane as proposed by the fluid mosaic model. Indicate the positions and orientations of phospholipids, cholesterol, integral and peripheral membrane proteins, and the carbohydrate moieties of glycoproteins and glycolipids.

If a monovalent cation is being imported into a cell in the absence of a concentration gradient (i.e., the concentration for the transported cation is equal on both sides of the membrane), what could you predict about Δ\DeltaΔ Gt? Assume the transmembrane potential is 50mV (inside negative).

What is an amphipathic compound? Explain how such compounds contribute to the structure of biological membranes.

For the process of solute transport, the constant Kt is:

Which statement is FALSE regarding the major facilitator superfamily of transporters?

What kind of bond can link a palmitoyl anchor to a polypeptide?

What kind of bond can link a prenyl anchor to a polypeptide?

What are the principle features of the fluid mosaic model of membranes?

Which step is NOT involved in neurotransmitter release at a synapse?

ABC transporters are NOT known to facilitate moving:

A hydropathy plot is used to:

The type of membrane transport that uses ion gradients as the energy source is:

Movement of water across membranes is facilitated by proteins called:

Syndecans are proteoglycans that have glycosaminoglycans attached to the N-terminal domain, a single transmembrane helix and a C-terminal domain that can be phosphorylated. What type of membrane proteins are these?

Which statement about caveolin is FALSE?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biosignaling

Bioenergetics and Biochemical Reaction Types

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Oxidative Phosphorylation and Photophosphorylation

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

The shortest $\alpha$ helix segment in a protein that will span a membrane bilayer has about _____ amino acid residues.

If a monovalent cation is being imported into a cell in the absence of a concentration gradient (i.e., the concentration for the transported cation is equal on both sides of the membrane), what could you predict about $\Delta$ G_t? Assume the transmembrane potential is 50mV (inside negative).

For the process of solute transport, the constant K_t is: