Question 1

Which statement is NOT true about the chloride-bicarbonate exchanger (AE)?

Accepted Answer

A)  The AE protein increases the rate of bicarbonate transport across the membrane. 
B)  The AE protein uses ATP as an energy source to drive bicarbonate transport. 
C)  The AE protein transports chloride ions across the membrane. 
D)  The AE protein is classified as an anti-porter. 
E)  The AE protein spans the membrane at least 12 times. 
A)  The AE protein increases the rate of bicarbonate transport across the membrane. 
B)  The AE protein uses ATP as an energy source to drive bicarbonate transport. 
C)  The AE protein transports chloride ions across the membrane. 
D)  The AE protein is classified as an anti-porter. 
E)  The AE protein spans the membrane at least 12 times.

Question 2

Describe two different ways a plant can adjust the components of its cell membranes to keep them as fluid as possible on a cold winter morning.

Accepted Answer

One way a plant can adjust the component

Question 3

Integrins are:

Accepted Answer

A)  membrane proteins that are involved in ion transport. 
B)  membrane proteins that are involved in sugar transport. 
C)  membrane proteins that mediate cell adhesion. 
D)  proteins of the extracellular matrix that bind to cell surface proteins. 
E)  proteins that are found at the membrane-cytoplasm interface. 
A)  membrane proteins that are involved in ion transport. 
B)  membrane proteins that are involved in sugar transport. 
C)  membrane proteins that mediate cell adhesion. 
D)  proteins of the extracellular matrix that bind to cell surface proteins. 
E)  proteins that are found at the membrane-cytoplasm interface.

Question 4

An integral membrane protein can be extracted with:

Accepted Answer

A)  a buffer of alkaline or acid pH. 
B)  a chelating agent that removes divalent cations. 
C)  a solution containing detergent. 
D)  a solution of high ionic strength. 
E)  hot water. 
A)  a buffer of alkaline or acid pH. 
B)  a chelating agent that removes divalent cations. 
C)  a solution containing detergent. 
D)  a solution of high ionic strength. 
E)  hot water.

Question 5

A protein is found to extend all the way through the membrane of a cell. Describe this protein in terms of the location of particular types of amino acid side chains in its structure and its ability to move within the membrane.

Accepted Answer

The protein that extends all the way thr

Question 6

Which transporter will move lipids from the cytosolic leaflet to the outer leaflet of a plasma membrane?

Accepted Answer

A)  a flippase 
B)  a floppase 
C)  a scramblase 
D)  both a flippase and a floppase 
E)  both a floppase and a scramblase 
A)  a flippase 
B)  a floppase 
C)  a scramblase 
D)  both a flippase and a floppase 
E)  both a floppase and a scramblase

Question 7

Which enzymes are NOT involved in moving phospholipids from one leaflet to another?

Accepted Answer

A)  flippases that move phosphatidylethanolamine and phosphatidylserine 
B)  floppases that move phospholipids from the cytosolic leaflet to the extracellular leaflet 
C)  flip-floppases that allow phospholipids to move back and forth between the inner and outer leaflets 
D)  scramblases that allow phospholipids to move down their concentration gradient 
E)  phosphatidylinositol transfer proteins that play a role in lipid signaling 
A)  flippases that move phosphatidylethanolamine and phosphatidylserine 
B)  floppases that move phospholipids from the cytosolic leaflet to the extracellular leaflet 
C)  flip-floppases that allow phospholipids to move back and forth between the inner and outer leaflets 
D)  scramblases that allow phospholipids to move down their concentration gradient 
E)  phosphatidylinositol transfer proteins that play a role in lipid signaling

Question 8

Which statement is TRUE for passive transport across a biological membrane?

Accepted Answer

A)  Passive transport is driven by a solute electrochemical gradient. 
B)  Passive transport is driven by ATP. 
C)  Passive transport is irreversible. 
D)  Passive transport is driven by both a solute electrochemical gradient ATP. 
E)  Passive transport is driven by a solute electrochemical gradient and is irreversible. 
A)  Passive transport is driven by a solute electrochemical gradient. 
B)  Passive transport is driven by ATP. 
C)  Passive transport is irreversible. 
D)  Passive transport is driven by both a solute electrochemical gradient ATP. 
E)  Passive transport is driven by a solute electrochemical gradient and is irreversible.

Question 9

Which structure describes an integral membrane protein containing a $\beta$barrel?

Accepted Answer

A)  maltoporin 
B)  aquaporin 
C)  E. coli OmpF 
D)  both maltoporin and E. coli OmpF 
E)  both maltoporin and aquaporin 
A)  maltoporin 
B)  aquaporin 
C)  E. coli OmpF 
D)  both maltoporin and E. coli OmpF 
E)  both maltoporin and aquaporin

Question 10

A plant breeder has developed a new frost-resistant variety of tomato that contains higher levels of unsaturated fatty acids in membrane lipids than those found in standard tomato varieties. However, when temperatures climb above 95 °F, this frost-resistant variety dies, whereas the standard variety continues to grow. Provide a likely explanation of the biochemical basis of increased tolerance to cold and increased susceptibility to heat of this new tomato variety.

Accepted Answer

The likely explanation for the biochemic

Question 11

Describe a hydropathy plot for a hypothetical integral membrane protein with 3 transmembrane segments and containing 190 amino acids.

Accepted Answer

A hydropathy plot is a graph that shows

Question 12

The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is Mr 50,000 and the average lipid is 750.)

Accepted Answer

A)  1 
B)  50 
C)  200 
D)  10,000 
E)  50,000 
A)  1 
B)  50 
C)  200 
D)  10,000 
E)  50,000

Question 13

(a) What kinds of forces or bonds anchor an integral membrane protein in a biological membrane? (b) What forces hold a peripheral membrane protein to the membrane? (c) What might one do to solubilize each of the two types of membrane proteins?

Accepted Answer

(a) Integral membrane proteins are ancho

Question 14

Which transporter will move lipids from the outer leaflet to the cytosolic leaflet of a plasma membrane?

Accepted Answer

A)  a flippase 
B)  a floppase 
C)  a scramblase 
D)  both a flippase and a floppase 
E)  both a flippase and a scramblase 
A)  a flippase 
B)  a floppase 
C)  a scramblase 
D)  both a flippase and a floppase 
E)  both a flippase and a scramblase

Question 15

Which statement about the composition of membranes is TRUE?

Accepted Answer

A)  All biological membranes contain cholesterol. 
B)  Free fatty acids are major components of all membranes. 
C)  The inner and outer membranes of mitochondria have different protein compositions. 
D)  The lipid composition of all membranes of eukaryotic cells is essentially the same. 
E)  The lipid:protein ratio varies from about 1:4 to 4:1. 
A)  All biological membranes contain cholesterol. 
B)  Free fatty acids are major components of all membranes. 
C)  The inner and outer membranes of mitochondria have different protein compositions. 
D)  The lipid composition of all membranes of eukaryotic cells is essentially the same. 
E)  The lipid:protein ratio varies from about 1:4 to 4:1.

Question 16

Which statement is TRUE concerning the chloride-bicarbonate exchanger?

Accepted Answer

A)  This transporter is electrogenic. 
B)  The exchanger is a passive antiporter. 
C)  This protein is involved in carbon dioxide transport in the blood stream. 
D)  The exchanger is a passive antiporter, and this protein is involved in carbon dioxide transport in the blood stream. 
E)  This transporter is electrogenic, and the exchanger is a passive antiporter. 
A)  This transporter is electrogenic. 
B)  The exchanger is a passive antiporter. 
C)  This protein is involved in carbon dioxide transport in the blood stream. 
D)  The exchanger is a passive antiporter, and this protein is involved in carbon dioxide transport in the blood stream. 
E)  This transporter is electrogenic, and the exchanger is a passive antiporter.

Question 17

Which process does NOT require a protein facilitator?

Accepted Answer

A)  simple diffusion 
B)  ionophore-mediated diffusion 
C)  a primary active uniport 
D)  a passive antiporter 
E)  both simple diffusion and ionophore-mediated diffusion 
A)  simple diffusion 
B)  ionophore-mediated diffusion 
C)  a primary active uniport 
D)  a passive antiporter 
E)  both simple diffusion and ionophore-mediated diffusion

Question 18

What are the similarities and differences between integrins, cadherins, and selectins?

Accepted Answer

Integrins, cadherins, and selectins are

Question 19

Which statement is generally TRUE of integral membrane proteins?

Accepted Answer

A)  The secondary structure in the transmembrane region consists solely of $\alpha$ helices or $\beta$sheets. 
B)  The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides. 
C)  They are unusually susceptible to degradation by trypsin. 
D)  They can be removed from the membrane with high salt or mild denaturing agents. 
E)  They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer. 
A)  The secondary structure in the transmembrane region consists solely of $\alpha$ helices or $\beta$sheets. 
B)  The domains that protrude on the cytoplasmic face of the plasma membrane nearly always have covalently attached oligosaccharides. 
C)  They are unusually susceptible to degradation by trypsin. 
D)  They can be removed from the membrane with high salt or mild denaturing agents. 
E)  They undergo constant rotational motion that moves a given domain from the outer face of a membrane to the inner face and then back to the outer.

Question 20

The bacterium E. coli can grow at 20 °C or at 40 °C. At which growth temperature would you expect the membrane phospholipids to have a higher ratio of saturated to unsaturated fatty acids, and why?

Accepted Answer

At 20 °C, you would expect the membrane

Exam 11: Biological Membranes and Transport

Which statement is NOT true about the chloride-bicarbonate exchanger (AE)?

Describe two different ways a plant can adjust the components of its cell membranes to keep them as fluid as possible on a cold winter morning.

Integrins are:

An integral membrane protein can be extracted with:

A protein is found to extend all the way through the membrane of a cell. Describe this protein in terms of the location of particular types of amino acid side chains in its structure and its ability to move within the membrane.

Which transporter will move lipids from the cytosolic leaflet to the outer leaflet of a plasma membrane?

Which enzymes are NOT involved in moving phospholipids from one leaflet to another?

Which statement is TRUE for passive transport across a biological membrane?

Which structure describes an integral membrane protein containing a β\betaβ barrel?

Describe a hydropathy plot for a hypothetical integral membrane protein with 3 transmembrane segments and containing 190 amino acids.

The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is Mr 50,000 and the average lipid is 750.)

(a) What kinds of forces or bonds anchor an integral membrane protein in a biological membrane? (b) What forces hold a peripheral membrane protein to the membrane? (c) What might one do to solubilize each of the two types of membrane proteins?

Which transporter will move lipids from the outer leaflet to the cytosolic leaflet of a plasma membrane?

Which statement about the composition of membranes is TRUE?

Which statement is TRUE concerning the chloride-bicarbonate exchanger?

Which process does NOT require a protein facilitator?

What are the similarities and differences between integrins, cadherins, and selectins?

Which statement is generally TRUE of integral membrane proteins?

The bacterium E. coli can grow at 20 °C or at 40 °C. At which growth temperature would you expect the membrane phospholipids to have a higher ratio of saturated to unsaturated fatty acids, and why?

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

Which structure describes an integral membrane protein containing a $\beta$ barrel?

The inner (plasma) membrane of E. coli is about 75% lipid and 25% protein by weight. How many molecules of membrane lipid are there for each molecule of protein? (Assume that the average protein is M_r 50,000 and the average lipid is 750.)