Question 1

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 2

Compare the structure and activity of a membrane transport protein that transports a polar substance across a membrane with a typical soluble enzyme.How are transporter and enzyme similar? How are they different?

Accepted Answer

Both proteins have domains that specific

Question 3

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 4

Which of the following statements 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.

Question 5

Which of the following is not a step 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 6

(a)When relatively high concentrations of fatty acids are suspended in water,they form structures known as ________.
(b)When relatively high concentrations of membrane phospholipids are dissolved in water,they form structures known as ________.
(c)Why are the structures listed in your answers to (a)and (b)above energetically favored?

Accepted Answer

(a)micelles.
(b)bilayers.
(c)Micelles ar

Question 7

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

Accepted Answer

All three are families of integral membr

Question 8

In one catalytic cycle,the Na+/K+ ATPase transporter transports:

Accepted Answer

A) 2 Na+ out,3 K+ in,and converts 1 ATP to ADP + Pi. 
B) 3 Na+ out,2 K+ in,and converts 1 ATP to ADP + Pi. 
C) 3 Na+ in,2 K+ out,and converts 1 ATP to ADP + Pi. 
D) 1 Na+ out,1 K+ in,and converts 1 ATP to ADP + Pi. 
E) 2 Na+ out,3 K+ in,and converts 1 ADP + Pi to ATP. 
A) 2 Na+ out,3 K+ in,and converts 1 ATP to ADP + Pi. 
B) 3 Na+ out,2 K+ in,and converts 1 ATP to ADP + Pi. 
C) 3 Na+ in,2 K+ out,and converts 1 ATP to ADP + Pi. 
D) 1 Na+ out,1 K+ in,and converts 1 ATP to ADP + Pi. 
E) 2 Na+ out,3 K+ in,and converts 1 ADP + Pi to ATP.

Question 9

Facilitated diffusion through a biological membrane is:

Accepted Answer

A) driven by a difference of solute concentration. 
B) driven by ATP. 
C) endergonic. 
D) generally irreversible. 
E) not specific with respect to the substrate 
A) driven by a difference of solute concentration. 
B) driven by ATP. 
C) endergonic. 
D) generally irreversible. 
E) not specific with respect to the substrate

Question 10

(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): Triacylglycerols have three fatty a

Question 11

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

The ratio of moles lipid/moles protein i

Question 12

Explain why nonpolar compounds are generally able to diffuse across biological membranes without the aid of a specific transport system.

Accepted Answer

A nonpolar compound is more soluble in n

Question 13

The fluidity of a lipid bilayer will be increased by:

Accepted Answer

A) decreasing the number of unsaturated fatty acids. 
B) decreasing the temperature. 
C) increasing the length of the alkyl chains. 
D) increasing the temperature. 
E) substituting 18:0 (stearic acid)in place of 18:2 (linoleic acid). 
A) decreasing the number of unsaturated fatty acids. 
B) decreasing the temperature. 
C) increasing the length of the alkyl chains. 
D) increasing the temperature. 
E) substituting 18:0 (stearic acid)in place of 18:2 (linoleic acid).

Question 14

(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)The forces that hold integral membran

Question 15

Which of these statements 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 16

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 17

Glucose transport into erythrocytes is an example of:

Accepted Answer

A) active transport. 
B) antiport. 
C) electrogenic uniport 
D) facilitated diffusion. 
E) symport. 
A) active transport. 
B) antiport. 
C) electrogenic uniport 
D) facilitated diffusion. 
E) symport.

Question 18

Which of these statements about facilitated diffusion across a membrane is true?

Accepted Answer

A) A specific membrane protein lowers the activation energy for movement of the solute through the membrane. 
B) It can increase the size of a transmembrane concentration gradient of the diffusing solute. 
C) It is impeded by the solubility of the transported solute in the nonpolar interior of the lipid bilayer. 
D) It is responsible for the transport of gases such as O2,N2,and CH4 across biological membranes. 
E) The rate is not saturable by the transported substrate. 
A) A specific membrane protein lowers the activation energy for movement of the solute through the membrane. 
B) It can increase the size of a transmembrane concentration gradient of the diffusing solute. 
C) It is impeded by the solubility of the transported solute in the nonpolar interior of the lipid bilayer. 
D) It is responsible for the transport of gases such as O2,N2,and CH4 across biological membranes. 
E) The rate is not saturable by the transported substrate.

Question 19

Membrane proteins:

Accepted Answer

A) are sometimes covalently attached to lipid moieties. 
B) are sometimes covalently attached to carbohydrate moieties. 
C) are composed of the same 20 amino acids found in soluble proteins. 
D) diffuse laterally in the membrane unless they are anchored 
E) have all of the properties listed above. 
A) are sometimes covalently attached to lipid moieties. 
B) are sometimes covalently attached to carbohydrate moieties. 
C) are composed of the same 20 amino acids found in soluble proteins. 
D) diffuse laterally in the membrane unless they are anchored 
E) have all of the properties listed above.

Question 20

(a)List three different major components of eukaryotic membranes.
(b)When a preparation of mitochondrial membranes was treated with high salt (0.5 M NaCl),it was observed that 40% of the total protein in this preparation was solubilized.What kind of membrane proteins are in this soluble extract,and what forces normally hold them to the membrane? 
(c)What kind of proteins constitute the insoluble 60%,and what forces hold these proteins in the membrane?

Accepted Answer

(a)Phospholipids,sterols,proteins (integ

Exam 11: Biological Membranes and Transport

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

Compare the structure and activity of a membrane transport protein that transports a polar substance across a membrane with a typical soluble enzyme.How are transporter and enzyme similar? How are they different?

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. )

Which of the following statements about caveolin is false?

Which of the following is not a step involved in neurotransmitter release at a synapse?

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

In one catalytic cycle,the Na+/K+ ATPase transporter transports:

Facilitated diffusion through a biological membrane is:

(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?

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?

Explain why nonpolar compounds are generally able to diffuse across biological membranes without the aid of a specific transport system.

The fluidity of a lipid bilayer will be increased by:

(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 of these statements is generally true of integral membrane proteins?

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

Glucose transport into erythrocytes is an example of:

Which of these statements about facilitated diffusion across a membrane is true?

Membrane proteins:

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

Recombinant Dna Technology

Lipids

Biosignaling

Principles of Bioenergetics

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

Integration and Hormonal Regulation of Mammalian Metabolism

Genes and Chromosomes

Dna Metabolism

Rna Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

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. )

In one catalytic cycle,the Na⁺/K⁺ ATPase transporter transports:

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