Question 1

Which of the following are integral membrane proteins that do not contain a transmembrane $\alpha$ helix?

Accepted Answer

A)  Band 3 
B)  Glycophorins 
C)  Glycosylphosphatidylinositol (GPI)-anchored proteins 
D)  Spectrins 
A)  Band 3 
B)  Glycophorins 
C)  Glycosylphosphatidylinositol (GPI)-anchored proteins 
D)  Spectrins C

Question 2

Describe a role or function for coated pits in the process of receptor-mediated endocytosis.

Accepted Answer

Receptors and ligands (cargo) cluster into coated pits and are subsequently internalized and recycled.

Question 3

Detergents are used to solubilize membranes because they are dual molecules possessing both hydrophobic and hydrophilic portions. Why are they also used as cleaning reagents (to clean, for example, clothes and dishes)?

Accepted Answer

Detergents are used as cleansers because the hydrophobic portions of the molecules bind to hydrophobic substances, such as an oil stain, while the hydrophilic portions bind to water, and the detergent/dirt complex is subsequently washed away in the rinse. Simply trying to remove the stain with water doesn't work because the hydrophilic water molecules do not interact with the lipid molecules in the oil stain.

Question 4

Shibere is a temperature-sensitive mutant in the protein dynamin in the fruit fly Drosophila. Why do flies fall out of the air when shifted to the nonpermissive temperature?

Accepted Answer

Flying requires coordinated muscle movem

Question 5

Why is dissociation of ligands from their receptors in endosomes an important feature of receptor-mediated endocytosis?

Accepted Answer

The dissociation of ligands from their r

Question 6

Defects in the human LDL receptor can cause the disease hypercholesterolemia.

Accepted Answer

A) True 
 B)False

Question 7

Why does incubation of cells with NH3 cause the selective osmotic swelling of endosomes and lysosomes and not of other organelles in the cell?

Accepted Answer

NH₃ can cross membranes, while NH₄⁺, the pr

Question 8

Cystic fibrosis (CF) is the most common inherited disease of Caucasians. It is due to mutations in an ABC transporter, the cystic fibrosis transmembrane conductance regulator (CFTR), which is a Cl- and bicarbonate channel. Why have efforts at gene therapy to correct CF concentrated on the lungs when CF affects other tissues as well?

Accepted Answer

The cells lining the surface of the lung

Question 9

Which of the following is not involved in receptor-mediated endocytosis?

Accepted Answer

A)  Clathrin 
B)  Adaptor proteins 
C)  Internalization signals 
D)  Pseudopodia 
A)  Clathrin 
B)  Adaptor proteins 
C)  Internalization signals 
D)  Pseudopodia

Question 10

Why are most ion channels gated?

Accepted Answer

Most ion channels are ligand- or voltage

Question 11

The outer membrane of mitochondria is the major site where porins are found in animal cells.

Accepted Answer

A) True 
 B)False

Question 12

Brown and Goldstein discovered the mechanism of cholesterol uptake by studying fibroblasts from patients with which disease?

Accepted Answer

A)  Chronic fatigue syndrome 
B)  Familial hypercholesterolemia 
C)  Lupus erythematosus 
D)  Cystic fibrosis 
A)  Chronic fatigue syndrome 
B)  Familial hypercholesterolemia 
C)  Lupus erythematosus 
D)  Cystic fibrosis

Question 13

Although Na+ is smaller than K+, its passage through the K+ channel is blocked by the _______ filter.

Accepted Answer

A)  CO2 
B)  negativity 
C)  positivity 
D)  selectivity 
A)  CO2 
B)  negativity 
C)  positivity 
D)  selectivity

Question 14

Phagocytosis involves movement of the cell surface by

Accepted Answer

A)  actin-based motility. 
B)  microtubule-based motility. 
C)  clathrin-based vesicle formation. 
D)  dynamin-based vesicle formation. 
A)  actin-based motility. 
B)  microtubule-based motility. 
C)  clathrin-based vesicle formation. 
D)  dynamin-based vesicle formation.

Question 15

How does the structure of a transport protein such as a glucose transporter create an aqueous environment in which glucose may be transported across the plasma membrane?

Accepted Answer

A glucose transporter has mult

Question 16

What are integral membrane proteins?

Accepted Answer

They are proteins th

Question 17

Cholesterol is present in the membranes of all

Accepted Answer

A)  cells. 
B)  eukaryotic cells. 
C)  animal cells. 
D)  plant cells. 
A)  cells. 
B)  eukaryotic cells. 
C)  animal cells. 
D)  plant cells.

Question 18

The Na+ and K+ ion gradients across the plasma membrane are produced primarily by the

Accepted Answer

A)  permeability of these ions across the lipid bilayer. 
B)  ratio of these ions in the blood. 
C)  action of the Na+-K+ pump. 
D)  flow of these ions through voltage-gated channels. 
A)  permeability of these ions across the lipid bilayer. 
B)  ratio of these ions in the blood. 
C)  action of the Na+-K+ pump. 
D)  flow of these ions through voltage-gated channels.

Question 19

Bacteria, fungi, and plants use a gradient of _______ ions across their plasma membranes to drive transport of other molecules into the cells.

Accepted Answer

A)  Na+ 
B)  K+ 
C)  H+ 
D)  Ca2+ 
A)  Na+ 
B)  K+ 
C)  H+ 
D)  Ca2+

Question 20

The pH of endosomes and lysosomes is

Accepted Answer

A)  acidic. 
B)  alkaline. 
C)  neutral. 
D)  unknown. 
A)  acidic. 
B)  alkaline. 
C)  neutral. 
D)  unknown.

Which of the following are integral membrane proteins that do not contain a transmembrane $\alpha$ helix?

Describe a role or function for coated pits in the process of receptor-mediated endocytosis.

Detergents are used to solubilize membranes because they are dual molecules possessing both hydrophobic and hydrophilic portions. Why are they also used as cleaning reagents (to clean, for example, clothes and dishes)?

Shibere is a temperature-sensitive mutant in the protein dynamin in the fruit fly Drosophila. Why do flies fall out of the air when shifted to the nonpermissive temperature?

Why is dissociation of ligands from their receptors in endosomes an important feature of receptor-mediated endocytosis?

Defects in the human LDL receptor can cause the disease hypercholesterolemia.

Why does incubation of cells with NH₃ cause the selective osmotic swelling of endosomes and lysosomes and not of other organelles in the cell?

Which of the following is not involved in receptor-mediated endocytosis?

Why are most ion channels gated?

The outer membrane of mitochondria is the major site where porins are found in animal cells.

Brown and Goldstein discovered the mechanism of cholesterol uptake by studying fibroblasts from patients with which disease?

Although Na⁺ is smaller than K⁺, its passage through the K⁺ channel is blocked by the _______ filter.

Phagocytosis involves movement of the cell surface by

How does the structure of a transport protein such as a glucose transporter create an aqueous environment in which glucose may be transported across the plasma membrane?

What are integral membrane proteins?

Cholesterol is present in the membranes of all

The Na⁺ and K⁺ ion gradients across the plasma membrane are produced primarily by the

Bacteria, fungi, and plants use a gradient of _______ ions across their plasma membranes to drive transport of other molecules into the cells.

The pH of endosomes and lysosomes is

An Overview of Cells and Cell Research

Molecules and Membranes

Bioenergetics and Metabolism

Fundamentals of Molecular Biology

Genomics, Proteomics, and Systems Biology

Genes and Genomes

Replication, Maintenance, and Rearrangements of Genomic Dna

RNA Synthesis and Processing

Transcriptional Regulation and Epigenetics

Protein Synthesis, Processing, and Regulation

The Nucleus

Protein Sorting and Transport

Mitochondria, Chloroplasts, and Peroxisomes

The Cytoskeleton and Cell Movement

Cell Walls, the Extracellular Matrix, and Cell Interactions

Cell Signaling

The Cell Cycle

Cell Death and Cell Renewal

Cancer

Filters

Exam 15: The Plasma Membrane

Which of the following are integral membrane proteins that do not contain a transmembrane α\alphaα helix?

Describe a role or function for coated pits in the process of receptor-mediated endocytosis.

Detergents are used to solubilize membranes because they are dual molecules possessing both hydrophobic and hydrophilic portions. Why are they also used as cleaning reagents (to clean, for example, clothes and dishes)?

Shibere is a temperature-sensitive mutant in the protein dynamin in the fruit fly Drosophila. Why do flies fall out of the air when shifted to the nonpermissive temperature?

Why is dissociation of ligands from their receptors in endosomes an important feature of receptor-mediated endocytosis?

Defects in the human LDL receptor can cause the disease hypercholesterolemia.

Why does incubation of cells with NH3 cause the selective osmotic swelling of endosomes and lysosomes and not of other organelles in the cell?

Which of the following is not involved in receptor-mediated endocytosis?

Why are most ion channels gated?

The outer membrane of mitochondria is the major site where porins are found in animal cells.

Brown and Goldstein discovered the mechanism of cholesterol uptake by studying fibroblasts from patients with which disease?

Although Na+ is smaller than K+, its passage through the K+ channel is blocked by the _______ filter.

Phagocytosis involves movement of the cell surface by

How does the structure of a transport protein such as a glucose transporter create an aqueous environment in which glucose may be transported across the plasma membrane?

What are integral membrane proteins?

Cholesterol is present in the membranes of all

The Na+ and K+ ion gradients across the plasma membrane are produced primarily by the

Bacteria, fungi, and plants use a gradient of _______ ions across their plasma membranes to drive transport of other molecules into the cells.

The pH of endosomes and lysosomes is

An Overview of Cells and Cell Research

Molecules and Membranes

Bioenergetics and Metabolism

Fundamentals of Molecular Biology

Genomics, Proteomics, and Systems Biology

Genes and Genomes

Replication, Maintenance, and Rearrangements of Genomic Dna

RNA Synthesis and Processing

Transcriptional Regulation and Epigenetics

Protein Synthesis, Processing, and Regulation

The Nucleus

Protein Sorting and Transport

Mitochondria, Chloroplasts, and Peroxisomes

The Cytoskeleton and Cell Movement

Cell Walls, the Extracellular Matrix, and Cell Interactions

Cell Signaling

The Cell Cycle

Cell Death and Cell Renewal

Cancer

Filters

Which of the following are integral membrane proteins that do not contain a transmembrane $\alpha$ helix?

Why does incubation of cells with NH₃ cause the selective osmotic swelling of endosomes and lysosomes and not of other organelles in the cell?

Although Na⁺ is smaller than K⁺, its passage through the K⁺ channel is blocked by the _______ filter.

The Na⁺ and K⁺ ion gradients across the plasma membrane are produced primarily by the