Question 1

About what time does PI(4,5)P₂ disappear from a site of endocytosis? A)about the time the coated pit forms B)about the time the coated vesicle is pinched away from the plasma membrane C)when the ligand binds to the receptors D)well after the vesicle has pinched away from the plasma membrane E)as the coated pit rounds into a larger coated pit

Accepted Answer

PI(4,5)P₂ disappears from the site of endocytosis around the time when the coated vesicle is pinched away from the plasma membrane.

Question 2

Which of the following strategies is used by Mycobacterium tuberculosis,the bacterium responsible for tuberculosis,to avoid being destroyed by phagocytosis?
A)The bacterium crystallizes the enzymes in the phagolysosome.
B)The bacterium inhibits fusion of the phagosome with a lysosome.
C)The bacterium allows fusion with the lysosome,but neither the acidic pH nor the lysosomal enzymes can destroy it.
D)The bacterium produces proteins that destroy lysosomal membrane integrity so that the bacterium can escape into the cell cytosol.
E)The bacterium neutralizes the enzymes in the lysosome.

Accepted Answer

Mycobacterium tuberculosis is able to survive phagocytosis by inhibiting the fusion of the phagosome with a lysosome. This prevents the bacterium from being exposed to the acidic pH and lysosomal enzymes that would normally destroy it.

Question 3

Which of the following has not been identified as a phosphoinositide? A)PI(3)P B)PI(4)P C)PI(5)P D)PI(6)P E)PI(3,4)P₂

Accepted Answer

PI(6)P has not been identified as a phosphoinositide. All of the other options (A, B, C, and E) have been identified as phosphoinositides based on the number and position of their phosphate groups.

Question 4

The phosphorylated rings of phosphoinositides are recognized and bound by particular proteins.Where are the phosphorylated rings located?
A)They reside in the membrane interior.
B)They are found in lysosomes.
C)They reside at the membrane surface.
D)They reside inside the clathrin coat.
E)They reside inside the COPII-coat.

Accepted Answer

The phosphorylated rings of phosphoinositides are located at the membrane surface, where they can be recognized and bound by specific proteins.

Question 5

If you treated a macrophage with colchicine (a microtubular inhibitor),what would be likely to happen to the rate of phagocytosis? What would be likely to happen to the rate of phagocytosis if you treated the macrophage with an inhibitor of microfilament contractile activities?
A)Nothing would happen after colchicine exposure.The rate would rise after cytochalasin B exposure
B)The rate would drop after colchicine exposure.Nothing would happen after cytochalasin B exposure.
C)Nothing would happen after colchicine exposure.The rate would drop after cytochalasin B exposure.
D)The rate would rise after colchicine exposure.Nothing would happen after cytochalasin B exposure.
E)Nothing would happen after treatment with either inhibitor.

Accepted Answer

Microtubules are involved in the formation of pseudopodia, which are necessary for phagocytosis. Microfilaments are involved in the contractile activities that allow the macrophage to engulf the particle.

Question 6

The three-legged assembly of protein chains that makes up a clathrin molecule and that can assemble into a network of polygons resembling a honeycomb is called a(n)_____.
A)trigeminy
B)triskeleton
C)trigellium
D)triskelion
E)triskellium

Accepted Answer

The term described in the question is the triskelion, which is composed of three protein chains arranged in a three-legged structure. Therefore, the correct answer is D, triskelion. The other answer choices (trigeminy, triskeleton, trigellium, triskellium) do not accurately describe the structure of clathrin.

Question 7

Which of the following is a difference between the coats of COPII- and clathrin-coated vesicles?
A)The inner layer of adaptor proteins of COPII-coated vesicles overlap extensively,while those of clathrin-coated vesicles do not overlap.
B)The outer scaffold subunits of the clathrin lattice of coated vesicles overlap extensively,while those of the COPII lattice of coated vesicles do not overlap.
C)The outer scaffold subunits of the COPII lattice of coated vesicles overlap extensively,while those of the clathrin lattice of coated vesicles do not overlap.
D)The clathrin-coated vesicles have three distinct layers,while the COPII-coated vesicles have two distinct layers.

Accepted Answer

The outer scaffold subunits of the clathrin lattice of coated vesicles overlap extensively, while those of the COPII lattice of coated vesicles do not overlap. This means that the coats of COPII- and clathrin-coated vesicles differ in the way their outer scaffold subunits are arranged. COPII-coated vesicles have a more open lattice structure than clathrin-coated vesicles.

Question 8

Which phosphoinositide is localized at the TGN,secretory granules and synaptic vesicles? A)PI(4,5)P₂ B)PI(4)P C)PI(3,5)P₂ D)PI(3)P E)PI(5)P

Accepted Answer

PI(4)P is localized at the trans-Golgi network (TGN), secretory granules, and synaptic vesicles, playing a role in membrane trafficking and signaling.

Question 9

What helps to give different membrane compartments their own unique surface identity?
A)the different proteins contained within them
B)the different surface nucleotides in each one
C)the different shapes of the different membrane compartments
D)the degree of concentration of the contents of the membrane compartments

Accepted Answer

Different membrane compartments have their own unique surface identity due to the different proteins contained within them. Proteins on the surface of the membrane can function as receptors, channels, or enzymes, and the specific combination and arrangement of these proteins help to give each membrane compartment its distinct identity. The other options (B, C, and D) do not contribute as directly or significantly to surface identity as the proteins do.

Question 10

What drives the engulfment of particulate material by phagocytosis?
A)contractile activities of the actin-containing microfilaments that underlie the plasma membrane
B)contractile activities of the tubulin-containing microtubules that underlie the plasma membrane
C)contractile activities of the actin-containing microfilaments that underlie the mitochondrial membrane
D)contractile activities of the myosin-containing microfilaments that underlie the plasma membrane
E)contractile activities of the tubulin-containing microtubules that underlie the mitochondrial membrane

Accepted Answer

The engulfment of particulate material by phagocytosis is driven by the contractile activities of the actin-containing microfilaments that underlie the plasma membrane. These microfilaments are responsible for extending pseudopods around the material to be engulfed and then bringing them back together to form a phagosome. Once the phagosome is formed, it can then fuse with lysosomes for degradation of the engulfed material.

Question 11

The best-studied adaptors that participate in the formation of the coated pits and coated vesicles of clathrin-mediated endocytosis are the _____ adaptors.
A)COPII
B)GGA
C)AP2
D)clathrin
E)COPI

Accepted Answer

The AP2 adaptors are specifically involved in clathrin-mediated endocytosis, which involves the formation of coated pits and vesicles. The other adaptors listed are involved in different processes, such as COPII in protein transport from the endoplasmic reticulum to the Golgi and COPI in protein transport within the Golgi. GGA adaptors are involved in trafficking between the trans-Golgi network and endosomes. Clathrin itself is a structural protein involved in the formation of the clathrin coat around the vesicle.

Question 12

The inner leaflet of the plasma membrane contains elevated levels of PI(4,5)P₂,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like ______ and ______? A)AP3,dynamin B)AP2,dynamin C)TGN,dynamin D)TGN,dynamin. E)clathrin,dynamin

Accepted Answer

PI(4,5)P2 is crucial for recruiting AP2 and dynamin, which are key proteins in clathrin-mediated endocytosis.

Question 13

Lipid species like the phosphoinositides can have a dynamic regulatory role because _______.
A)it can be rapidly formed by enzymes localized at particular places within the cell
B)it can be rapidly formed by enzymes localized at particular times within the cell
C)it can be rapidly destroyed by enzymes localized at particular places within the cell
D)it can be rapidly destroyed by enzymes localized at particular times within the cell
E)All of these are correct.

Accepted Answer

All of the options given are correct. Lipid species like phosphoinositides can have a dynamic regulatory role because they can be rapidly formed by enzymes localized at specific places and times within the cell, and they can also be rapidly destroyed by enzymes localized at specific places and times within the cell. This dynamic regulation allows these lipids to act as signaling molecules and play critical roles in cellular processes such as membrane trafficking, cytoskeletal rearrangement, and cell signaling.

Question 14

Substances that enter the cell by receptor-mediated endocytosis bind receptors that collect in specialized domains of the plasma membrane called ______.
A)coated vesicles
B)coated pits
C)RME pits
D)gap junctions
E)tight junctions

Accepted Answer

Receptor-mediated endocytosis involves the binding of substances to receptors that are concentrated in coated pits of the plasma membrane. The coated pits then form vesicles that transport the substances into the cell.

Question 15

Which of the following strategies is used by Listeria monocytogenes,a bacterium that causes meningitis,to avoid being destroyed by a lysosome's fusion with the phagosome in which it was ingested?
A)The bacterium allows fusion with the lysosome,but the acidic pH cannot destroy it.
B)The bacterium inhibits fusion of the phagosome with a lysosome.
C)The bacterium allows fusion with the lysosome,but the lysosomal enzymes cannot destroy it.
D)The bacterium produces proteins that destroy lysosomal membrane integrity so that the bacterium can escape into the cell cytosol.
E)The bacterium neutralizes the enzymes in the lysosome.

Accepted Answer

Listeria monocytogenes produces listeriolysin O, a toxin that disrupts the lysosomal membrane, allowing the bacterium to escape into the cytosol before being destroyed.

Question 16

Which molecule below is a GTP-binding protein that is required for the release of a clathrin-coated vesicle from the membrane on which it was formed?
A)AP2
B)GGA
C)clathrin
D)dynamin
E)opsonin

Accepted Answer

Dynamin is a GTP-binding protein that is required for the release of a clathrin-coated vesicle from the membrane on which it was formed. AP2 and GGA are adaptor proteins involved in cargo selection and recruitment of clathrin, while clathrin itself forms the coat of the vesicle. Opsonin is not involved in clathrin-coated vesicle formation.

Question 17

The phosphorylated rings of phosphoinositides are recognized and bound by particular proteins.Where are the phosphorylated rings located?
A)They reside in the membrane interior.
B)They are found in lysosomes.
C)They reside at the membrane surface.
D)They reside inside the clathrin coat.
E)They reside inside the COPII-coat.

Accepted Answer

The phosphorylated rings of phosphoinositides reside at the membrane surface, where they can be recognized and bound by particular proteins.

Question 18

What types of molecules below can a cell internalize by receptor-mediated endocytosis?
A)hormones and growth factors
B)enzymes
C)bloode-borne proteins carrying certain nutrients
D)hormones and growth factors and enzymes
E)All of these are correct

Accepted Answer

All of the molecules mentioned (hormones and growth factors, enzymes, and blood-borne proteins carrying certain nutrients) can be internalized by receptor-mediated endocytosis. This is a mechanism by which cells can selectively take up specific molecules from their environment by using specialized receptors on their surface. The molecules bind to the receptors, triggering the formation of a clathrin-coated pit and ultimately the internalization of the receptor-ligand complex into the cell through an endocytic vesicle. This mechanism is important for nutrient uptake, signaling, and other cellular processes.

Question 19

What molecules do the AP2 adaptors of the clathrin coat connect?
A)GGA adaptors and clathrin molecules
B)the cytoplasmic tails of specific membrane receptors and clathrin molecules
C)the luminal tails of specific membrane receptors and clathrin molecules
D)the clathrin molecules and cargo molecules
E)cargo molecules and the cytoplasmic tails of specific membrane receptors

Accepted Answer

The answer of What molecules do the AP2 adaptors of...

Question 20

The inner leaflet of the plasma membrane contains elevated levels of _____,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like dynamin and AP2. A)PI(4,5)P₂ B)PI(4)P C)PI(3,5)P₂ D)PI(3,4)P₂ E)PI(5)P

Accepted Answer

PI(4,5)P2 (Phosphatidylinositol 4,5-bisphosphate) is known for its role in clathrin-mediated endocytosis, where it recruits proteins such as dynamin and AP2 to the plasma membrane.

Quiz 8: Cytoplasmic Membrane Systems: Structure, function, and Membrane Trafficking

About what time does PI(4,5) P₂ disappear from a site of endocytosis?

Which of the following strategies is used by Mycobacterium tuberculosis,the bacterium responsible for tuberculosis,to avoid being destroyed by phagocytosis?

Which of the following has not been identified as a phosphoinositide?

The phosphorylated rings of phosphoinositides are recognized and bound by particular proteins.Where are the phosphorylated rings located?

If you treated a macrophage with colchicine (a microtubular inhibitor) ,what would be likely to happen to the rate of phagocytosis? What would be likely to happen to the rate of phagocytosis if you treated the macrophage with an inhibitor of microfilament contractile activities?

The three-legged assembly of protein chains that makes up a clathrin molecule and that can assemble into a network of polygons resembling a honeycomb is called a(n) _____.

Which of the following is a difference between the coats of COPII- and clathrin-coated vesicles?

Which phosphoinositide is localized at the TGN,secretory granules and synaptic vesicles?

What helps to give different membrane compartments their own unique surface identity?

What drives the engulfment of particulate material by phagocytosis?

The best-studied adaptors that participate in the formation of the coated pits and coated vesicles of clathrin-mediated endocytosis are the _____ adaptors.

The inner leaflet of the plasma membrane contains elevated levels of PI(4,5) P₂,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like and ?

Lipid species like the phosphoinositides can have a dynamic regulatory role because _______.

Substances that enter the cell by receptor-mediated endocytosis bind receptors that collect in specialized domains of the plasma membrane called ______.

Which of the following strategies is used by Listeria monocytogenes,a bacterium that causes meningitis,to avoid being destroyed by a lysosome's fusion with the phagosome in which it was ingested?

Which molecule below is a GTP-binding protein that is required for the release of a clathrin-coated vesicle from the membrane on which it was formed?

The phosphorylated rings of phosphoinositides are recognized and bound by particular proteins.Where are the phosphorylated rings located?

What types of molecules below can a cell internalize by receptor-mediated endocytosis?

What molecules do the AP2 adaptors of the clathrin coat connect?

The inner leaflet of the plasma membrane contains elevated levels of _____,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like dynamin and AP2.

Quiz 8: Cytoplasmic Membrane Systems: Structure, function, and Membrane Trafficking

About what time does PI(4,5) P2 disappear from a site of endocytosis?

Which of the following strategies is used by Mycobacterium tuberculosis,the bacterium responsible for tuberculosis,to avoid being destroyed by phagocytosis?

Which of the following has not been identified as a phosphoinositide?

The phosphorylated rings of phosphoinositides are recognized and bound by particular proteins.Where are the phosphorylated rings located?

If you treated a macrophage with colchicine (a microtubular inhibitor) ,what would be likely to happen to the rate of phagocytosis? What would be likely to happen to the rate of phagocytosis if you treated the macrophage with an inhibitor of microfilament contractile activities?

The three-legged assembly of protein chains that makes up a clathrin molecule and that can assemble into a network of polygons resembling a honeycomb is called a(n) _____.

Which of the following is a difference between the coats of COPII- and clathrin-coated vesicles?

Which phosphoinositide is localized at the TGN,secretory granules and synaptic vesicles?

What helps to give different membrane compartments their own unique surface identity?

What drives the engulfment of particulate material by phagocytosis?

The best-studied adaptors that participate in the formation of the coated pits and coated vesicles of clathrin-mediated endocytosis are the _____ adaptors.

The inner leaflet of the plasma membrane contains elevated levels of PI(4,5) P2,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like ______ and ______?

Lipid species like the phosphoinositides can have a dynamic regulatory role because _______.

Substances that enter the cell by receptor-mediated endocytosis bind receptors that collect in specialized domains of the plasma membrane called ______.

Which of the following strategies is used by Listeria monocytogenes,a bacterium that causes meningitis,to avoid being destroyed by a lysosome's fusion with the phagosome in which it was ingested?

Which molecule below is a GTP-binding protein that is required for the release of a clathrin-coated vesicle from the membrane on which it was formed?

The phosphorylated rings of phosphoinositides are recognized and bound by particular proteins.Where are the phosphorylated rings located?

What types of molecules below can a cell internalize by receptor-mediated endocytosis?

What molecules do the AP2 adaptors of the clathrin coat connect?

The inner leaflet of the plasma membrane contains elevated levels of _____,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like dynamin and AP2.

About what time does PI(4,5) P₂ disappear from a site of endocytosis?

The inner leaflet of the plasma membrane contains elevated levels of PI(4,5) P₂,which plays an important role in the recruitment of proteins involved in clathrin-mediated endocytosis,like and ?