Chapter 15 Quiz

Which organelle receives proteins and lipids from the endoplasmic reticulum, modifies them, and then dispatches them to other destinations in the cell? Choose one: A. Golgi apparatus B. nucleus C. mitochondrion D. peroxisome E. endosome

A. Golgi apparatus

As a polypeptide is being translocated across the membrane of the endoplasmic reticulum, a stop-transfer sequence can halt the process. What eventually becomes of this stop-transfer sequence? Choose one: A. It forms an α-helical membrane-spanning segment of the protein. B. It remains in the cytosol. C. It is cleaved from the protein. D. It is translocated into the lumen of the endoplasmic reticulum. E. It stops protein synthesis and causes the ribosome to be released back to the cytosol.

A. It forms an α-helical membrane-spanning segment of the protein.

What is the function of cargo in receptor-mediated endocytosis? A. Molecules packaged into vesicle for transport B. Captures the correct cargo molecules C. Mediates contact between the receptor and another component D. Shapes the forming vesicle

A. Molecules packaged into vesicle for transport

Which proteins play a central role in the fusion of a vesicle with a target membrane? Choose one: A. SNAREs B. tethering proteins C. adaptin D. Rab proteins E. clathrin

A. SNAREs

The drug vinblastine disrupts microtubule polymerization. How would adding vinblastine to a cell affect the constitutive secretory pathway? Choose one: A. Transport vesicles will not be brought to either the Golgi apparatus or the plasma membrane. B. Transport vesicles will only be brought to the plasma membrane, not to the Golgi apparatus. C. Transport vesicles will only be brought to the Golgi apparatus, not to the plasma membrane. D. Vinblastine will not affect the pathway because microtubules are not involved in secretion.

A. Transport vesicles will not be brought to either the Golgi

Which of these strategies do prokaryotic cells use to isolate and organize their chemical reactions? Choose one: A. aggregating proteins into multicomponent complexes that form biochemical subcompartments with distinct functions B. confining proteins required for different metabolic processes within different membrane-enclosed compartments C. confining the proteins required for different metabolic processes within the plasma membrane D. None; these strategies are used only by eukaryotic cells. E. None; prokaryotes do not regulate their metabolic processes.

A. aggregating proteins into multicomponent complexes that form biochemical subcompartments with distinct functions

Most mitochondrial and chloroplast proteins are made within which part of the cell? Choose one: A. cytosol B. mitochondrion or chloroplast itself C. peroxisome D. endoplasmic reticulum E. Golgi apparatus

A. cytosol

During a pulse-chase experiment with secreted proteins, the proteins are synthesized for a short "pulse" time with radioactive or fluorescent amino acids to label the proteins. During the "chase" period, unlabeled amino acids are added, so any additional proteins synthesized are not labeled. The labeled proteins can then be monitored over time. You complete a pulse-chase experiment to monitor the secretion of a protein from the cell. Which of the following correctly lists the order of locations of the protein during the chase period? Choose one: A. endoplasmic reticulum → transport vesicle → Golgi → transport vesicle → secreted B. nucleus → endoplasmic reticulum → cytosol → Golgi → transport vesicle → secreted C. endoplasmic reticulum → transport vesicle → Golgi → cytosol → secreted D. Golgi → transport vesicle → endoplasmic reticulum → transport vesicle → secreted

A. endoplasmic reticulum → transport vesicle → Golgi → transport vesicle → secreted

Which of the following is true of lysosomes? Choose one: A. Lysosomes contain around 40 types of hydrolytic enzymes, which are optimally active at pH 7.2. B. An ATP-driven H+ pump in the lysosomal membrane maintains the organelle's pH. C. The products of digestion in lysosomes leave the lysosome by transport vesicles. D. Lysosomes have a pH that is higher than that of the cytosol. E. Most of the lysosomal membrane proteins have glycosylated regions on the cytosolic side of the membrane.

B. An ATP-driven H+ pump in the lysosomal membrane maintains the organelle's pH.

What is the function of receptor in receptor-mediated endocytosis? A. Molecules packaged into vesicle for transport B. Captures the correct cargo molecules C. Mediates contact between the receptor and another component D. Shapes the forming vesicle

B. Captures the correct cargo molecules

Proteins destined for the Golgi apparatus, endosomes, lysosomes, and even the cell surface must pass through which organelle? Choose one: A. nucleus B. ER C. peroxisome D. mitochondrion

B. ER

How do the interiors of the ER, Golgi apparatus, endosomes, and lysosomes communicate with each other? Choose one: A. They do not communicate with one another. B. by small vesicles that bud off of one organelle and fuse with another C. by fusing with one another D. by excreting hormones and other small signaling molecules E. by open pores that allow ions to exit and enter the organelles

B. by small vesicles that bud off of one organelle and fuse with another

What is the function of adaptin in receptor-mediated endocytosis? A. Molecules packaged into vesicle for transport B. Captures the correct cargo molecules C. Mediates contact between the receptor and another component D. Shapes the forming vesicle

C. Mediates contact between the receptor and another component

What is true of protein glycosylation in the ER? Choose one: A. A block of sugar residues is added to the N-terminal signal sequence, creating a common, N-linked oligosaccharide. B. Only proteins bearing a dolichol residue become glycosylated. C. Oligosaccharides are added by an enzyme that has its active site on the lumenal side of the ER membrane. D. Sugar residues are added one at a time by a series of enzymes attached to the ER membrane. E. Only proteins phosphorylated on an asparagine residue become glycosylated.

C. Oligosaccharides are added by an enzyme that has its active site on the lumenal side of the ER membrane.

Scientists have modified a clathrin molecule so that it still assembles but forms an open-ended lattice instead of a closed spherical cage. How would this clathrin molecule affect endocytosis in cells? Choose one: A. Vesicles would be larger, increasing the cargo endocytosed. B. All movement of molecules into and out of the cell would cease. C. Vesicles cannot form properly without a clathrin cage, thus inhibiting endocytosis. D. Endocytosis would be unaffected, since adaptors and receptors can still interact.

C. Vesicles cannot form properly without a clathrin cage, thus inhibiting endocytosis.

The movement of materials from the plasma membrane, through endosomes, and then to lysosomes describes which type of pathway? Choose one: A. endolytic pathway B. secretory pathway C. endocytic pathway D. endosomal pathway E. exocytic pathway

C. endocytic pathway

The outer membrane of the nucleus is continuous with the membrane of which other organelle? Choose one: A. endosome B. peroxisome C. endoplasmic reticulum D. Golgi apparatus E. mitochondrion

C. endoplasmic reticulum

Which cellular compartment acts as the main sorting station for extracellular cargo molecules taken up by endocytosis? Choose one: A. clathrin-coated vesicles B. lysosomes C. endosomes D. Golgi apparatus E. transport vesicles

C. endosomes

Through which of the following do proteins travel from one cisterna to the next in the Golgi apparatus? Choose one: A. pores in the cisternal membranes B. bridges that link the cisternae C. transport vesicles that bud from one cisterna and fuse with the next D. transporters in the cisternal membranes E. membranes via osmosis

C. transport vesicles that bud from one cisterna and fuse with the next

How are newly made lipids supplied to the plasma membrane? Choose one: A. via secretory vesicles produced by the regulated exocytosis pathway B. via enzymes that synthesize phospholipids, which are attached to the plasma membrane C. via the constitutive pathway of exocytosis D. via lysosomes E. via vesicles that bud from the ER and fuse with the plasma membrane

C. via the constitutive pathway of exocytosis

What is the function of clathrin in receptor-mediated endocytosis? A. Molecules packaged into vesicle for transport B. Captures the correct cargo molecules C. Mediates contact between the receptor and another component D. Shapes the forming vesicle

D. Shapes the forming vesicle

What happens to proteins with no signal sequence that are made in the cytosol? Choose one: A. They are degraded by proteases. B. They are secreted. C. They are returned to their organelle of origin. D. They remain in the cytosol. E. They are taken up by lysosomes.

D. They remain in the cytosol.

Phagocytosis is a process by which cells do which of the following?Choose one: A. digest their own worn-out organelles B. engage in receptor-mediated endocytosis C. secrete hormones and neurotransmitters D. ingest extracellular fluid and macromolecules E. consume large particles, such as microbes and cell debris

E. consume large particles, such as microbes and cell debris

Which proteins bind to nuclear localization signals on newly synthesized proteins? Choose one: A. nuclear export receptors B. nuclear pore proteins C. signal-recognition particles (SRPs) D. cytosolic fibrils E. nuclear import receptors

E. nuclear import receptors