chapter 12

Question 1

In which of the following organelles would you expect to first find a protein destined to be
secreted from a cell?
A) Endosome
B) Golgi apparatus
C) Lysosome
D) Secretory vesicle
E) Endoplasmic reticulum

Answer 1

E

Question 2

The endoplasmic reticulum is a site for
A) potassium storage in muscle cells.
B) drug detoxification by catalase.
C) N-linked glycosylation of polypeptides.
D) addition of lipid residues.
E) degradation of foreign material brought into the cell by phagocytosis.

Answer 2

C

Question 3

Comparing cells synthesizing secretory proteins and cells secreting steroid hormones, the cells
synthesizing the steroid hormones have
A) more rough ER.
B) more smooth ER.
C) equal amounts of smooth and rough ER.
D) equal amounts of smooth and rough ER, but more lysosomes.
E) equal amounts of smooth and rough ER, but fewer lysosomes.

Answer 3

B

Question 4

Which of the following molecules forms the coat during receptor-mediated endocytosis-
coated pit formation?
A) Mannose-6-phosphate
B) T-SNARE
C) Clathrin
D) Tethering protein
E) Caveolin

Answer 4

C

Question 5

The continuous release of mucus by the epithelial cells lining the respiratory tract is an
example of
A) regulated secretion.
B) constitutive secretion.
C) the mucus response.
D) clathrin-coated pit formation.
E) phagocytosis.

Answer 5

B

Question 6

When a membrane protein is radioactively labeled during synthesis and followed through the
various organelles in the secretory pathway, all the radioactivity is concentrated in the cis-Golgi
apparatus six hours after the protein synthesis. This suggests that the protein
A) was imported directly into the cis-Golgi posttranslationally.
B) contains a KDEL sequence near its C-terminus.
C) has a membrane-spanning domain length equals the thickness of the cis-Golgi membrane.
D) has a mannose-6-phosphate tag.
E) is misfolded and being degraded in the cis-Golgi

Answer 6

C

Question 7

The vesicles that are anchored to the plasma membrane at a nerve cell presynaptic site are
specialized for
A) constitutive secretion.
B) regulated secretion.
C) polarized secretion.
D) lysosome secretion.
E) endocytosis.

Answer 7

C

Question 8

Which of the following statements is false regarding phagocytosis?
A) It can ingest large particles.
B) It involves the projection of pseudopods.
C) It is used by amoebae to ingest food.
D) It is mediated by clathrin at the plasma membrane.
E) It is used by macrophages and neutrophils to ingest bacteria.

Answer 8

D

Question 9

In receptor-mediated endocytosis, each of the following is a fate for the receptors and/or
vesicle contents except
A) transcytosis.
B) digestion in a lysosome.
C) recycling to the plasma membrane.
D) release from the vesicle into the nucleus.
E) All are possible fates.

Answer 9

D

Question 10

Each of the following is a lysosomal storage disease caused by a deficiency in lysosomal
enzymes except
A) familial hypercholesterolemia.
B) Hurler syndrome.
C) Hunter syndrome.
D) type II glycogenosis.
E) Tay-Sachs disease.

Answer 10

A

Question 11

Each of the following is part of the core oligosaccharide side chain in the ER except
A) N-acetyl glucosamine.
B) erythrose.
C) mannose.
D) glucose.
E) All are part of the core oligosaccharide.

Answer 11

B

Question 12

Peroxisomes
A) are not derived from the endoplasmic reticulum.
B) are bounded by double membranes.
C) possess acid phosphatase activity.
D) possess mannose phosphotransferase activity.
E) exist only in algae and photosynthetic cells in plants.

Answer 12

A

Question 13

Which of the following organelles has the ability to catabolize alkanes found in oil and
petroleum products?
A) Mitochondria
B) Smooth endoplasmic reticulum
C) Peroxisomes
D) Lysosomes
E) Late endosomes

Answer 13

C

Question 14

A protein that is N-glycosylated is expected to be
A) secreted from the cell.
B) retained in the endoplasmic reticulum.
C) localized in the Golgi body.
D) imported into a cell by endocytosis.
E) a peroxisome enzyme.

Answer 14

A

Question 15

Each of the following is an endoplasmic reticulum function except
A) addition of carbohydrate to proteins to make glycoproteins.
B) peptide folding.
C) the assembly of multimeric proteins.
D) the export of protein that cannot be folded into the cytoplasm for destruction.
E) All are endoplasmic reticulum functions.

Answer 15

E

Question 16

Total internal reflection (TIRF) microscopy is best used to visualize fluorescently labeled
protein activity
A) that is too small to see with regular light microscopy.
B) on the upper surface of a cell.
C) in the Golgi.
D) on the lower surface of a cell.
E) in the nucleus.

Answer 16

D

Question 17

Which of the following is associated with extracellular digestion caused by release of the
lysosomes enzymes into the environment?
A) Tay-Sachs disease
B) Rheumatoid arthritis
C) Autophagy
D) Hunter syndrome
E) Hurler syndrome

Answer 17

B

Question 18

Each of the following is true about botulinum toxin (Botox) except
A) The toxin is one of the most potent toxins known.
B) Botox is a SNARE protein.
C) It can be used therapeutically to stop muscle spasms.
D) It has been used to remove wrinkles caused by muscle contractions.
E) It has potential use as a migraine headache treatment.

Answer 18

B

Question 19

You have isolated two fractions containing similar-sized vesicles by centrifugation. You
suspect one fraction contains lysosomes and the other contains peroxisomes. To confirm that a
fraction contains peroxisomes, you would assay for which of the following enzymes?
A) Acid phosphatase
B) β-glucuronidase
C) Ribonuclease
D) A protease
E) Catalase

Answer 19

E

Question 20

On which of the following intracellular locations does clathrin organize a coat and form
vesicles?
A) Lysosomes
B) Trans-Golgi network
C) Endoplasmic network
D) Inner membrane of mitochondria
E) Regulated secretory vesicles

Answer 20

B

Question 21

Each of the following is a component involved in the SNARE hypothesis model mechanism
except
A) v-SNARE.
B) Rab GTPase.
C) tethering complex.
D) NSF protein.
E) All are involved.

Answer 21

E

Question 22

In a lysosomal storage disease, newly synthesized lysosome hydrolases are secreted from the
cells rather than being delivered to the lysosomes. What is one possible mechanism for this
result?
A) The cis-Golgi network lacks a proton gradient.
B) The ER is unable to produce lysosomal vesicles.
C) Lysosomal enzymes are not phosphorylated in the rough ER.
D) Mannose is not phosphorylated in the cis-Golgi network.
E) All the hydrolase genes are mutated, resulting in synthesis by ribosomes free in the cytoplasm
rather than on the endoplasmic reticulum membrane.

Answer 22

D

Question 23

Pancreatic acinar cells produce and store hydrolytic enzymes in zymogen granules until
hormones signal the cell to release the enzymes in a process known as
A) transport secretion.
B) regulated secretion.
C) constitutive secretion.
D) intracellular secretion.
E) consistent secretion.

Answer 23

B

Question 24

Which of the following techniques would be best used to measure the strength of a
v-SNARE-t-SNARE interaction?
A) X-ray crystallography
B) TIRF microscopy
C) GFP fusion proteins
D) Optical tweezers
E) Radioactive pulse labeling

Answer 24

D

Question 25

Using genetic engineering techniques, which of the following would you do to a protein that normally is constitutively secreted to make it accumulate in the ER? A) Fuse it to GFP. B) Add an amino acid that would get a mannose-6-phosphate group added to its carbohydrate. C) Add a KDEL sequence near its C-terminus. D) Mutate one of the asparagines that is normally glycosylated to an alanine, which is not glycosylated. E) None of these would cause the protein to accumulate in the ER.

Answer 25

C

Question 26

Which of the following proteins requires GTP in the process of LDL receptor-mediated endocytosis? A) LDL receptor B) Dynamin C) ap-2 complex D) Uncoating enzyme E) Clathrin

Answer 26

B

Question 27

A protein that is normally localized in the cytoplasm has been engineered so that it will be secreted from the cell instead. Which of the following represents the most likely pathway for the protein after it has been completely synthesized? A) Rough ER → Golgi → secretory vesicle → environment B) Rough ER → Golgi → smooth ER → cytoplasm → environment C) cytoplasm → rough ER → Golgi → secretory vesicle → environment D) Smooth ER → Golgi → secretory vesicle → environment E) Rough ER → secretory vesicle → Golgi → environment

Answer 27

A

Question 28

Sorting of secretory proteins into regulated secretory vesicles in the trans-Golgi network involves A) mannose-6-phosphorylation. B) formation of large aggregates. C) a KDEL receptor. D) a zymogen granule receptor. E) O-linked glycosylation.

Answer 28

B

Question 29

In animal cells, oxidation of very long fatty acids occurs in A) mitochondria. B) peroxisomes. C) lysosomes. D) the smooth endoplasmic reticulum. E) residual bodies.

Answer 29

B

Question 30

Which of the following cell types would be associated with the greatest concentration of low-density lipoproteins (LDLs)? A) Skin B) Muscle C) Connective tissue D) Blood E) Liver

Answer 30

E

Question 31

Uptake of low-density lipoproteins (LDLs) occurs by A) simple diffusion. B) phagocytosis. C) facilitated transport. D) receptor-mediated endocytosis. E) pinocytosis.

Answer 31

D

Question 32

The low pH of lysosomes is established by A) acid hydrolases. B) ATP-dependent proton pumps. C) β-glucuronidases. D) catalases. E) superoxide dismutases.

Answer 32

B

Question 33

The plant cell organelle most analogous to animal cell lysosomes is the plant A) vacuole. B) glyoxysome. C) microsome. D) endosome. E) leaf peroxisome.

Answer 33

A

Question 34

The plant cell organelle most analogous to the animal cell endosome is the A) provacuole. B) lysosome. C) peroxisome. D) glyoxysome. E) None of the above are analogous.

Answer 34

A

Question 35

A COPII-coated vesicle has all of the following except A) Sec 13/31. B) Sec 23/34. C) v-SNARE. D) Sar1. E) AP-2.

Answer 35

E

Question 36

Which of the following cellular processes may be inhibited in tumor cells? A) Autophagy B) N-linked glycosylation C) Caveolae uptake D) LDL degradation E) Catalase activity

Answer 36

A

Question 37

Using the techniques of genetic engineering, you design a protein you want to accumulate within the ER of yeast cells. To accomplish this goal, you need to A) do nothing; all proteins go through the ER. B) incorporate appropriate mannose-6-phosphate groups. C) incorporate the appropriate DNA sequence(s) to create signal sequences in the mature peptide. D) incorporate radioactive amino acids into the protein. E) remove the N-formyl group located at the N-terminus of the polypeptide.

Answer 37

C

Question 38

How do proteins become embedded in the membrane of the endoplasmic reticulum? A) By protein chaperones that insert polypeptides into the ER membrane B) By splicing of proteins on either side of the ER membrane C) Via stop- and start-transfer sequences that stop and start translocation of a polypeptide through the ER membrane, resulting in transmembrane proteins D) By post-translational import can results in a transmembrane ER protein E) Via transit sequences that target polypeptides made in the cytosol for the ER membrane.

Answer 38

C

Question 39

Ribosomes that do not anchor on the surface of the rough endoplasmic reticulum during translation most probably A) are synthesizing cytoplasmic proteins. B) have a defect in ribosomal proteins that allow attachment to the surface. C) have a signal peptidase error. D) do not make the appropriate anchor protein. E) All of the above are probable reasons.

Answer 39

A

Question 40

Which of the following organelles does not receive proteins by posttranslational import of proteins synthesized on cytoplasmic ribosomes? A) Lysosome B) Nucleus C) Mitochondria D) Peroxisomes E) Chloroplast

Answer 40

A

Question 41

The unfolded protein response slows the production of ________ and increases the ________. A) signal recognition particles; activity of proteasomes B) most proteins; production of lysosomal proteins C) protein disulfide isomerase; activity of proteasomes D) most proteins; production of proteins required for protein folding and degradation

Answer 41

D

Question 42

Cytosolic polypeptides are transported to a target organelle via A) transportin mechanisms. B) post-translational import. C) cotranslational import. D) the importin protein. E) the activity of ribosomes.

Answer 42

B

Question 43

The transfer of polypeptides into the ER is called A) transit sequence import. B) post-translational import. C) cotranslational import. D) endoplasmic import. E) ribosomal import.

Answer 43

C