Chapter 12 : The Endomembrane System and Protein Sorting

In which of the following organelles would you expect to first find a protein destined to be secreted from a cell?

Endoplasmic reticulum.

The endoplasmic reticulum is a site for

N-linked glycosylation of polypeptides.

Comparing cells synthesizing proteins and cells secreting steroid hormones, the cells synthesizing the steroid hormones have

More smooth ER.

Which of the following molecules forms the coat during receptor-mediated endocytosis-coated pit formation?

Clathrin.

The continuous release of mucus by the epithelial cells lining the respiratory tract is an example of

Constitutive secretion.

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

Has a membrane-spanning domain length equals the thickness of the cis-Golgi membrane.

The vesicles that are anchored to the plasma membrane at a nerve cell presynaptic site are specialized for

Polarized secretion.

Which of the following statements is false regarding phagocytosis?

It is mediated by clathrin at the plasma membrane. (It can ingest large particles, It involves the projection of pseudopods, and It is used by amoebae to ingest food are all correct).

In receptor-mediated endocytosis, each of the following is a fate for the receptors and/ or vesicle contents except

Release from the vesicle into the nucleus. (Transcytosis, Digestion in a lysosome, and recycling to the plasma membrane are all correct).

Each of the following is a lysosomal storage disease caused by deficiency in lysosomal enzymes except

Familial hypercholesterolemia. (Hurler syndrome, Hunter syndrome, Type ll glycogenesis, and Tay-Sachs disease are all correct).

Each of the following is part of the core oligosaccharide side chain in the ER except

Erythrose. (Mannose, Glucose, and All are part of the core oligosaccharide are correct).

Peroxisomes

Are not derived from the endoplasmic reticulum.

Which of the following organelles has the ability to catabolize alkanes found in oil and petroleum products?

Peroxisomes.

A protein that is N-glycosylated is expected to be

Secreted from the cell.

Each of the following is an endoplasmic reticulum function except

All are endoplasmic reticulum functions. (Peptide folding, The assembly of multimeric proteins, and The export of protein cannot be folded into the cytoplasm for destruction are all correct).

Total internal reflection (TIRF) microscopy is best to visualize fluorescently labeled protein activity

On the lower surface of a cell.

Which of the following is associated with extracellular digestion caused by the release of the lysosomes enzymes into the environment?

Rheumatoid arthritis.

Each of the following organelles is part of the endomembrane system except

The peroxisome. (The Golgi complex, The smooth endoplasmic reticulum, The endosome, and The rough endoplasmic reticulum are all correct).

Each of the following is true about botulinum toxin (Botox) except

Botox is a SNARE protein. (The toxin is one of the most potent toxins known, It can be used therapeutically to stop muscle spasms, It has been used to remove wrinkles caused by muscle contractions, and It has potential to use as a migraine headache treatment are all correct).

You have isolated two fractions containing similar-sized vesicles by configuration. 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?

Catalase.

On which of the following intercellular locations does clathrin organize and coat and form vesicles?

Trans-Golgi complex.

Each of the following is a component involved in SNARE hypothesis model mechanism except

All are involved. (v-SNARE, Rab GTPase, Tethering complex, and NSF protein are all correct).

In a lysosomal storage disease, newly synthesized lysosome hydrolyses are secreted from the cells rather than being delivered to the lysosomes. What is one possible mechanism for this result?

All the hydrolase genes are mutated, resulting in synthesis by ribosomes free in the cytoplasm rather than on the endoplasmic reticulum membrane.

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

Regulated secretion.

Which of the following techniques would be best used to measure the strength of a v-SNARE-t-SNARE interaction?

Optical tweezers.

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?

Add a KDEL sequence near its C-terminus.

Which of the following proteins requires GTP in the process of LDL receptor-mediated endocytosis?

Dynamin.

Each of the following is part of the endomembrane system, except

Peroxisomes. (Endosomes, Golgi complex, lysosomes, and zymogen granules are all correct).

Sorting of hormones into regulated secretory vesicles in the trans-Golgi network involves

Formation of large aggregates.

In animal cells, oxidation of very long fatty acids occurs in

Peroxisomes.

Which of the following cell types would be associated with the greatest concentration of low-density lipoproteins (LDLs)?

Liver.

Uptake of low-density lipoproteins (LDLs) occurs by

Receptor-mediated endocytosis.

The low PH of lysosomes is established by

ATP-dependent proton pumps.

The plant cell organelle most analogous to animal cell lysosomes is the

Vacuole.

The plant cell organelle most analogous to the animal cell endosome is the

Provacuole.

A COPII-coated vesicle has all the following except

AP-2. (Sec 13/31, Sec 23/34, v-SNARE and Sar1 are all correct).

Which of the following cellar processes may be inhibited in tumor cells?

Autophagy.