Chapter 11 Questions and Answers

Which of the following is NOT a component of the endomembrane system?

mitochondrion

Which of the following solutions is most chemically similar to the cytosolic solution?

nucleoplasm

All proteins first enter the endomembrane system through the:

ER

Proteins that are trafficked through the endomembrane system move from the ER to the ___ before continuing on to other endomembrane organelles.

the Golgi

In the “Golgi Airlines” analogy, which compartment is analogous to an airport gate?

Golgi

Which of the following is the correct order in which proteins are trafficked through the endomembrane system?

ER, Golgi, lysosome

Which of the following consists of many interconnected flattened sacs called cisternae?

rough ER

The rough ER and the smooth ER are continuous of each other.

True

The process of translating proteins directly into the rough ER is called:

co-translational translocation.

What happens when SRP binds to a ribosome?

translation pauses

Binding of SRP to the SRP receptor results in hydrolysis of (choose the best answer):

both the SRP-bound and SRP receptor-bound GTP.

Which of the following structures are lined up during co-translational translocation?

the exit tunnel of the ribosome and the central channel of the translocon

Stop signals are:

rich in hydrophobic residues.

Cell membrane proteins are first translated into the rough ER lumen and then transferred to the membrane later in the endomembrane system.

False

Disulfide bonds are formed between two ___ amino acids.

cysteine

Disulfide bonds provide a level of protection to proteins from highly oxidative environments.

True

Where would we expect to find glycosylated proteins?

rough ER

The glycocalyx acts as a physical buffer that shields and protects the rough ER membrane from enzymes and other chemicals that could cause damage.

False

What is the function of oligosaccharyl transferase?

to transfer an oligosaccharide from a dolichol to a protein

What does “N” stand for in N-linked glycosylation?

nitrogen

BiP and calnexin, bind to misfolded or partially folded soluble proteins via ___ to retain them in the rough ER.

hydrophobic interactions

Only proteins that meet quality control standards will be packaged into vesicles for departure from ER exit sites.

True

The UPR is triggered by:

the dimerization of Ire1

If UPR fails, what does the cell try next?

dislocation

Transmembrane proteins in the endomembrane system are exposed only to the non-cytosolic side of their compartment; however, soluble proteins in the endomembrane system are exposed to both non-cytosolic and cytosolic sides.

False

Both transmembrane proteins and the lipids within which they’re embedded display asymmetry with respect to cytosolic versus non-cytosolic-facing sides.

True