Chapter 11 Questions and Answers

Chapter 11 Chapter Questions

Endomembrane System Component

• Question: Which of the following is NOT a component of the endomembrane system?
• Answer: mitochondrion

Cytosolic Solution Similarity

• Question: Which of the following solutions is most chemically similar to the cytosolic solution?
• Answer: nucleoplasm

Protein Entry into Endomembrane System

• Question: All proteins first enter the endomembrane system through the:
• Answer: ER

Protein Trafficking After ER

• Question: Proteins that are trafficked through the endomembrane system move from the ER to the ___ before continuing on to other endomembrane organelles.
• Answer: the Golgi

Golgi Airlines Analogy

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

Protein Trafficking Order

• Question: Which of the following is the correct order in which proteins are trafficked through the endomembrane system?
• Answer: ER, Golgi, lysosome

Cisternae

• Question: Which of the following consists of many interconnected flattened sacs called cisternae?
• Answer: rough ER

Rough ER and Smooth ER Continuity

• Question: The rough ER and the smooth ER are continuous of each other.
• Answer: True

Co-translational Translocation

• Question: The process of translating proteins directly into the rough ER is called:
• Answer: co-translational translocation.

SRP Binding to Ribosome

• Question: What happens when SRP binds to a ribosome?
• Answer: translation pauses

SRP Receptor Binding

• Question: Binding of SRP to the SRP receptor results in hydrolysis of (choose the best answer):
• Answer: both the SRP-bound and SRP receptor-bound GTP.

Structures Aligned During Co-translational Translocation

• Question: Which of the following structures are lined up during co-translational translocation?
• Answer: the exit tunnel of the ribosome and the central channel of the translocon

Stop Signals

• Question: Stop signals are:
• Answer: rich in hydrophobic residues.

Cell Membrane Protein Translation

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

Disulfide Bond Formation

• Question: Disulfide bonds are formed between two ___ amino acids.
• Answer: cysteine

Disulfide Bond Protection

• Question: Disulfide bonds provide a level of protection to proteins from highly oxidative environments.
• Answer: True

Glycosylated Protein Location

• Question: Where would we expect to find glycosylated proteins?
• Answer: rough ER

Glycocalyx Function

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

Oligosaccharyl Transferase Function

• Question: What is the function of oligosaccharyl transferase?
• Answer: to transfer an oligosaccharide from a dolichol to a protein

N-linked Glycosylation

• Question: What does “N” stand for in N-linked glycosylation?
• Answer: nitrogen

BiP and Calnexin Binding

• Question: BiP and calnexin, bind to misfolded or partially folded soluble proteins via ___ to retain them in the rough ER.
• Answer: hydrophobic interactions

Protein Quality Control

• Question: Only proteins that meet quality control standards will be packaged into vesicles for departure from ER exit sites.
• Answer: True

UPR Trigger

• Question: The UPR is triggered by:
• Answer: the dimerization of Ire1

UPR Failure

• Question: If UPR fails, what does the cell try next?
• Answer: dislocation

Transmembrane and Soluble Proteins

• Question: 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.
• Answer: False

Protein and Lipid Asymmetry

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