Endoplasmic Reticulum: Structure, Function, and Role in Protein Synthesis

Question 1

What is a primary function of the endoplasmic reticulum?

Accepted Answer

Folds and modifies proteins

Answer

Synthesizes carbohydrates exclusively

Answer

Synthesizes all lipids in the cell

Answer

Detoxifies substances only

Question 2

What are the primary functions of the rough and smooth endoplasmic reticulum?

Accepted Answer

Rough ER: Protein synthesis; Smooth ER: Lipid synthesis

Answer

Rough ER: Lipid synthesis; Smooth ER: Protein synthesis

Answer

Both rough and smooth ER: Protein synthesis

Answer

Neither rough nor smooth ER: Protein synthesis

Question 3

Which of the following is NOT a function of the endoplasmic reticulum in protein synthesis and modification?

Accepted Answer

Lipid synthesis

Answer

Protein glycosylation

Answer

Protein folding

Answer

Disulfide bond formation

Question 4

Which of the following is NOT a function of the endoplasmic reticulum (ER)?

Accepted Answer

Regulation of cell division

Answer

Synthesis of proteins

Answer

Synthesis of carbohydrates

Answer

Synthesis of lipids

Question 5

The ____ ER is responsible for protein folding and modification.

Accepted Answer

Rough

Answer

Smooth

Answer

Transitional

Answer

Nuclear

Question 6

Which enzyme is involved in the attachment of carbohydrates to proteins in the ER?

Accepted Answer

Oligosaccharyltransferase

Answer

RNA polymerase

Answer

DNA polymerase

Answer

Peptidyl transferase

Question 7

The ER communicates with other organelles via specialized structures called ____.

Accepted Answer

Transport vesicles

Answer

Ribosomes

Answer

Golgi apparatus

Answer

Mitochondria

Question 8

The ____ pathway is a quality control mechanism that monitors protein folding in the ER.

Accepted Answer

Proteasomal

Answer

Lysosomal

Answer

Autophagy

Answer

Ubiquitination

Question 9

The ____ is a structure found in the nuclear envelope that is continuous with the ER.

Accepted Answer

Nuclear pore complex

Answer

Nucleolus

Answer

Chromatin

Answer

Ribosome

Question 10

Which of the following proteins is NOT transported through the endoplasmic reticulum?

Accepted Answer

Hemoglobin

Answer

Insulin

Answer

Collagen

Answer

Albumin

Question 11

Which of the following organelles is directly involved in the transport of proteins from the endoplasmic reticulum?

Accepted Answer

Golgi apparatus

Answer

Mitochondria

Answer

Lysosomes

Answer

Peroxisomes

Question 12

The accumulation of unfolded proteins in the endoplasmic reticulum can trigger a cellular response known as:

Accepted Answer

Unfolded protein response

Answer

Apoptosis

Answer

Autophagy

Answer

Necrosis

Question 13

Which of the following diseases is associated with mutations in proteins that are folded in the endoplasmic reticulum?

Accepted Answer

Cystic fibrosis

Answer

Alzheimer's disease

Answer

Parkinson's disease

Answer

Diabetes mellitus

Question 14

The endoplasmic reticulum is continuous with which of the following nuclear structures?

Accepted Answer

Nuclear envelope

Answer

Nucleolus

Answer

Chromosomes

Answer

Mitochondria

Question 15

The endoplasmic reticulum is divided into two main regions based on the presence of ribosomes. What are these two regions called?

Accepted Answer

Rough and smooth

Answer

Upper and lower

Answer

Proximal and distal

Answer

Central and peripheral

Question 16

In the secretory pathway, how do the endoplasmic reticulum (ER) and Golgi apparatus interact?

Accepted Answer

The ER synthesizes, modifies, and packages proteins for transport to the Golgi apparatus.

Answer

The Golgi apparatus synthesizes proteins and sends them to the ER for modification and packaging.

Answer

The ER and Golgi apparatus work independently in the secretory pathway.

Answer

The Golgi apparatus modifies proteins and sends them back to the ER for packaging.

Question 17

Which type of endoplasmic reticulum is studded with ribosomes?

Accepted Answer

Rough endoplasmic reticulum

Answer

Smooth endoplasmic reticulum

Question 18

Which of the following molecules is **not** processed by the endoplasmic reticulum during protein synthesis?

Accepted Answer

Phospholipids

Answer

Polypeptide chains

Answer

Glycoproteins

Answer

Steroids

Question 19

What is the role of the signal recognition particle (SRP) in protein translocation?

Accepted Answer

It binds to the ribosome and the endoplasmic reticulum membrane to initiate protein translocation.

Answer

It modifies the polypeptide chain to facilitate its entry into the endoplasmic reticulum.

Question 20

Which of the following is a common disease associated with a malfunctioning endoplasmic reticulum?

Accepted Answer

Cystic fibrosis

Answer

Alzheimer's disease

Question 21

What is the relationship between the endoplasmic reticulum and the Golgi apparatus?

Accepted Answer

The Golgi apparatus receives newly synthesized proteins from the endoplasmic reticulum for further processing.

Answer

The endoplasmic reticulum receives modified proteins from the Golgi apparatus for export from the cell.

Question 22

Which of the following is **not** an enzyme responsible for the folding of newly synthesized proteins in the endoplasmic reticulum?

Accepted Answer

Mitochondrial import signal

Answer

Hsp70

Answer

Hsp90

Answer

Calnexin

Question 23

What is the fate of misfolded proteins in the endoplasmic reticulum?

Accepted Answer

They are degraded by proteasomes.

Answer

They are recycled back into the endoplasmic reticulum for proper folding.

Question 24

Which of the following is the primary function of the rough endoplasmic reticulum (RER)?

Accepted Answer

Synthesizes and folds proteins

Answer

Synthesizes complex carbohydrates

Answer

Metabolizes and detoxifies drugs and toxins

Answer

Stores and releases calcium ions

Question 25

Which of the following is NOT a primary function of the endoplasmic reticulum?

Accepted Answer

Carbohydrate metabolism

Answer

Protein synthesis

Answer

Protein folding and modification

Answer

Lipid synthesis

Question 26

Which of the following processes is NOT a primary function of the endoplasmic reticulum?

Accepted Answer

Carbohydrate storage

Answer

Vesicle transport

Answer

Protein synthesis

Answer

Protein modification

Question 27

Which type of endoplasmic reticulum is responsible for synthesizing lipids?

Accepted Answer

Smooth endoplasmic reticulum

Answer

Mitochondrial endoplasmic reticulum

Answer

Nuclear endoplasmic reticulum

Answer

Rough endoplasmic reticulum

Question 28

What is a defining characteristic of the rough endoplasmic reticulum?

Accepted Answer

Attached ribosomes on its surface

Answer

Calcium ion storage

Answer

Lipid synthesis

Answer

Transportation of vesicles

Question 29

Which component plays a key role in directing ribosomes to the endoplasmic reticulum during protein synthesis?

Accepted Answer

Signal recognition particle (SRP)

Answer

Initiation factor

Answer

Golgi body

Answer

Termination codon

Question 30

Which enzyme is primarily involved in the folding of proteins within the endoplasmic reticulum?

Accepted Answer

Protein disulfide isomerase

Answer

RNA polymerase

Answer

Glycosyltransferase

Answer

Peptidyl transferase

Question 31

What is the main function of the endoplasmic reticulum-associated degradation (ERAD) pathway?

Accepted Answer

Elimination of misfolded proteins

Answer

Vesicle transport to the Golgi apparatus

Answer

Protein synthesis

Answer

Protein modification for secretion

Question 32

Which hormone is responsible for stimulating the release of calcium ions from the endoplasmic reticulum?

Accepted Answer

Inositol 1,4,5-trisphosphate (IP3)

Answer

Glucagon

Answer

Estrogen

Answer

Insulin

Question 33

What is the primary function of the KDEL receptor in the endoplasmic reticulum?

Accepted Answer

Retrieval of proteins from the Golgi apparatus

Answer

Degradation of misfolded proteins

Answer

Protein synthesis

Question 34

Which of the following diseases is associated with defects in the endoplasmic reticulum?

Accepted Answer

Cystic fibrosis

Answer

Alzheimer's disease

Answer

Parkinson's disease

Answer

Huntington's disease

Question 35

Which of the following is NOT a function of the endoplasmic reticulum?

Accepted Answer

Hormone synthesis

Answer

Detoxification

Answer

Protein synthesis and folding

Question 36

Which type of endoplasmic reticulum is responsible for ribosomal attachment and protein synthesis?

Accepted Answer

Rough endoplasmic reticulum

Answer

Transitional endoplasmic reticulum

Answer

Smooth endoplasmic reticulum

Question 37

Which of the following processes does NOT occur in the endoplasmic reticulum?

Accepted Answer

Glycolysis

Answer

Detoxification

Answer

Lipid glycosylation

Answer

Protein folding

Question 38

What is the role of the transitional endoplasmic reticulum?

Accepted Answer

Site for protein folding, sorting, and quality control

Answer

Detoxification

Answer

Lipid synthesis

Answer

Protein synthesis

Question 39

What is the primary function of the endoplasmic reticulum chaperone proteins?

Accepted Answer

Assist in protein folding and prevent aggregation

Answer

Degrade misfolded proteins

Answer

Synthesize new proteins

Answer

Transport proteins to their target organelles

Question 40

The primary role of the endoplasmic reticulum (ER) in protein synthesis is to:

Accepted Answer

Provide a site for ribosome attachment and facilitate protein folding and modification.

Answer

Directly synthesize proteins from amino acids.

Answer

Break down proteins.

Question 41

The primary structural difference between rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) is that:

Accepted Answer

RER is studded with ribosomes, while SER lacks them.

Answer

RER is involved in lipid synthesis, while SER handles protein synthesis.

Answer

RER is responsible for detoxification, while SER is involved in protein folding.

Question 42

A patient presents with a genetic defect that affects the function of chaperone proteins within the ER. Which of the following processes is most likely to be impaired?

Accepted Answer

Proper protein folding and assembly.

Answer

DNA replication.

Answer

Cellular respiration.

Answer

Lipid synthesis.

Question 43

Which of the following is NOT a function of the SER?

Accepted Answer

Protein synthesis.

Answer

Lipid synthesis.

Answer

Calcium storage.

Answer

Detoxification.

Question 44

After translocation into the ER lumen, a newly synthesized protein destined for secretion undergoes:

Accepted Answer

Folding and modification within the ER.

Answer

Direct export out of the cell.

Answer

Transport to the Golgi apparatus via microtubules.

Question 45

In studying steroid hormone synthesis, which type of ER would a researcher primarily focus on?

Accepted Answer

SER.

Answer

The Golgi apparatus.

Answer

RER.

Answer

Both RER and SER.

Question 46

The ER signal sequence in protein synthesis serves to:

Accepted Answer

Target the ribosome to the ER membrane.

Answer

Initiate protein folding within the ER lumen.

Answer

Trigger the release of the protein from the ribosome.

Answer

Determine the final destination of the protein after synthesis.

Question 47

A patient with impaired ER protein transport to the Golgi apparatus may primarily experience difficulty with:

Accepted Answer

Secretion of proteins from the cell.

Answer

Lipid synthesis.

Answer

DNA replication.

Answer

Cellular respiration.

Question 48

The ER membrane's ability to support a wide range of functions is facilitated by its:

Accepted Answer

High content of phospholipids and proteins.

Answer

Rigid structure.

Answer

Lack of transmembrane proteins.

Answer

Separation from the nuclear envelope.

Question 49

Which of the following proteins is most likely synthesized by ribosomes attached to the rough endoplasmic reticulum (RER)?

Accepted Answer

Insulin, a hormone secreted by pancreatic cells.

Answer

Hexokinase, an enzyme involved in glycolysis in the cytoplasm.

Answer

Tubulin, a protein that forms microtubules in the cytoskeleton.

Answer

Histones, proteins associated with DNA in the nucleus.

Question 50

A mutation disrupts the function of signal recognition particles (SRPs) in a cell. What is the most likely consequence of this mutation?

Accepted Answer

Proteins destined for the ER lumen will accumulate in the cytoplasm.

Answer

The ER will be unable to synthesize lipids.

Answer

Proteins will be misfolded within the ER lumen.

Answer

Protein synthesis will cease entirely.

Question 51

What is a primary function of the smooth endoplasmic reticulum (SER)?

Accepted Answer

Lipid and steroid hormone synthesis.

Answer

Modification and packaging of secreted proteins.

Answer

Degradation of misfolded proteins.

Answer

Synthesis of ribosomes.

Question 52

What is the role of chaperone proteins in the endoplasmic reticulum?

Accepted Answer

Assist in the proper folding of newly synthesized proteins.

Answer

Synthesize lipids in the SER.

Answer

Degrade misfolded proteins through the ubiquitin-proteasome pathway.

Answer

Transport proteins from the ER to the Golgi apparatus.

Question 53

Which cellular process is directly linked to the unfolded protein response (UPR)?

Accepted Answer

Increased production of chaperone proteins.

Answer

Increased lipid synthesis.

Answer

Enhanced protein glycosylation.

Answer

Breakdown of the endoplasmic reticulum.

Question 54

After exiting the endoplasmic reticulum, proteins that undergo modification in the Golgi apparatus are primarily destined for which of the following locations?

Accepted Answer

Lysosomes, plasma membrane, or secretion outside the cell.

Answer

Peroxisomes.

Answer

Mitochondria.

Answer

Nucleus.

Question 55

Sarcoplasmic reticulum, found in muscle cells, is a specialized type of endoplasmic reticulum. What is its primary function?

Accepted Answer

Storage and release of calcium ions for muscle contraction.

Answer

Degradation of old or damaged muscle proteins.

Answer

Synthesis of ATP for muscle energy.

Answer

Production of muscle-specific proteins.

Question 56

Certain drugs, like phenobarbital, can lead to increased tolerance. How is this phenomenon related to the endoplasmic reticulum?

Accepted Answer

Phenobarbital induces the synthesis of drug-metabolizing enzymes in the smooth ER.

Answer

Phenobarbital inhibits calcium storage in the sarcoplasmic reticulum, reducing drug response.

Answer

Phenobarbital disrupts protein folding in the rough ER, leading to decreased drug efficacy.

Answer

Phenobarbital directly binds to receptors in the ER, leading to reduced drug sensitivity.

Question 57

Which of the following diseases is associated with defects in protein folding within the endoplasmic reticulum?

Accepted Answer

Cystic fibrosis.

Answer

Down syndrome.

Answer

Sickle cell anemia.

Answer

Huntington's disease.