Protein Synthesis and Secretion Process in Cells

Which organelle is particularly abundant in cells with active lipid metabolism such as adipose cells and hepatocytes?

Mitochondria
Rough endoplasmic reticulum (RER)
Smooth endoplasmic reticulum (SER) (correct)
Golgi apparatus

Which chaperone is located on the inner side of the ER membrane and assists in pulling proteins into the ER lumen?

BiP chaperone (correct)
Hsp90
Hsp70
TRiC chaperone

What is the major function of the smooth endoplasmic reticulum (SER) in eukaryotic cells?

DNA replication
Energy production
Membrane lipid synthesis (correct)
Protein synthesis

Which organelle can the SER establish connections with?

Peroxisomes (C) Signup and view all the answers

In which cells is the smooth endoplasmic reticulum (SER) particularly abundant due to their production of steroid hormones?

Leydig cells in testis (D) Signup and view all the answers

What is a significant function of the SER in the liver?

Detoxification of lipid-soluble substances (B) Signup and view all the answers

What is the role of proteolysis in post-translational processing of proteins?

Specific cleavage of the polypeptide chain (A) Signup and view all the answers

Which organelle is responsible for synthesizing Ceramide, the precursor of Glycosphingolipids and Sphingomyelin?

Endoplasmic reticulum (ER) (C) Signup and view all the answers

What is the function of molecular chaperones in protein folding?

Facilitating the folding of other proteins into their native conformation (B) Signup and view all the answers

Which type of cleavage is necessary for translocating proteins across membranes?

Removal of the signal sequence (D) Signup and view all the answers

In post-translational processing, what happens after folding of proteins?

Glycosylation takes place (B) Signup and view all the answers

Which process is responsible for converting preproinsulin into insulin by removing an internal peptide?

Proteolysis (A) Signup and view all the answers

Which of the following statements about the differences between N-glycosylation and O-glycosylation is correct?

All of the above statements are correct. (D) Signup and view all the answers

Which of the following statements about the importance of glycosylation is not mentioned in the text?

Glycosylation plays a role in the formation of the extracellular matrix. (B) Signup and view all the answers

Which of the following statements about sulfation is correct?

Sulfation involves the addition of sulfate groups (SO₄²⁻) and typically occurs in proteoglycans. (A) Signup and view all the answers

Which of the following statements about phosphorylation is incorrect?

Phosphorylation occurs primarily in the nucleus and cytosol. (B) Signup and view all the answers

Which of the following statements about the transfer of monosaccharides is correct?

Monosaccharides are transferred bound to UDP or CMP. (C) Signup and view all the answers

Based on the information provided in the text, which of the following statements about the sugar chains in O-glycosylation is incorrect?

The sugar chains in O-glycosylation are longer than in N-glycosylation. (A) Signup and view all the answers

Which of the following is responsible for recognizing the signal peptide and initiating the co-translational translocation process?

SRP (Signal Recognition Particle) (B) Signup and view all the answers

What is the function of the SRP Receptor in the co-translational translocation pathway?

It facilitates the binding of the ribosome-SRP complex to the ER membrane (D) Signup and view all the answers

Which of the following is responsible for cleaving the signal peptide from the polypeptide chain during the co-translational translocation process?

Signal Peptidase (D) Signup and view all the answers

What is the function of the translocon channel in the co-translational translocation pathway?

It provides a channel for the polypeptide chain to be translocated into the ER lumen (A) Signup and view all the answers

What is the role of ribophorins in the co-translational translocation pathway?

They stabilize the binding of the ribosome to the ER membrane during translocation (D) Signup and view all the answers

Which of the following statements accurately describes the post-translational translocation pathway?

It involves the translocation of fully synthesized proteins into the ER lumen after their translation on free cytosolic ribosomes (C) Signup and view all the answers

What is the primary source of mature lysosomes (secondary lysosomes)?

Fusion of transport vesicles from the trans Golgi network containing acid hydrolases and endosomes with endocytosed molecules (A) Signup and view all the answers

What is the primary function of vesicles budding from the trans face of the Golgi apparatus?

Transporting proteins to their final destinations, such as the plasma membrane or organelle membranes (D) Signup and view all the answers

Which of the following statements best describes the role of motor proteins and microtubules in vesicular transport?

Motor proteins associated with microtubules facilitate the movement of transport vesicles to their destinations (C) Signup and view all the answers

What is the primary difference between constitutive secretion vesicles and stimulus-regulated secretion vesicles?

Constitutive secretion vesicles contain proteins that are continuously secreted, while stimulus-regulated secretion vesicles contain proteins that are secreted in response to specific stimuli (D) Signup and view all the answers

Which of the following statements accurately describes the sorting and packaging of proteins in the secretory pathway?

Newly synthesized proteins are sent to the cis Golgi on vesicles generated in the transitional endoplasmic reticulum (D) Signup and view all the answers

What is the final destination of transport vesicles containing membrane-anchored proteins?

Organelle membranes or the plasma membrane (C) Signup and view all the answers