Life Sciences Multiple Choice Questions on “Endoplasmic Reticulum”.
1. Which of the following is the largest single membrane-bound intracellular compartment?
A. Ribosome
B. Golgi apparatus
C. Nucleus
D. Endoplasmic reticulum
Answer: D
Clarification: Endoplasmic reticulum is a network of closed and flattened single membrane-bound intracellular structure. ER lumen is the enclosed compartment between ER membranes which are physiologically active.
2. Protein undergoes modifications in ER before reaching their final destination.
A. True
B. False
Answer: A
Clarification: After the synthesis of protein, it undergoes various modifications before reaching their final destination i.e. Glycosylation, protein folding, the formation of disulfide bridges, and specific proteolytic cleavage.
3. What is microsome?
A. Compartment of Golgi
B. Smaller ribosomes
C. Small ER compartments
D. Small vesicles of fragmented ER
Answer: D
Clarification: Microsomes are small vesicles formed by the breakdown of ER membrane into fragments. Microsomes which are derived from RER are known as rough microsomes while microsomes lacking ribosomes are called smooth microsome.
4. Endoplasmic reticulum membrane which is associated with ribosomes is called_______
A. ER lumen
B. Smooth endoplasmic reticulum
C. Rough endoplasmic reticulum
D. Endosome
Answer: C
Clarification: Endoplasmic reticulum membrane has been divided into rough or smooth based on the association of ribosome with their cytoplasmic surface. The region of ER that is bounded with ribosomes is called rough endoplasmic reticulum or RER.
5. Name the antibiotic which inhibits the synthesis of oligosaccharides?
A. Tunicamycin
B. Cephalosporins
C. Penicillins
D. Ofloxacin
Answer: A
Clarification: Tunicamycin is an antibiotic which inhibits the synthesis of oligosaccharides by blocking the first step in glycosylation of proteins.
6. Which of the following is not the function of Glycosylation?
A. Helps in proper folding of the protein
B. Confer stability in proteins
C. Helps in cell-cell adhesion
D. Synthesis of membrane lipid
Answer: D
Clarification: Glycosylation is the process of attachment of sugars molecule to the nitrogen atom in an amino acid residue of the protein. synthesis of membrane lipid is incorrect, SER produces membrane lipids.
7. Name the site where detoxification of xenobiotic compounds takes place?
A. Cytosol
B. RER
C. SER
D. Ribosome
Answer: C
Clarification: SER is smooth endoplasmic reticulum which is a part of endoplasmic reticulum membrane where ribosome is not attached. It is the major site for removal of xenobiotics, and the reaction is catalyzed by cytochrome P-450.
8. Name the sequence which allows the resident protein to retain in ER lumen?
A. KDEL
B. KKXX
C. KLDE
D. KXXK
Answer: A
Clarification: KDEL stands for lys-asp-glu-leu sequences, present at the C-terminus of resident proteins. These sequences act as a sorting signal which is necessary for retention of protein in the ER.
9. Which of the following coated vesicle transport protein from ER to Golgi?
A. Clathrin
B. COP II
C. COP I
D. COP III
Answer: B
Clarification: COP II vesicles form for an anterograde pathway from ER to the Golgi. These transport vesicles arise from specialized coated regions of the membrane.
10. Name the coated vesicle which is used to transfer protein from plasma membrane to endosome?
A. Clathrin
B. COP I
C. COP II
D. COP III
Answer: A
Clarification: Clathrin along with different adapter proteins (APs) forms coated vesicles which transport protein from plasma membrane to endosome.
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