Question

1. Which type of cells below is not known for its extensively developed SER?

A. skin cells

B. kidney tubule cells

C. skeletal muscle cells

D. steroid-producing endocrine cells

E. both skeletal muscle cells and kidney tubule cells

2. What determines the function of a cell's smooth endoplasmic reticulum?

A. its lipid content

B. its polynucleotide content

C. its carbohydrate content

D. its protein content

E. its age

3. What is responsible for recognizing lysosomal enzymes and localizing them to the lysosomes?

1) mannose 6-phosphate receptors

2) MPRs

3) integral membrane proteins that span the TGN membranes

4) intra Golgi receptors that reside in the TGN lumen

A. 1

B. 1, 2, and 4

C. 3

D. 4

E. 1, 2, and 3

4. Name two proteins you would expect to find as integral components of the rough ER membrane that would be absent from the smooth ER?

5. Name two proteins of the smooth ER that would not be present in the rough ER?

6. Which of the following cells would you expect to be engaged most heavily in bulk-phase endocytosis: an erythrocyte, a pancreatic acinar cell, a skeletal muscle cell? Why?

7. Would you expect the properties of the luminal side of Golgi membranes to be more similar to the extracellular or cytosolic side of the plasma membrane? Why?

8. If you were to add a drug that interfered with the ability of ribosomes to bind to mRNA, what effect would this be expected to have on the structure of the rough ER?

Answer 1

Answer 1:

Option ‘A’ is correct

SER involves in synthesis of glucose during gluconeogenesis, lipids and steroid hormones, detoxification and storage of calcium ions.

Answer 2:

Option ‘D’ is correct

Enzymes (Protein) that are located in the membrane determines the function of cell's SER.

Answer 3:

Option ‘E’ is correct

Localizing of lysosomal enzymes to lysosomes is carried out by the P-type lectins, mannose 6-phosphate receptor (MPRs) and all this is dependent upon recognition of Man-6-P residues by trans-Golgi network (TGN).

Answer 4:

The two proteins that are expect to find as integral components of the rough ER membrane and would be absent from the smooth ER are:

• SRP receptor (Sequence Recognition Particle receptor)
• Sec61 proteins (translocation channel)