Question

For each of the following statements, indicate if it is true of the rough ER only, of the smooth ER only, of both rough and smooth ER, or of neither. Sort each statement into the appropriate bin. ResetHelp Is involved in the breakdown of glycogenIs the site for biosynthesis of secretory proteins.Contains less cholesterol than does the plasma membrane.Has ribosomes attached to its outer (cytosolic) surface.Usually consists of flattened sacs.Tends to form tubular structures.Is involved in the detoxification of drugs.Is the site for the folding of membrane-bound proteins.Visible only by electron microscopy.

Answer 1

Answer:

• Is involved in the breakdown of glycogen --> smooth ER
• Is the site for biosynthesis of secretory proteins --> rough ER
• Contains less cholesterol than does the plasma membrane --> Neither.
• Has ribosomes attached to its outer (cytosolic) surface --> rough ER
• Usually consists of flattened sacs --> rough ER
• Tends to form tubular structures --> Both. Rough ER + Smooth ER

• Is involved in the detoxification of drugs --> smooth ER
• Is the site for the folding of membrane-bound proteins --> rough ER
• Visible only by electron microscopy --> Both. Rough ER + Smooth ER

Explanation:

Rough ER:

• Its membranes form flattened piled sacs and elongated tubules, with many ribosomes attached.  
• The main function of the RER is to synthesize proteins that are destined to different target places in the cell. It is also in charge of the proteins folding and maturation.

Smooth ER:  

• Membrane interconnected tubules that continue with the RER. This reticulum does not have ribosomes attached to its membrane, and this is why it is named smooth. Most of its proteins are synthesized in the RER. SER is abundant in those cells involved in fat metabolism, detoxification, and calcium storage.
• One of its functions is to produce membrane lipids, including glycerophospholipids and cholesterol.
• It is also responsible for the elimination of toxic products from the metabolism.
• SER is also involved in the dephosphorylation of glucose-6 phosphate, allowing glucose to be transported to the exterior of the cell.