Multiple Choice
Which membrane-enclosed organelle primarily functions as a storage compartment for water, ions, nutrients, and waste products in eukaryotic cells?
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13. Intracellular Protein Transport
Membrane Enclosed Organelles
Multiple Choice
In eukaryotic cells, what is the key structural and functional difference between rough endoplasmic reticulum (rough ER) and smooth endoplasmic reticulum (smooth ER)?
A
Rough ER is surrounded by a double membrane and contains DNA, whereas smooth ER is a single-membrane organelle that packages proteins for secretion.
B
Rough ER is the primary site of ATP production, whereas smooth ER contains the enzymes for glycolysis.
C
Rough ER lacks ribosomes and primarily carries out lipid synthesis, whereas smooth ER is covered with ribosomes and synthesizes secreted proteins.
D
Rough ER is studded with ribosomes and is a major site of synthesis/processing for secreted and membrane proteins, whereas smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification.
Verified step by step guidance1
Identify the main structural difference between rough ER and smooth ER: Rough ER is studded with ribosomes on its cytoplasmic surface, while smooth ER lacks ribosomes.
Understand the functional role of rough ER: Because of the ribosomes, rough ER is primarily involved in the synthesis and processing of proteins that are destined for secretion, insertion into membranes, or lysosomes.
Recognize the functional role of smooth ER: Smooth ER is involved in lipid synthesis, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions.
Note that both rough and smooth ER are single-membrane organelles, so the statement about rough ER having a double membrane and containing DNA is incorrect.
Summarize the key difference: Rough ER's ribosome-studded surface enables protein synthesis for export or membrane insertion, whereas smooth ER's ribosome-free surface specializes in lipid-related functions and detoxification.
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