Multiple Choice
In the context of ER processing and transport, the rough endoplasmic reticulum (RER) is the portion of the ER that primarily:
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13. Intracellular Protein Transport
ER Processing and Transport
Multiple Choice
In eukaryotic cells, what is the primary function of the rough endoplasmic reticulum (rough ER)?
A
Breakdown of macromolecules via hydrolytic enzymes in an acidic lumen
B
Synthesis and initial processing (folding and modification) of proteins destined for secretion, membranes, or lysosomes
C
Synthesis of most cytosolic proteins by free ribosomes
D
ATP production through oxidative phosphorylation on the inner mitochondrial membrane
Verified step by step guidance1
Identify the rough endoplasmic reticulum (rough ER) as a membrane-bound organelle studded with ribosomes on its cytosolic surface, which gives it a 'rough' appearance under the microscope.
Understand that the ribosomes attached to the rough ER are responsible for synthesizing proteins that are destined for secretion outside the cell, incorporation into cellular membranes, or delivery to lysosomes.
Recognize that after synthesis, these proteins enter the lumen of the rough ER where they undergo initial processing steps such as folding and post-translational modifications (e.g., glycosylation).
Distinguish the rough ER's function from other organelles: it is not involved in hydrolytic breakdown (which occurs in lysosomes), cytosolic protein synthesis (which occurs on free ribosomes), or ATP production (which occurs in mitochondria).
Conclude that the primary function of the rough ER is the synthesis and initial processing of proteins destined for secretion, membranes, or lysosomes.
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