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Difficulty: HardCell Structure and Function

Proteins synthesized by free cytosolic ribosomes are packaged into transport vesicles and routed through the Golgi apparatus for extracellular secretion.

Answer: Answer

Answer

False. Free cytosolic ribosomes synthesize intracellular proteins, whereas secreted proteins are synthesized exclusively by ribosomes bound to the rough endoplasmic reticulum before moving to the Golgi apparatus.
Evaluating the statement as false is correct because the Golgi apparatus processes proteins delivered specifically from the rough endoplasmic reticulum. Free ribosomes translate proteins that remain in the cytoplasm or enter organelles like the nucleus and mitochondria directly without vesicular packaging.

Step-by-Step Solution

1
Identify the cellular sites of protein synthesis and their functional specialization.
Ribosomes exist either freely suspended in the cytosol or bound to the membrane of the rough endoplasmic reticulum.
The destination of a newly synthesized protein depends directly on where it is translated.
2
Trace the pathway required for extracellular secretion (the endomembrane secretory pathway).
Secretory proteins possess a signal peptide directing them to dock at the rough endoplasmic reticulum, from which they bud in vesicles to the cis-Golgi, undergo processing, and are targeted to the plasma membrane for exocytosis.
Vesicular trafficking requires luminal entry into the endoplasmic reticulum network.
3
Evaluate the role of free cytosolic ribosomes against the statement.
Free cytosolic ribosomes release their products directly into the cytosol, bypassing the endoplasmic reticulum and Golgi apparatus entirely.
Free ribosomes do not feed into the lumen of the endomembrane system, making the statement false.

Key Concept

Compartmentalization and the endomembrane secretory pathway versus cytosolic translation.
Estimated Time:1m 0s
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Topics

Cell Structure and Function

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