Questions and Answers
Which process describes the movement of proteins from the ER to the extracellular space?
Which of the following pathways involves the transport of materials from the extracellular space to the lysosome?
What is the main purpose of molecular chaperones in the ER?
Which of the following correctly sequences the steps of the exocytosis process?
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What is the role of glycosylation in the ER?
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How does the retrieval pathway function in vesicular transport?
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What structural change occurs to vesicles during their formation?
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Which of these statements about autophagy is correct?
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What is the primary function of the CFTR protein in epithelial cells?
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The CFTRΔF508 mutation causes what specific issue with the CFTR protein?
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What characteristic enables vesicle transport to facilitate protein trafficking?
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Which of the following processes is likely triggered by the accumulation of misfolded proteins in the ER?
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The vesicle transport mechanism is crucial because it prevents what potential problem in protein trafficking?
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How does ER quality control contribute to cellular health?
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Glycosylation is important because it primarily plays a role in what aspect of protein functionality?
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What happens to a significant percentage of polypeptides synthesized in the ER?
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What is the primary role of the coat on vesicles during transport?
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Which type of vesicle is responsible for transporting cargo from the Golgi to the endosome?
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Which vesicle type is involved in transporting proteins from the ER back to the Golgi?
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From which cellular location do COPII-coated vesicles primarily transport substances?
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What is the source of the cargo for retromer-coated vesicles?
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Which statement accurately characterizes COPI-coated vesicles?
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What is a key function of clathrin-coated vesicles?
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Which vesicular transport process is responsible for the movement of proteins synthesized in the ER to the Golgi apparatus?
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What does the retrograde transport mechanism primarily facilitate?
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Study Notes
Intracellular Protein Trafficking Pathways
- Biosynthetic-secretory pathway involves transport from Endoplasmic Reticulum (ER) to Golgi, then to extracellular space or endosome, and ultimately to lysosome.
- Retrieval pathway allows for recycling of proteins back to the ER or Golgi from endosomes.
- Endocytic pathway facilitates the movement of substances from extracellular space to endosomes and subsequently to lysosomes.
- Autophagy pathway involves the degradation of cytoplasmic components.
Key Steps in Vesicle Transport
- Transport vesicles form at specialized membrane regions, detached as coated vesicles.
- Vesicle transport allows exchange of contents between distinct membrane-enclosed compartments without direct membrane crossing.
Cystic Fibrosis Overview
- Cystic fibrosis is an autosomal recessive disorder resulting from mutations in the CFTR gene.
- The CFTR gene encodes a multi-spanning 1480 amino acid membrane protein that functions as a chloride channel in exocrine epithelial cells.
- CFTR is present in the apical membranes of various organs, including lungs, pancreas, and intestines.
Mutation Effects on CFTR
- CFTRΔF508 mutation leads to misfolding of the protein, preventing its transport to the plasma membrane and resulting in degradation within the ER.
- Quality control mechanisms in the ER ensure misfolded proteins do not interfere with normal protein function, causing a significant number of newly synthesized proteins to not reach their destinations.
- Accumulation of misfolded proteins can lead to an unfolded protein response (UPR), ER-associated degradation, and apoptosis.
Vesicle Transport Mechanisms
- Clathrin-coated vesicles transport from Golgi to endosomes and from plasma membrane to early endosomes.
- COPI-coated vesicles mediate retrograde transport from Golgi back to ER.
- COPII-coated vesicles facilitate anterograde transport from ER to Golgi.
- Retromer-coated vesicles transport from endosomes back to Golgi.
- Coats of vesicles select appropriate cargo molecules for transport, ensuring correct delivery across compartments.
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Description
This quiz covers the lumens and membranes of intracellular organelles such as the endoplasmic reticulum, Golgi apparatus, endosome, and lysosome. It also explores the biosynthetic-secretory pathways and vesicle transport mechanisms involved in protein trafficking. Test your knowledge of cell biology!