Cell Biology: Endomembrane System and Membrane-Enclosed Organelles
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Questions and Answers

What is the primary function of smooth ER in eukaryotic cells?

  • Storage of genetic material
  • Assembly of peroxisomes
  • Steroid hormone synthesis and detoxification (correct)
  • Protein synthesis
  • How did the nuclear membrane and ER originate in eukaryotic cells?

  • They evolved from invaginations of the plasma membrane (correct)
  • They were generated de novo through a complex series of mutations
  • They were formed through the fusion of smaller organelles
  • They were inherited from prokaryotic ancestors
  • What is the term for the process by which cells take in external materials through the formation of vesicles?

  • Endocytosis (correct)
  • Pinocytosis
  • Phagocytosis
  • Exocytosis
  • What is the primary mechanism by which proteins are sorted and transported to their correct destinations in eukaryotic cells?

    <p>Vesicular transport</p> Signup and view all the answers

    What percentage of the volume of a eukaryotic cell is occupied by organelles?

    <p>Nearly half</p> Signup and view all the answers

    What is the term for the movement of molecules out of the cell through the fusion of vesicles with the plasma membrane?

    <p>Exocytosis</p> Signup and view all the answers

    What is the term for the process by which cells engulf and digest foreign particles and debris?

    <p>Phagocytosis</p> Signup and view all the answers

    What is the primary mechanism by which individual membrane systems in the endomembrane system communicate with each other?

    <p>Vesicle budding and fusion</p> Signup and view all the answers

    Which of the following organelles has its own genome and can make a subset of its own proteins?

    <p>Mitochondria</p> Signup and view all the answers

    How do membrane-enclosed organelles enlarge as cells grow?

    <p>By incorporating new molecules</p> Signup and view all the answers

    What is the fate of organelles during cell division?

    <p>They are distributed between the two daughter cells</p> Signup and view all the answers

    What is the primary function of the endoplasmic reticulum in the endomembrane system?

    <p>Protein modification and sorting</p> Signup and view all the answers

    Which of the following is a theory of how membrane-enclosed organelles evolved?

    <p>Engulfment of bacteria by primitive pre-eukaryotic cells</p> Signup and view all the answers

    What is the continuous process by which cells produce proteins?

    <p>Protein synthesis</p> Signup and view all the answers

    Where does the synthesis of virtually all proteins begin?

    <p>Cytosol</p> Signup and view all the answers

    What is the main function of signal sequences in protein sorting?

    <p>To direct proteins to the correct compartment</p> Signup and view all the answers

    Which organelle acquires some of its membrane proteins from the ER, but the majority from the cytosol?

    <p>Peroxisomes</p> Signup and view all the answers

    What is the mechanism by which proteins enter the nucleus?

    <p>Transport through nuclear pores</p> Signup and view all the answers

    What type of amino acids are typically found in nuclear signal sequences?

    <p>Basic</p> Signup and view all the answers

    Which organelles receive proteins directly from the cytosol?

    <p>Mitochondria, chloroplasts, and nucleus</p> Signup and view all the answers

    What is the primary function of protein translocators?

    <p>To direct proteins to the correct compartment</p> Signup and view all the answers

    What is the primary function of signal sequences in protein sorting?

    <p>To target proteins to specific organelles</p> Signup and view all the answers

    Which of the following organelles has a double membrane structure that must be crossed during protein transport?

    <p>Mitochondrion</p> Signup and view all the answers

    What is the role of chaperones in protein transport?

    <p>To pull proteins across membranes</p> Signup and view all the answers

    What is the primary mechanism of nuclear transport?

    <p>Nuclear import/export proteins</p> Signup and view all the answers

    What is the fate of proteins that unfold to enter mitochondria and chloroplasts?

    <p>They are translocated across the organelle membrane</p> Signup and view all the answers

    Which of the following processes drives nuclear transport?

    <p>GTP hydrolysis</p> Signup and view all the answers

    What is the primary function of protein translocators in protein sorting?

    <p>To translocate proteins across membranes</p> Signup and view all the answers

    What is the primary function of nuclear pores in the nuclear envelope?

    <p>To selectively allow the passage of macromolecules</p> Signup and view all the answers

    What is theENERGY source that drives nuclear transport?

    <p>GTP hydrolysis</p> Signup and view all the answers

    What is the name of the sequence that directs a protein from the cytosol into the nucleus?

    <p>Nuclear Localization Signal</p> Signup and view all the answers

    What is the function of Ran in nuclear transport?

    <p>To regulate nuclear transport</p> Signup and view all the answers

    What is the characteristic of proteins transported through nuclear pores?

    <p>They are in their fully folded conformation</p> Signup and view all the answers

    What is the meshwork of proteins in the nuclear envelope that allows small water-soluble molecules to pass freely?

    <p>Nuclear meshwork</p> Signup and view all the answers

    What is the direction of protein transport that requires energy?

    <p>From the cytosol to the nucleus</p> Signup and view all the answers

    What is the purpose of the nuclear localization signal (NLS)?

    <p>To direct proteins from the cytosol to the nucleus</p> Signup and view all the answers

    What is the characteristic of the nuclear pore complex?

    <p>It selectively allows passage of macromolecules</p> Signup and view all the answers

    What determines the direction of protein transport through nuclear pores?

    <p>Ran concentration</p> Signup and view all the answers

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