38 Questions
What is the primary function of smooth ER in eukaryotic cells?
Steroid hormone synthesis and detoxification
How did the nuclear membrane and ER originate in eukaryotic cells?
They evolved from invaginations of the plasma membrane
What is the term for the process by which cells take in external materials through the formation of vesicles?
Endocytosis
What is the primary mechanism by which proteins are sorted and transported to their correct destinations in eukaryotic cells?
Vesicular transport
What percentage of the volume of a eukaryotic cell is occupied by organelles?
Nearly half
What is the term for the movement of molecules out of the cell through the fusion of vesicles with the plasma membrane?
Exocytosis
What is the term for the process by which cells engulf and digest foreign particles and debris?
Phagocytosis
What is the primary mechanism by which individual membrane systems in the endomembrane system communicate with each other?
Vesicle budding and fusion
Which of the following organelles has its own genome and can make a subset of its own proteins?
Mitochondria
How do membrane-enclosed organelles enlarge as cells grow?
By incorporating new molecules
What is the fate of organelles during cell division?
They are distributed between the two daughter cells
What is the primary function of the endoplasmic reticulum in the endomembrane system?
Protein modification and sorting
Which of the following is a theory of how membrane-enclosed organelles evolved?
Engulfment of bacteria by primitive pre-eukaryotic cells
What is the continuous process by which cells produce proteins?
Protein synthesis
Where does the synthesis of virtually all proteins begin?
Cytosol
What is the main function of signal sequences in protein sorting?
To direct proteins to the correct compartment
Which organelle acquires some of its membrane proteins from the ER, but the majority from the cytosol?
Peroxisomes
What is the mechanism by which proteins enter the nucleus?
Transport through nuclear pores
What type of amino acids are typically found in nuclear signal sequences?
Basic
Which organelles receive proteins directly from the cytosol?
Mitochondria, chloroplasts, and nucleus
What is the primary function of protein translocators?
To direct proteins to the correct compartment
What is the primary function of signal sequences in protein sorting?
To target proteins to specific organelles
Which of the following organelles has a double membrane structure that must be crossed during protein transport?
Mitochondrion
What is the role of chaperones in protein transport?
To pull proteins across membranes
What is the primary mechanism of nuclear transport?
Nuclear import/export proteins
What is the fate of proteins that unfold to enter mitochondria and chloroplasts?
They are translocated across the organelle membrane
Which of the following processes drives nuclear transport?
GTP hydrolysis
What is the primary function of protein translocators in protein sorting?
To translocate proteins across membranes
What is the primary function of nuclear pores in the nuclear envelope?
To selectively allow the passage of macromolecules
What is theENERGY source that drives nuclear transport?
GTP hydrolysis
What is the name of the sequence that directs a protein from the cytosol into the nucleus?
Nuclear Localization Signal
What is the function of Ran in nuclear transport?
To regulate nuclear transport
What is the characteristic of proteins transported through nuclear pores?
They are in their fully folded conformation
What is the meshwork of proteins in the nuclear envelope that allows small water-soluble molecules to pass freely?
Nuclear meshwork
What is the direction of protein transport that requires energy?
From the cytosol to the nucleus
What is the purpose of the nuclear localization signal (NLS)?
To direct proteins from the cytosol to the nucleus
What is the characteristic of the nuclear pore complex?
It selectively allows passage of macromolecules
What determines the direction of protein transport through nuclear pores?
Ran concentration
Learn about the components of the endomembrane system, including the nuclear membrane, ER, Golgi, endosomes, peroxisomes, and lysosomes. Understand how they interact with each other and how membrane-enclosed organelles evolved from engulfed bacteria.
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