Cell Biology: Endomembrane System and Membrane-Enclosed Organelles

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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?

Vesicular transport (D) Signup and view all the answers

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

Nearly half (B) 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?

Exocytosis (A) Signup and view all the answers

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

Phagocytosis (D) Signup and view all the answers

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

Vesicle budding and fusion (B) Signup and view all the answers

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

Mitochondria (D) Signup and view all the answers

How do membrane-enclosed organelles enlarge as cells grow?

By incorporating new molecules (B) Signup and view all the answers

What is the fate of organelles during cell division?

They are distributed between the two daughter cells (A) Signup and view all the answers

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

Protein modification and sorting (C) Signup and view all the answers

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

Engulfment of bacteria by primitive pre-eukaryotic cells (A) Signup and view all the answers

What is the continuous process by which cells produce proteins?

Protein synthesis (B) Signup and view all the answers

Where does the synthesis of virtually all proteins begin?

Cytosol (A) Signup and view all the answers

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

To direct proteins to the correct compartment (B) Signup and view all the answers

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

Peroxisomes (B) Signup and view all the answers

What is the mechanism by which proteins enter the nucleus?

Transport through nuclear pores (A) Signup and view all the answers

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

Basic (D) Signup and view all the answers

Which organelles receive proteins directly from the cytosol?

Mitochondria, chloroplasts, and nucleus (A) Signup and view all the answers

What is the primary function of protein translocators?

To direct proteins to the correct compartment (B) Signup and view all the answers

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

To target proteins to specific organelles (C) Signup and view all the answers

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

Mitochondrion (C) Signup and view all the answers

What is the role of chaperones in protein transport?

To pull proteins across membranes (B) Signup and view all the answers

What is the primary mechanism of nuclear transport?

Nuclear import/export proteins (A) Signup and view all the answers

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

They are translocated across the organelle membrane (D) Signup and view all the answers

Which of the following processes drives nuclear transport?

GTP hydrolysis (C) Signup and view all the answers

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

To translocate proteins across membranes (B) Signup and view all the answers

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

To selectively allow the passage of macromolecules (C) Signup and view all the answers

What is theENERGY source that drives nuclear transport?

GTP hydrolysis (C) Signup and view all the answers

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

Nuclear Localization Signal (D) Signup and view all the answers

What is the function of Ran in nuclear transport?

To regulate nuclear transport (B) Signup and view all the answers

What is the characteristic of proteins transported through nuclear pores?

They are in their fully folded conformation (D) 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?

Nuclear meshwork (D) Signup and view all the answers

What is the direction of protein transport that requires energy?

From the cytosol to the nucleus (A) Signup and view all the answers

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

To direct proteins from the cytosol to the nucleus (B) Signup and view all the answers

What is the characteristic of the nuclear pore complex?

It selectively allows passage of macromolecules (D) Signup and view all the answers

What determines the direction of protein transport through nuclear pores?

Ran concentration (C) Signup and view all the answers