Cell Biology Membrane and Cytoskeleton Quiz
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Questions and Answers

Which statement accurately describes osmosis?

  • Water movement is always from an area of higher water concentration to lower water concentration. (correct)
  • Water moves from an area of lower solute concentration to higher solute concentration.
  • Water does not move through selectively permeable membranes.
  • Water moves against its concentration gradient.

    • What is the primary ion that is most abundant inside the cell?

  • Calcium cations
  • Potassium cations (correct)
  • Chloride anions
  • Sodium cations

    • What role does hydrostatic pressure play in the movement of water?

  • It is irrelevant to water movement in cells.
  • It creates a mechanical push that influences water flow. (correct)
  • It promotes water movement against the osmotic gradient.
  • It decreases the movement of water across membranes.

    • What characteristic of a membrane prevents the passage of solutes during osmosis?

    <p>Selectively permeable nature of the membrane</p> Signup and view all the answers

    Which statement correctly describes the distribution of sodium cations in relation to the cell?

    <p>Sodium cations are most abundant outside the cell.</p> Signup and view all the answers

    Which component of the cytoskeleton is responsible for the transport of vesicles within the cell?

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

    What type of protein are microtubules primarily composed of?

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

    Which of the following structures is involved in the formation of the cleavage furrow during cell division?

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

    How do intermediate filaments primarily contribute to cellular function?

    <p>Maintain cell shape</p> Signup and view all the answers

    Which type of cytoskeletal structure is primarily associated with muscle contraction?

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

    In the context of cell movement, what is the function of pseudopods?

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

    What is the main function of microtubules during cell division?

    <p>Form mitotic spindle</p> Signup and view all the answers

    Which component is NOT considered part of the cytoskeleton?

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

    What type of transmembrane protein is the LDL receptor classified as?

    <p>Type I transmembrane protein</p> Signup and view all the answers

    Which of the following molecules is considered impermeable to lipid membranes?

    <p>Most water-soluble compounds</p> Signup and view all the answers

    What characteristic distinguishes a type II transmembrane protein from a type I?

    <p>Carboxyl terminal on the exterior</p> Signup and view all the answers

    What role do detergents play in relation to membrane proteins?

    <p>They solubilise membrane proteins during purification</p> Signup and view all the answers

    Which type of compound can easily permeate a lipid membrane due to its solubility?

    <p>Lipids and gases</p> Signup and view all the answers

    What is a common feature of type III transmembrane proteins?

    <p>They do not have a cleavable signal sequence</p> Signup and view all the answers

    What is the role of ethanol in affecting membrane fluidity in the central nervous system?

    <p>Ethanol intercalates between membrane lipids, increasing fluidity.</p> Signup and view all the answers

    Which component is responsible for binding with the hydrophobic regions of membrane proteins?

    <p>Hydrophobic ends of detergents</p> Signup and view all the answers

    What is the primary function of the glycalyx of the plasma membrane?

    <p>To protect the cell against digestion and restrict uptake of certain compounds.</p> Signup and view all the answers

    Which type of transport requires energy to move molecules?

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

    What differentiates the Asialoglycoprotein Receptor from the LDL receptor?

    <p>Its carboxyl terminal is on the exterior</p> Signup and view all the answers

    What happens during the endocytosis of cholera toxin in the intestinal epithelial cells?

    <p>The toxin binds to Gm1-gangliosides and is then endocytosed in caveolae.</p> Signup and view all the answers

    Which of the following transport processes is specifically associated with water movement?

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

    What is a characteristic of passive transport?

    <p>It is influenced by the concentration gradient.</p> Signup and view all the answers

    What is the role of integral proteins in membrane function?

    <p>They serve as channels and receptors for signaling and transport.</p> Signup and view all the answers

    How do complex oligosaccharides on the glycalyx contribute to cellular function?

    <p>They can act as receptors for cell signaling.</p> Signup and view all the answers

    What is the main role of the nuclear pores?

    <p>To allow passage of molecules like mRNA in and out of the nucleus</p> Signup and view all the answers

    Which component is produced in the nucleolus?

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

    What characterizes the structure of the Golgi apparatus?

    <p>A stack of flat membranes with a cis and trans face</p> Signup and view all the answers

    How do the outer and inner nuclear membranes differ from the plasma membrane?

    <p>They consist of two phospholipid bilayers</p> Signup and view all the answers

    What is primarily modified by the Golgi apparatus?

    <p>Proteins and lipids</p> Signup and view all the answers

    The endoplasmic reticulum (ER) primarily functions to:

    <p>Synthesize and transport proteins and lipids</p> Signup and view all the answers

    What type of enzymes are associated with the functions occurring in the cytoplasm?

    <p>Intracellular enzymes</p> Signup and view all the answers

    Which of the following statements correctly describes chromatin?

    <p>It is DNA organized with proteins for structural support</p> Signup and view all the answers

    Study Notes

    Membrane Components

    • Cell membranes contain cholesterol and carbohydrates alongside phospholipids and proteins.

    Cytoskeleton Structure

    • Composed of fibrillar proteins organized into filaments or tubules.

    • Microtubules:

      • Made of tubulin proteins.
      • Supports the cell structure and acts as a framework.
      • Facilitates transport of vesicles/organelles.
      • Forms the mitotic spindle during cell division.
      • Aids in cell movement through structures like flagella and cilia.

    • Intermediate Filaments:

      • Provide structural support and help maintain cell shape (e.g., keratin).

    • Microfilaments:

      • Composed of actin proteins.
      • Responsible for pseudopod movement in cells.
      • Involved in muscle contraction and formation of the cleavage furrow during cell division.

    Nucleus Structure

    • Surrounded by the nuclear membrane, which compartmentalizes cytoplasm and nuclear space.
    • Nuclear Pores: Allow selective passage of molecules, especially mRNA.
    • Nucleoplasm: Contains the nucleolus (site of rRNA synthesis) and DNA in the form of chromatin.

    Golgi Apparatus

    • Structure consists of flattened vesicles (cisternae) with two distinct faces:
      • Cis Face: Receives materials from the endoplasmic reticulum (ER).
      • Trans Face: Packages and releases materials to the cell membrane.
    • Functions in modifying proteins and lipids before they are transported.

    Endoplasmic Reticulum (ER)

    • Made up of membrane-bound structures.
    • Rough ER (RER): Studded with ribosomes; involved in protein synthesis.
    • Smooth ER (SER): Lacks ribosomes; involved in lipid synthesis and detoxification.
    • Semi-permeable to lipids and gas molecules; impermeable to most water-soluble substances.

    Membrane Transport

    • Two primary types of transport:
      • Passive Transport: Requires no energy; substances move from high to low concentration (e.g., diffusion, osmosis, facilitated diffusion).
      • Active Transport: Requires energy; substances move from low to high concentration, aided by pumps.

    Glycocalyx of Plasma Membrane

    • Composed of short chains of carbohydrates (oligosaccharides) that extend into the extracellular environment.
    • Provides protection against digestion and restricts uptake of hydrophobic compounds.

    Osmosis and Hydrostatic Pressure

    • Water movement occurs from areas of higher water concentration to lower concentration through a semi-permeable membrane.
    • Hydrostatic pressure is the mechanical pressure created by fluid movement.

    Ionic Steady States

    • Potassium cations are most abundant inside cells, while sodium cations are prevalent outside cells.
    • Chloride ions are primarily found outside the cell.

    Cell Permeability

    • Passive transport relies on carrier proteins to mediate substance movement across membranes, with selective permeability impacting cellular function.

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    Description

    Test your knowledge on the key components of cell membranes, the structure of the cytoskeleton, and the functions of microtubules, intermediate filaments, and microfilaments. Understand how these cellular structures contribute to cell shape, transport, and movement. Dive into the details of the nucleus and its surrounding membrane.

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