Cytoskeleton and Its Components
37 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary function of cholesterol molecules in the cell membrane?

  • Catalyze production of enzymes
  • Maintain membrane fluidity (correct)
  • Form hydrogen bonds with water
  • Facilitate passive transport

    • Which term describes the movement of water across a selectively permeable membrane?

  • Active transport
  • Endocytosis
  • Facilitated diffusion
  • Osmosis (correct)

    • What type of transport moves molecules against their concentration gradient?

  • Active transport (correct)
  • Facilitated diffusion
  • Diffusion
  • Passive transport

    • Which of the following correctly describes passive transport?

    <p>Moves substances from high to low concentration</p> Signup and view all the answers

    What is the role of glycoproteins in the cell membrane?

    <p>Identify cell type</p> Signup and view all the answers

    Which of the following is NOT a method of molecule movement into cells?

    <p>Diffusion through solid barriers</p> Signup and view all the answers

    Which of these statements is true regarding diffusion?

    <p>It results in the equalization of concentrations.</p> Signup and view all the answers

    What drives passive transport mechanisms?

    <p>Concentration gradients</p> Signup and view all the answers

    What are the main components of the cytoskeleton?

    <p>Microfilaments, Microtubules, Intermediate filaments</p> Signup and view all the answers

    Which function is NOT attributed to the cytoskeleton?

    <p>Energy production</p> Signup and view all the answers

    Which characteristic distinguishes intermediate filaments from microfilaments and microtubules?

    <p>Size range between microfilaments and microtubules</p> Signup and view all the answers

    What type of filament is primarily involved in muscle contractions?

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

    Which function is associated with microtubules?

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

    Which structural component forms the main barrier of the cell membrane?

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

    Which of the following is NOT a function of the cell membrane?

    <p>Synthesizing proteins</p> Signup and view all the answers

    What type of movement do cilia facilitate?

    <p>Wave-like motion</p> Signup and view all the answers

    What is the primary function of active transport?

    <p>To move substances against their concentration gradient using energy</p> Signup and view all the answers

    Which type of endocytosis specifically involves the engulfing of large particles?

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

    What role do protein pumps play in cellular processes?

    <p>They require energy to move substances across membranes</p> Signup and view all the answers

    What occurs during exocytosis?

    <p>The cell releases large molecules by discharging material</p> Signup and view all the answers

    Which of the following statements about receptor-mediated endocytosis is accurate?

    <p>It involves the specific uptake of molecules via receptors</p> Signup and view all the answers

    What distinguishes facilitated diffusion from simple diffusion?

    <p>Facilitated diffusion requires carrier proteins.</p> Signup and view all the answers

    Which of the following best describes osmosis?

    <p>The movement of water through a permeable membrane to a higher concentration of solutes.</p> Signup and view all the answers

    What requirement does facilitated diffusion have that simple diffusion does not?

    <p>Carrier proteins</p> Signup and view all the answers

    What happens to a cell in a hypotonic solution?

    <p>The cell swells and may burst due to excess water intake.</p> Signup and view all the answers

    What primarily drives the process of diffusion?

    <p>The need for balance in solute concentrations.</p> Signup and view all the answers

    How does a hypertonic solution affect a cell?

    <p>Water exits the cell, causing it to shrink.</p> Signup and view all the answers

    What type of molecules typically undergo facilitated diffusion?

    <p>Larger polar molecules</p> Signup and view all the answers

    Which of the following statements about facilitated diffusion is false?

    <p>It is an active transport mechanism.</p> Signup and view all the answers

    What occurs when a cell is placed in an isotonic solution?

    <p>No net movement of water occurs.</p> Signup and view all the answers

    What happens to a cell in a hypotonic solution?

    <p>Water diffuses into the cell, potentially causing it to swell.</p> Signup and view all the answers

    In which type of solution does water diffuse out of the cell?

    <p>Hypertonic solution.</p> Signup and view all the answers

    What is required for active transport to occur?

    <p>Chemical energy from ATP.</p> Signup and view all the answers

    What is the main characteristic of a hypertonic solution?

    <p>High concentration of solutes relative to another solution.</p> Signup and view all the answers

    Which solution will cause a cell to burst due to excess water intake?

    <p>Hypotonic solution.</p> Signup and view all the answers

    What does active transport create in the cell membrane?

    <p>A charge gradient.</p> Signup and view all the answers

    When a cell is in an isotonic environment, what happens to its volume?

    <p>It remains constant.</p> Signup and view all the answers

    Study Notes

    Cytoskeleton

    • A microscopic network of protein filaments and tubules in the cytoplasm
    • Consists of three main types of filaments, which are elongated chains of protein:
      • Microfilaments
      • Microtubules
      • Intermediate Filaments
    • Supports the cell, gives the cell its shape, and facilitates movement
    • Plays important roles in molecule transport and cell division

    Microfilaments

    • Primarily composed of the protein actin
    • Involved in multiple cellular processes, including:
      • Cytokinesis (cytoplasm division)
      • Cell motility
      • Cytoplasmic streaming
      • Muscle contractions
      • Maintenance of cell shape

    Microtubules

    • Involved in a variety of important cellular processes, including:
      • Chromosome division during cell division
      • Transporting molecules within the cell
      • Maintenance of cell shape
      • Cell motility

    Cilia and Flagella

    • Flagella are "tails" that propel a cell forward
    • Cilia are cellular appendages that allow the cell to move

    Intermediate Filaments

    • Intermediate in size between microfilaments and microtubules (8-10 nm)
    • Composed of various proteins like keratin, vimentin, desmin, and lamin
    • Play a crucial role in maintaining cell shape
    • Provide structural support by bearing tension

    Cell Membrane

    • Also known as the plasma membrane
    • Encloses the cell and its organelles
    • Phospholipids form the basic structure of the cell membrane, creating a lipid bilayer with embedded proteins
    • Involved in five key functions:
      • Protects the cell by acting as a barrier
      • Regulates transport of substances into and out of the cell
      • Receives chemical messengers from other cells
      • Acts as a receptor
      • Cell mobility, secretions, and absorptions of substances

    Structure of the Cell Membrane

    • Contains various components that aid in its function:
      • Channels or transporters: move molecules in one direction
      • Receptors: recognize specific chemicals
      • Cholesterol molecules: keeps the membrane fluid consistent
      • Enzymes: catalyze production of substances
      • Glycoproteins: identify cell type

    Phospholipids in the Cell Membrane

    • Have a hydrophilic (head) and hydrophobic (tail)
    • Hydrophilic head has affinity for water
    • Hydrophobic tail repels water
    • This interaction of phospholipids with water is crucial for life

    Movement Across the Plasma Membrane

    • Some molecules can move across the cell membrane without assistance:
      • Water, Carbon dioxide, Ammonia, Oxygen
    • Other molecules need different transport mechanisms:

    Methods of Molecule Movement into Cells

    • Passive transport: moves chemicals from high to low concentration (does not require energy)
    • Active transport: moves chemicals from low to high concentration (requires energy, uses protein pumps)
    • Endocytosis: movement of large materials into cells
    • Exocytosis: movement of large materials out of the cells

    Passive Transport

    • Moves chemicals down their concentration gradient
    • Three types of passive transport:
      • Diffusion
      • Facilitated Diffusion
      • Osmosis

    Diffusion

    • Movement of molecules from high concentration to low concentration to equalize concentration
    • Requires no energy
    • Driven by the existing concentration gradient

    Facilitated Diffusion

    • Passive transport of molecules or ions through specific transmembrane integral proteins
    • Does not require energy but needs carrier proteins
    • Moves molecules from high to low concentration

    Osmosis

    • Movement of water across a semipermeable membrane
    • Water moves from a dilute solution to a concentrated solution
    • Important for water movement in and out of cells

    Osmosis vs Diffusion

    • Osmosis is the movement of solvent particles (water molecules)
    • Diffusion is the movement of particles (like oxygen)

    Hypotonic, Hypertonic, and Isotonic Solutions

    • Hypotonic: lower solute concentration than the cell, water moves into the cell, causing it to swell
    • Hypertonic: higher solute concentration than the cell, water moves out of the cell, causing it to shrink
    • Isotonic: equal solute concentration inside and outside the cell, water moves in and out at the same rate, equilibrium

    Active Transport

    • Moves chemicals against their concentration gradient
    • Requires energy to move chemicals from low to high
    • Creates a charge gradient across the cell membrane
    • Requires protein pumps to move chemicals

    Endocytosis

    • Movement of large materials into cells
    • Three types of endocytosis:
      • Bulk-phase (non-specific)
      • Receptor-mediated (specific)
      • Receptor-mediated endocytosis uses phagocytosis and pinocytosis processes

    Receptor-Mediated Endocytosis

    • How cells take in specific molecules by binding to receptors on the cell surface

    Phagocytosis

    • "Cell eating"
    • Engulfing large particles or organisms by the cell

    Pinocytosis

    • "Cell drinking"
    • Engulfing dissolved materials by the cell

    Exocytosis

    • The reverse of endocytosis
    • Cell discharges materials
    • Vesicle containing the material moves to cell surface
    • Membrane of vesicle fuses with cell membrane
    • Materials are expelled outside the cell.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Lec3 Membrane Structure & Function 2 PDF

    Description

    Explore the intricate structure and function of the cytoskeleton, including microfilaments, microtubules, and intermediate filaments. Understand how these components support cell shape, movement, and essential cellular processes such as division and transport.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser