Cell Biology - Plasma Membrane Structure
40 Questions
1 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 role do cell recognition proteins (Crp) primarily serve in the body?

  • Transporting molecules across the membrane
  • Facilitating cell-to-cell adhesion
  • Catalyzing chemical reactions
  • Distinguishing between self and foreign cells (correct)

    • Which type of protein directly participates in catalyzing metabolic reactions?

  • Receptor protein
  • Carriers protein
  • Enzymatic protein (correct)
  • Junction protein

    • Which junction type is characterized by strong connections that join intermediate filaments of neighboring cells?

  • Hemidesmosomes
  • Desmosomes (correct)
  • Tight junctions
  • Gap junctions

    • What is the primary function of receptor proteins?

    <p>To trigger cellular responses upon binding with signal molecules</p> Signup and view all the answers

    Which of the following junctions would you expect to contribute to the ability of cells to communicate?

    <p>Gap junctions</p> Signup and view all the answers

    What types of proteins are involved in forming junctions between cells?

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

    What important role does carnitine play in cellular metabolism?

    <p>Transporting fatty acids into mitochondria</p> Signup and view all the answers

    Which of the following statements about enzymatic proteins is true?

    <p>They are essential for conducting metabolic reactions.</p> Signup and view all the answers

    What is the primary function of the plasma membrane?

    <p>To regulate the entrance and exit of molecules</p> Signup and view all the answers

    Which component of the plasma membrane is responsible for controlling fluidity in animal cells?

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

    What do glycolipids consist of?

    <p>Lipids attached to carbohydrates</p> Signup and view all the answers

    What type of protein spans the membrane and can protrude from one or both sides?

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

    The fluid mosaic model describes the plasma membrane as having which characteristic?

    <p>Dynamic arrangement of phospholipids and proteins</p> Signup and view all the answers

    Which type of membrane protein facilitates the movement of specific molecules across the membrane?

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

    What is the role of carrier proteins in the plasma membrane?

    <p>To combine with substances to assist their movement</p> Signup and view all the answers

    What maintains the steady internal environment of a cell, regulated by the plasma membrane?

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

    What occurs to a plant cell in a hypotonic solution?

    <p>The central vacuole fills with water</p> Signup and view all the answers

    What is a characteristic of an isotonic solution?

    <p>No net gain or loss of water occurs</p> Signup and view all the answers

    In a hypertonic solution, what is the effect on an animal cell?

    <p>The cytoplasm shrinks due to water loss</p> Signup and view all the answers

    What happens to the chloroplasts in a plant cell placed in a hypertonic solution?

    <p>They cluster near the cell wall</p> Signup and view all the answers

    How does turgor pressure affect plant cells?

    <p>It keeps the plant erect</p> Signup and view all the answers

    What occurs to a plant cell in a hypotonic solution?

    <p>The central vacuole fills with water and turgor pressure develops.</p> Signup and view all the answers

    What is one consequence of cytolysis in animal cells?

    <p>Cells expand and may burst</p> Signup and view all the answers

    In which solution does no net movement of water occur?

    <p>Isotonic solution</p> Signup and view all the answers

    Which of the following solutions is associated with cell crenation in animal cells?

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

    What role do carrier proteins play in cellular transport?

    <p>They facilitate the passage of substances across the plasma membrane.</p> Signup and view all the answers

    What accurately describes the central vacuole's state in an isotonic solution?

    <p>It maintains its volume without pressure changes</p> Signup and view all the answers

    Active transport differs from facilitated transport in that active transport:

    <p>Requires ATP to move substances.</p> Signup and view all the answers

    What happens to a plant cell in a hypertonic solution?

    <p>The cytoplasm shrinks and chloroplasts are seen next to the cell wall.</p> Signup and view all the answers

    What is required for facilitated transport?

    <p>A concentration gradient and carrier proteins.</p> Signup and view all the answers

    Which of the following statements about osmosis is correct?

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

    What might trigger plasmolysis in plant cells?

    <p>Exposure to a hypertonic solution.</p> Signup and view all the answers

    What type of movement is facilitated by the sodium-potassium pump?

    <p>Movement of molecules against the concentration gradient</p> Signup and view all the answers

    What energy source is primarily utilized by the sodium-potassium pump?

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

    What role does the phosphate group play in the operation of the sodium-potassium pump?

    <p>It activates the carrier protein to change shape</p> Signup and view all the answers

    How many sodium ions are taken up by the carrier protein during one cycle of the sodium-potassium pump?

    <p>3</p> Signup and view all the answers

    What happens to the carrier protein after the phosphate group is released?

    <p>It resumes its original shape to release K+ ions</p> Signup and view all the answers

    What is the primary function of the sodium-potassium pump in nerve and muscle cells?

    <p>To create a negative charge inside cells</p> Signup and view all the answers

    What is a direct result of the activity of the sodium-potassium pump?

    <p>Maintaining a large excess of sodium ions outside the cell</p> Signup and view all the answers

    What change occurs to the carrier protein during the pump's process to facilitate ion transport?

    <p>It changes shape twice during the transport process</p> Signup and view all the answers

    Study Notes

    Plasma Membrane

    • Separates the cell's internal environment from its external environment.
    • Regulates molecule entry and exit, maintaining homeostasis.
    • In prokaryotic and eukaryotic cells, it's a phospholipid bilayer.
    • The fluid mosaic model describes embedded proteins within the bilayer, varying by cell type.
    • Composed of hydrophilic polar heads (facing inside and outside) and hydrophobic nonpolar tails (facing each other).
    • Cholesterol (in animal cells) regulates fluidity.
    • Membrane proteins can be peripheral (one side) or integral (spanning the membrane).
    • Both phospholipids and proteins can have attached carbohydrate chains (glycolipids and glycoproteins).

    Membrane Protein Functions

    • Channel proteins: Simple pores forming tunnels for specific molecules, allowing free movement across the membrane.
    • Carrier proteins (transport proteins): Assist molecule/ion movement across membranes, sometimes requiring ATP (e.g., carnitine carrying fatty acids into mitochondria).
    • Cell recognition proteins (CRPs): Glycoproteins enabling the body to distinguish between its own cells and others (e.g., MHC glycoproteins in the immune system).
    • Receptor proteins: Bind specific signal molecules, changing shape to trigger cellular responses (e.g., insulin receptor inducing glucose uptake).
    • Enzymatic proteins: Catalyze specific chemical reactions, directly participating in metabolic processes.
    • Junction/adhesion proteins: Connect cells, enabling communication; form various junctions between cells (tight junctions, adherens junctions, desmosomes, hemidesmosomes, gap junctions).

    Osmosis and Cell Environments

    • Isotonic solution: No net water gain or loss (0.9% NaCl).
    • Hypotonic solution: Cell gains water; animal cells undergo cytolysis (hemolysis); plant cells develop turgor pressure.
    • Hypertonic solution: Cell loses water; animal cells undergo crenation; plant cells undergo plasmolysis.

    Movement of Molecules: Transport by Carrier Proteins

    • The plasma membrane prevents/delays the passage of most substances.
    • Carrier proteins are specific, combining with molecules/ions to transport them across the membrane by changing shape.
    • Facilitated transport (passive transport): Molecules (like glucose or amino acids) move down their concentration gradient without ATP.
    • Active transport: Molecules move against their concentration gradient, requiring energy (usually ATP) and carrier proteins (e.g., Na+/K+ pump).

    Sodium-Potassium Pump

    • Moves Na+ out and K+ into cells, crucial for nerve and muscle cell function.
    • Involves ATP hydrolysis, causing conformational changes in the carrier protein to move ions.
    • Maintains Na+ excess outside and K+ excess inside the cell (essential for action potentials).

    Studying That Suits You

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

    Quiz Team

    Related Documents

    SBU1053 Chapter 3 Part I PDF - Cell Structures

    Description

    Explore the intricate structure and functions of the plasma membrane in cells. This quiz will cover the key concepts including the fluid mosaic model, the role of membrane proteins, and the importance of maintaining homeostasis. Test your understanding of both prokaryotic and eukaryotic cell membranes.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser