Cell Membrane Structure and Function
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Questions and Answers

What is the structure of the cell membrane described as?

  • Rigid Structure Model
  • Solid Barrier Model
  • Fluid Mosaic Model (correct)
  • Layered Membrane Model

    • The cell membrane is found in only plant cells.

    False (B)

    Name one basic molecule found in the cell membrane.

    Phospholipids

    The molecules in the cell membrane can flow like a _____ .

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

    Match the following components with their role in the cell membrane:

    <p>Phospholipids = Form a bilayer Proteins = Transport substances Cholesterol = Stabilizes membrane fluidity Carbohydrates = Cell recognition</p> Signup and view all the answers

    Which of the following is NOT one of the basic molecules in the cell membrane?

    <p>Nucleic acids (D)</p> Signup and view all the answers

    The Fluid Mosaic Model indicates that molecules in the cell membrane are fixed in place.

    <p>False (B)</p> Signup and view all the answers

    What type of model explains the structure of the cell membrane?

    <p>Fluid Mosaic Model</p> Signup and view all the answers

    The phospholipid bilayer consists of 2 layers of ________________________.

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

    Which of the following types of molecules can easily pass through the phospholipid bilayer?

    <p>Oxygen (D)</p> Signup and view all the answers

    Phospholipids are hydrophobic and do not interact with water.

    <p>True (A)</p> Signup and view all the answers

    What does the term 'selectively permeable' refer to in the context of cell membranes?

    <p>It refers to the ability of the membrane to allow certain molecules to pass while blocking others.</p> Signup and view all the answers

    Only _______________ molecules are able to ____________ __________ membrane.

    <p>nonpolar, pass through</p> Signup and view all the answers

    Which of the following is an example of a molecule that cannot directly pass through the phospholipid bilayer?

    <p>Amino acids (B)</p> Signup and view all the answers

    Match the following types of proteins with their functions in the cell membrane:

    <p>Transport Proteins = Transport molecules across the membrane Anchor Proteins = Attach the membrane to external structures Receptor Proteins = Bind signaling molecules to trigger a response Channel Proteins = Provide passageways for ions and small molecules</p> Signup and view all the answers

    Water can pass through the membrane freely without any assistance.

    <p>False (B)</p> Signup and view all the answers

    What type of proteins are permanently stuck in the membrane?

    <p>Transmembrane proteins (C)</p> Signup and view all the answers

    Cholesterol decreases the stability and movement of the cell membrane.

    <p>False (B)</p> Signup and view all the answers

    What do glycoproteins and glycolipids provide to a cell?

    <p>Sugar nametags or identification markers</p> Signup and view all the answers

    Diffusion is the movement of molecules from a region of high concentration to a region of low concentration. This movement is called a __________ concentration gradient.

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

    Which type of protein only adheres to one side of the membrane?

    <p>Peripheral proteins (C)</p> Signup and view all the answers

    Aquaporins are specialized channels that facilitate the movement of __________ across the cell membrane.

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

    Match the following proteins with their function:

    <p>Receptor Proteins = Receive signals Enzymes = Catalyze reactions Glycoproteins = Identify/mark cells Aquaporins = Facilitate water transport</p> Signup and view all the answers

    Water, being small but polar, diffuses rapidly across cell membranes without the help of channels.

    <p>False (B)</p> Signup and view all the answers

    Osmosis is the diffusion of __________ across a _________ _________.

    Signup and view all the answers

    Osmosis is the diffusion of __________ across a _________ _________.

    Signup and view all the answers

    Osmosis is the diffusion of __________ across a _________ _________.

    Signup and view all the answers

    Study Notes

    Cell Membrane

    • The cell membrane is also known as the plasma membrane
    • The cell membrane is super important for all cells
    • The cell membrane follows the Fluid Mosaic Model: molecules are not fixed, but move like a fluid
    • 3 basic molecules in the cell membrane:
      • Phospholipids
      • Proteins
      • Cholesterol

    Structure of the Cell Membrane

    • The cell membrane has a phospholipid bilayer: 2 layers of phospholipid molecules
    • Phospholipids have a hydrophilic (water-loving) head and a hydrophobic (water-fearing) tail.
    • The cell membrane is selectively permeable, meaning only small molecules can pass through
    • The hydrophobic tails of phospholipids prevent large or polar molecules from passing through
    • The cell membrane is semipermeable, meaning it lets some things through but not others
    • Examples of molecules that can pass through the cell membrane: oxygen, carbon dioxide, water
    • Examples of molecules that cannot pass through the cell membrane: amino acids, carbohydrates (glucose), ions
    • Surface proteins can be used for different functions:
      • Transport (transport proteins/ion channels)
      • Binding/attaching (anchor proteins)
      • Receiving signals (receptor proteins with binding pockets for signaling molecules)
      • Catalyzing reactions (enzymes)
      • Identifying/marking (glycoproteins with sugar "nametags")
    • There are two types of surface proteins: integral proteins and peripheral proteins
      • Integral proteins are permanently stuck in the membrane
      • Peripheral proteins only adhere to one side of the membrane.
    • Cholesterol keeps the membrane from becoming too rigid or too fluid
    • Cholesterol increases both stability and movement of the membrane
    • Cholesterol is a type of lipid

    Movement Across the Cell Membrane

    • Movement across the cell membrane happens by diffusion, osmosis, and active transport
    • Diffusion: movement of molecules from high concentration to low concentration
    • Diffusion is passive transport: no energy is required
    • Osmosis: diffusion of water across a selectively permeable membrane
    • Water moves from an area of high water concentration/low solute concentration to an area of low water concentration/high solute concentration
    • Osmosis requires active transport
    • Passive transport requires no energy to move molecules across the membrane
    • Active transport requires energy to move molecules across the membrane
    • Facilitated diffusion uses a protein to help molecules go through the cell membrane
    • Facilitated diffusion is passive transport because it does not require energy
    • Dynamic Equilibrium: movement of water continues, but net movement is zero
    • Hypertonic Solution: higher solute concentration in the solution than in the cell.
    • Isotonic Solution: same amount of solute in the solution as in the cell
    • Hypotonic solution: lower solute concentration in solution than in the cell

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    Related Documents

    Cell Transport Notes PDF

    Description

    This quiz explores the essential components and functions of the cell membrane, also known as the plasma membrane. You'll learn about the Fluid Mosaic Model, the phospholipid bilayer, and the semipermeable nature of the membrane, as well as the molecules that can cross it. Test your knowledge on cell membrane biology!

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