Cell Membrane Function and Structure
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Questions and Answers

What type of molecules can pass through the cell membrane quickly?

  • Charged molecules
  • Large and nonpolar molecules
  • Small and nonpolar molecules (correct)
  • Small and polar molecules
  • Why does the cell membrane allow small molecules to pass through?

  • Because they are small enough to sneak by (correct)
  • Because they are charged
  • Because they are nonpolar
  • Because they are polar
  • What is the main reason why glucose cannot pass through the cell membrane?

  • Because it is large and nonpolar
  • Because it is small and nonpolar
  • Because it is small and charged
  • Because it is large and polar (correct)
  • What is the property of the cell membrane that determines what enters and leaves?

    <p>Semi-permeability</p> Signup and view all the answers

    What is the main component of the cell membrane?

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

    Why did scientists stop using benzene to wash their hands?

    <p>Because it can pass through the cell membrane and cause harm</p> Signup and view all the answers

    What is the reason why charged molecules cannot pass through the cell membrane?

    <p>Because they are too polar</p> Signup and view all the answers

    What is the main function of the cell membrane?

    <p>To protect the cell from the outside environment and determine what can enter and leave</p> Signup and view all the answers

    What is the term for the property of the cell membrane that allows some substances to pass through while others cannot?

    <p>Semi-permeability</p> Signup and view all the answers

    What type of molecules are preferred by the cell membrane?

    <p>Small and nonpolar molecules</p> Signup and view all the answers

    What is the main building block of the cell membrane?

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

    What is the function of the glycerol backbone in a phospholipid?

    <p>It holds the fatty acid tails to the phosphate head group</p> Signup and view all the answers

    What is the purpose of the phosphate head group in a phospholipid?

    <p>It is hydrophilic and interacts with water</p> Signup and view all the answers

    What are the two fatty acid tails in a phospholipid?

    <p>Hydrophobic parts of the phospholipid that do not interact with water</p> Signup and view all the answers

    What is the result of the cell membrane being semi-permeable?

    <p>The cell is able to regulate its internal environment</p> Signup and view all the answers

    Why is the cell membrane important for our survival?

    <p>It allows the cell to regulate its internal environment</p> Signup and view all the answers

    What is the term for a molecule that has both hydrophobic and hydrophilic sections?

    <p>Amphipathic molecule</p> Signup and view all the answers

    What is the primary reason why the fatty acid tails in a phospholipid bilayer want to stay away from water?

    <p>They are hydrophobic</p> Signup and view all the answers

    What is the shape of the cell membrane in a real-life cell?

    <p>A circle</p> Signup and view all the answers

    What is the term for the movement of small, nonpolar molecules through the cell membrane?

    <p>Passive diffusion</p> Signup and view all the answers

    What is an example of a small nonpolar molecule that can pass through the cell membrane?

    <p>O2</p> Signup and view all the answers

    What is the term for the cell membrane's ability to control what enters and leaves the cell?

    <p>Semi-permeability</p> Signup and view all the answers

    What is the purpose of the phosphate head groups in a phospholipid bilayer?

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

    What is the shape of the phospholipid bilayer?

    <p>A double layer</p> Signup and view all the answers

    What is the main reason why the cell membrane is able to form a bilayer structure?

    <p>The hydrophilic heads are attracted to water</p> Signup and view all the answers

    What is the function of the cell membrane in relation to the inside and outside of the cell?

    <p>To regulate what enters and leaves the cell</p> Signup and view all the answers

    Study Notes

    Cell Membrane Structure and Function

    • The cell membrane is a crucial structure that prevents cells from filling up with water or leaking substances into the environment.
    • It is semi-permeable, allowing certain substances to enter or leave the cell.

    Phospholipids: Building Blocks of the Cell Membrane

    • Phospholipids are the main components of the cell membrane.
    • They have three main components: phosphate head group, glycerol backbone, and two fatty acid tails.
    • The phosphate head group is hydrophilic (water-loving), while the fatty acid tails are hydrophobic (water-fearing).
    • This creates an amphipathic molecule with both hydrophilic and hydrophobic regions.

    Phospholipid Bilayer Formation

    • When phospholipids are placed in water, the hydrophilic phosphate head groups cluster together, while the hydrophobic fatty acid tails face inward.
    • This forms a unique structure called a phospholipid bilayer or lipid bilayer.

    Cell Membrane Structure in Real-Life Cells

    • In real cells, the phospholipid bilayer forms a sphere that surrounds the cell.
    • The hydrophilic phosphate head groups face outward, interacting with water, while the hydrophobic fatty acid tails face inward.

    Semi-Permeability of the Cell Membrane

    • The cell membrane is semi-permeable, allowing small, nonpolar molecules to pass through.
    • Examples of small, nonpolar molecules that can pass through the cell membrane include gases like O2 and CO2.
    • Small, polar molecules like water and ethanol can also pass through, but at a slower rate.
    • Large, nonpolar molecules like benzene can pass through, but slowly.
    • Large, polar molecules like glucose and charged molecules like ions and amino acids cannot pass through the cell membrane.

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    Description

    Learn about the importance of cell membranes in preventing water and substance leakage from cells. Discover how this outer layer of a cell works and its significance.

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