Biology Cell Membranes Quiz
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Questions and Answers

What are the components of a phospholipid?

  • One fatty acid, a triglyceride backbone, and a phosphate group
  • Two fatty acids, glycerol, a phosphate group, and an alcohol group (correct)
  • Two fatty acids, a starch molecule, and a nitrogen group
  • Glycerol, three fatty acids, and a phosphate group

    • What functions do membrane carbohydrates like glycolipids serve?

  • They are involved in cell recognition and adhesion. (correct)
  • They promote oxidation reactions in the cell membrane.
  • They contribute to lipid digestion in the cell.
  • They store energy for the cell.

    • Which type of glycolipid is found in plasma membranes and is important for blood type determination?

  • Neutral glycolipids
  • Galactolipids
  • Cerebrosides (correct)
  • Gangliosides

    • What is the primary component of the head group in glycolipids?

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

    How do glycolipids protect the plasma membrane in eukaryotic cells?

    <p>By shielding against low pH and degradative enzymes</p> Signup and view all the answers

    Which function is NOT attributed to glycolipids in eukaryotic cells?

    <p>Formation of the nuclear envelope</p> Signup and view all the answers

    What is one function of cholesterol in the cell membrane?

    <p>Regulates the permeability of cell membrane</p> Signup and view all the answers

    Which glycolipid acts as a receptor for cholera toxin?

    <p>Ganglioside GM1</p> Signup and view all the answers

    Which term best describes the arrangement of components in the fluid mosaic model?

    <p>A diverse mix with flexibility</p> Signup and view all the answers

    What role do glycoproteins play in cell membranes?

    <p>They assist in cell recognition and immune response.</p> Signup and view all the answers

    How do saturated hydrocarbon tails affect membrane fluidity?

    <p>They decrease fluidity by packing tightly together</p> Signup and view all the answers

    What is the significance of having unsaturated hydrocarbon tails in phospholipids?

    <p>They enhance membrane fluidity</p> Signup and view all the answers

    What happens to the lipid bilayer when heated?

    <p>It experiences a phase transition to fluid phase</p> Signup and view all the answers

    What does membrane fluidity primarily depend on?

    <p>The composition of the lipid tails</p> Signup and view all the answers

    What characteristic of membranes is associated with their asymmetry?

    <p>Different compositions on the inner and outer layers</p> Signup and view all the answers

    What is one consequence of cholesterol's presence in animal cell membranes?

    <p>Restrains phospholipid movement</p> Signup and view all the answers

    What is the primary function of the cell membrane?

    <p>To separate and protect the chemical components from the outside environment</p> Signup and view all the answers

    What is the chemical nature of the heads and tails of the phospholipids in the cell membrane?

    <p>Heads are hydrophilic while tails are hydrophobic</p> Signup and view all the answers

    Which types of molecules can pass through the cell membrane most easily?

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

    Which of the following statements about the structure of cell membranes is true?

    <p>Cell membranes have a lipid bilayer and various proteins</p> Signup and view all the answers

    What is the primary effect of Cholera toxin on intestinal cells?

    <p>Stimulates secretion of Chloride ions into the gut lumen.</p> Signup and view all the answers

    What type of glycosylation involves the attachment of glycans to the nitrogen of asparagine?

    <p>N-glycosylation</p> Signup and view all the answers

    What are amphipathic molecules?

    <p>Molecules that have both hydrophilic and hydrophobic properties</p> Signup and view all the answers

    Which of the following is NOT a function of glycoproteins?

    <p>Regulate blood pressure.</p> Signup and view all the answers

    What additional component is only found in the membranes of eukaryotic cells?

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

    What type of technique is freeze-fracture, and what does it achieve?

    <p>A preparation technique that splits membranes along the phospholipid bilayer</p> Signup and view all the answers

    What component characterizes the hydrophilic head of cholesterol?

    <p>Hydroxyl group responsible for its polarity.</p> Signup and view all the answers

    Which of the following molecules are unable to move through the cell membrane by themselves?

    <p>Ions and large hydrophilic molecules</p> Signup and view all the answers

    What is the role of lymphocytes in the immune system?

    <p>They recognize pathogens by detecting antigens.</p> Signup and view all the answers

    Which of the following statements about glycoproteins is accurate?

    <p>They are proteins with glycans attached to them.</p> Signup and view all the answers

    What distinguishes antigens from other proteins?

    <p>They always trigger an immune response when detected.</p> Signup and view all the answers

    How does the immune system ensure a wide variety of pathogen detection?

    <p>Using a unique set of antigen receptors on lymphocytes.</p> Signup and view all the answers

    Study Notes

    Cell Membrane

    • The cell membrane surrounds and protects all cells, separating their internal components from the outside environment.
    • It acts as a selective barrier, controlling the import and export of molecules thanks to transport proteins.
    • The membrane can move and expand.
    • It receives and processes information, facilitating cell communication.

    Cell Membrane Structure

    • The membrane is primarily composed of a lipid bilayer.
    • Phospholipids form the bilayer, consisting of hydrophilic (water-loving) heads and hydrophobic (water-fearing) tails.
    • Hydrophobic molecules pass easily through the membrane, while hydrophilic molecules do not.
    • Smaller molecules and larger hydrophobic molecules move across easily (e.g., O2, CO2, H2O).
    • Ions and hydrophilic molecules larger than water, as well as proteins, do not readily move without assistance.

    Membrane Lipids

    • Phospholipids: the most abundant, including saturated or unsaturated fatty acids, glycerol, a phosphate group, and an alcohol group (choline, ethanolamine, serine, or inositol).
    • Glycolipids: bound to carbohydrates.
    • Cholesterol: found only in eukaryotes.

    Properties of Lipids

    • All lipids have both hydrophilic and hydrophobic properties.
    • The behavior of lipids impacts the membrane's fluidity.

    Lipid Bilayer Characteristics

    • Properties: the lipid forms, fluidity, and asymmetry.
    • Types of lipids: membrane lipids.

    Membrane Proteins

    • Integral membrane proteins are embedded in the lipid bilayer.
    • Peripheral membrane proteins are loosely associated with the membrane surface.

    Carbohydrates and Cell Coat

    • Carbohydrates are attached to either lipids or proteins.
    • They are part of the cell membrane's glycocalyx.

    Freeze-Fracture

    • A technique to split cell membranes along the middle of the phospholipid bilayer, revealing internal membrane protein structure.

    Fluidity

    • The movement of lipids within the cell membrane.
    • Membrane flexibility influenced by lipid composition.

    Effect of Lipids on Fluidity

    • Saturated hydrocarbon tails pack tightly together, making the membrane less fluid.
    • Unsaturated hydrocarbon tails have kinks, preventing tight packing and enhancing fluidity.
    • Cholesterol embedded in animal cell membranes regulates fluidity and permeability.

    Effect of Temperature on Fluidity

    • Heating generally increases fluidity.
    • Membranes transition from a gel-like to a fluid-like state at different temperatures.

    Fluid Mosaic Model

    • Explains the structure of the cell membrane as a fluid mosaic, a combination of components, including phospholipids, proteins, cholesterol, and carbohydrates.

    Function of Cholesterol

    • Regulates cell membrane fluidity and permeability.

    Glycocalyx

    • Carbohydrates on the cell membrane's surface (either glycolipids, or glycoproteins), involved in cell-cell recognition, adhesion, and signaling.

    Glycolipids

    • Have a hydrophobic tail and a hydrophilic head (carbohydrate).
    • The hydroxyl group is crucial for causing the head's polarity.
    • Function in cell-cell recognition processes in eukaryotic cells and may provide protection against harsh conditions.

    Glycoproteins

    • Proteins with attached glycans (carbohydrate chains).
    • Commonly synthesized in endoplasmic reticulum (ER) post-translationally.
    • Involved in cell-cell recognition, immune responses, adhesion, and signaling.

    Function of Glycoproteins

    • Essential for immune system function, cell identification, and various bodily processes (including mucus creation for protection).

    Blood Type Glycolipids

    • An example of how glycolipids mediate cell interactions with the surrounding environment.

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    Related Documents

    B2212 Cell Physiology Chapter 2 Membrane Structure and Function Parts 1 and 2 PDF

    Description

    Test your knowledge on the components and functions of cell membranes, including phospholipids, glycolipids, and cholesterol. This quiz covers key concepts like membrane fluidity, the role of glycoproteins, and blood type determination related to glycolipids. Dive into the intricacies of cell membrane architecture and function!

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