Cell Membrane & Vesicular Transport
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Questions and Answers

What is the main characteristic of the hydrocarbon chains in the cell membrane's structure?

  • They can be charged and hydrophilic.
  • They are nonpolar and hydrophobic. (correct)
  • They are polar and hydrophilic.
  • They are exclusively found on the membrane's outer layer.

    • What role does cholesterol play in the cell membrane?

  • It forms integral proteins within the membrane.
  • It acts as a charged head group.
  • It contributes to the asymmetry of oligosaccharide chains.
  • It provides structural stability and fluidity. (correct)

    • Which statement accurately describes integral proteins in the plasma membrane?

  • They span the membrane and may protrude from both sides. (correct)
  • They exclusively function on the outer membrane surface.
  • They are loosely associated with the membrane surfaces.
  • They are only found in the cytoplasm.

    • How do integrins function within the cell membrane?

    <p>They facilitate communication between the extracellular matrix and cytoplasm.</p> Signup and view all the answers

    What defines the trilaminar appearance of cellular membranes?

    <p>It occurs in all internal membranes and the plasma membrane.</p> Signup and view all the answers

    What is the primary function of organelle-specific membrane proteins?

    <p>They confer unique functions specific to certain organelles.</p> Signup and view all the answers

    What does the fluid mosaic model describe?

    <p>The dynamic arrangement of lipids and proteins in the membrane.</p> Signup and view all the answers

    How do peripheral proteins differ from integral proteins?

    <p>Peripheral proteins have a looser association with the membrane surfaces.</p> Signup and view all the answers

    What is the primary role of the glycocalyx in cells?

    <p>To aid in cell recognition and attachment.</p> Signup and view all the answers

    Which process is best described as 'cell eating'?

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

    What distinguishes receptor-mediated endocytosis from other types of endocytosis?

    <p>It involves specific receptors for macromolecules.</p> Signup and view all the answers

    Which of the following mechanisms is NOT a way molecules can cross the cell membrane?

    <p>Covalent bonding</p> Signup and view all the answers

    What is a characteristic feature of all cell membranes?

    <p>They exhibit asymmetry in protein and lipid distribution.</p> Signup and view all the answers

    What is the function of the phagosome in phagocytosis?

    <p>To enclose the engulfed material.</p> Signup and view all the answers

    Which transport mechanism is characterized by the bulk uptake of materials?

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

    How does pinocytosis differ from phagocytosis?

    <p>Pinocytosis involves fluid uptake while phagocytosis involves solid matter.</p> Signup and view all the answers

    What is the primary role of cholesterol in cell membranes?

    <p>To control the fluidity of cell membranes</p> Signup and view all the answers

    What is the appearance of sex chromatin in female cells?

    <p>It is tightly coiled and visible.</p> Signup and view all the answers

    How does the X chromosome in male cells differ from that in female cells?

    <p>The male X chromosome is uncoiled and not visible.</p> Signup and view all the answers

    How does cholesterol affect the permeability of cell membranes?

    <p>Decreases permeability to small water-soluble molecules</p> Signup and view all the answers

    In what way does cholesterol respond to cold temperatures?

    <p>Increases fluidity by separating fatty acid chains</p> Signup and view all the answers

    Where is the nucleolus primarily located?

    <p>Within the nucleus.</p> Signup and view all the answers

    What is synthesized in the nucleolus?

    <p>ribosomal subunits.</p> Signup and view all the answers

    What structural feature of cholesterol contributes to its function in membranes?

    <p>Amphipathic nature with hydrophilic and hydrophobic regions</p> Signup and view all the answers

    Why is cholesterol essential for certain membrane proteins?

    <p>It helps accommodate large proteins in thicker areas of the membrane</p> Signup and view all the answers

    What are the components of nucleoplasm?

    <p>A fluid portion and various particles.</p> Signup and view all the answers

    Which of the following describes cholesterol's distribution in the cell membrane?

    <p>Randomly distributed across the phospholipid bilayer</p> Signup and view all the answers

    Which phase of the cell cycle involves the synthesis of macromolecules for DNA duplication?

    <p>G1 phase.</p> Signup and view all the answers

    What occurs during the S phase of the cell cycle?

    <p>Replication of DNA.</p> Signup and view all the answers

    What effect would the lack of cholesterol have on cell membranes?

    <p>Membranes would be too fluid, not firm, and overly permeable</p> Signup and view all the answers

    Cholesterol molecules interact with which portion of the cell membrane?

    <p>Both the hydrophilic phosphate heads and the fatty acid region</p> Signup and view all the answers

    What is the functional significance of the association between heterochromatin and the nucleolus?

    <p>Its functional significance is not known.</p> Signup and view all the answers

    What is the primary function of the nuclear pores?

    <p>To allow the exchange of substances between the nucleus and cytoplasm</p> Signup and view all the answers

    Which of the following describes the structure of chromatin?

    <p>Contains DNA bound to basic proteins known as histones</p> Signup and view all the answers

    What is the size limit for ions and molecules to pass freely through the nuclear pore?

    <p>9 nm</p> Signup and view all the answers

    What is the term used to describe a gradual reduction in drug responsiveness due to repeated administration?

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

    What structure is the nucleus primarily made up of?

    <p>Nuclear envelope, chromatin, nucleolus, and nuclear matrix</p> Signup and view all the answers

    How are larger molecules transported through the nuclear pore?

    <p>Using active transport mediated by receptors and ATP</p> Signup and view all the answers

    Which term describes an acute, rapidly developed tolerance occurring after quick succession of doses?

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

    What type of RNA is synthesized and processed within the nucleus?

    <p>All types: ribosomal (rRNA), messenger (mRNA), and transfer (tRNA)</p> Signup and view all the answers

    What does the term 'hypersensitivity reaction' refer to?

    <p>Formation of antigen-antibody reactions</p> Signup and view all the answers

    Which part of the nucleus is primarily involved in assembling ribosomal RNA?

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

    What signifies the complete loss of effectiveness to antibiotics or anticancer agents?

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

    What connects the nuclear envelope to the endoplasmic reticulum?

    <p>Polyribosomes attached to the outer membrane</p> Signup and view all the answers

    Which term is used for the exaggerated response to a drug that can lead to symptoms like syncope?

    <p>Hyper-susceptibility</p> Signup and view all the answers

    What condition arises when withdrawal symptoms appear after the cessation of drug administration?

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

    What is the result of a genetic defect leading to abnormal drug reactions?

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

    What indicates a loss of therapeutic efficacy without complete drug ineffectiveness?

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

    Study Notes

    Cell Membrane & Vesicular Transport

    • Cell membranes are composed of phospholipids, cholesterol, proteins, and oligosaccharides
    • Phospholipids are amphipathic, with a hydrophilic head and hydrophobic tails
      • Glycerophospholipids (phosphoglycerides) have glycerol backbones
      • Sphingophospholipids have sphingosine backbones
    • Cholesterol controls membrane fluidity
    • Proteins in membranes include integral (spanning the bilayer), peripheral (loosely associated), and those specific to organelles
    • Carbohydrates are attached to lipids (glycolipids) or proteins (glycoproteins) on the outer surface, creating a glycocalyx
    • Membrane function includes transport and communication with the environment
    • Transport methods include passive (diffusion), active (pumps, cotransport), and bulk transport (endocytosis, exocytosis)
    • Endocytosis includes phagocytosis (cell eating), pinocytosis (cell drinking), and receptor-mediated endocytosis (specific uptake of molecules via receptors)

    Endocytosis

    • Mechanisms of endocytosis include:
      • Phagocytosis: engulfment of large particles
      • Pinocytosis: engulfment of fluid
      • Receptor-mediated endocytosis: selective uptake via receptors

    Lipid Structure & Functions in Biomembranes

    • Phospholipids are the primary lipids in cell membranes
    • There are two main types of phospholipids, phosphoglycerides and sphingophospholipids
    • Steroid lipid cholesterol is important for membrane fluidity and structural stability
    • Cholesterol helps control membrane fluidity
    • Cholesterol helps secure important proteins in the membrane

    Nucleus and phases of cell cycle

    • The nucleus contains the cell's genetic material (DNA) and the machinery for making RNA and proteins.
    • Chromatin is composed of DNA and proteins (specifically histones). Two types of chromatin exist: condensed heterochromatin and less condensed euchromatin.
    • Nucleolus is a region within the nucleus that produces ribosomes.
    • The nuclear envelope is a double membrane that surrounds the nucleus, containing nuclear pores that allow molecules to pass in and out.
    • Cell cycle phases include:
    • Interphase (G1, S, G2): growth, DNA replication, and preparation for mitosis
    • Mitosis: division of the nucleus (prophase, metaphase, anaphase, telophase)
    • Cytokinesis: division of the cytoplasm

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    Cell Membrane & Vesicular Transport PDF

    Description

    Test your understanding of cell membranes and their transport mechanisms. This quiz covers the composition, functions, and various transport methods such as diffusion, endocytosis, and exocytosis. Dive into the details of membrane structure and the roles of lipids, proteins, and carbohydrates.

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