Cell Structure and Organelles Quiz
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Questions and Answers

What is the primary role of free ribosomes in the cell?

  • To synthesize proteins for secretion outside the cell
  • To synthesize proteins used by the cell itself (correct)
  • To assist in the formation of the cytoskeleton
  • To form polysomes that transport proteins

    • Which structure is NOT considered a membranous organelle?

  • Lysosomes
  • Endoplasmic reticulum
  • Mitochondria
  • Ribosomes (correct)

    • What is the cytoplasmic matrix composed of?

  • Proteins and lipids
  • Soluble proteins, amino acids, and ions (correct)
  • Water and minerals
  • Nucleic acids and carbohydrates

    • Which of the following describes the structure of microtubules?

    <p>Straight hollow tubular structures formed of tubulin</p> Signup and view all the answers

    What characterizes attached ribosomes compared to free ribosomes?

    <p>Attached ribosomes bind to the outer surface of the endoplasmic reticulum</p> Signup and view all the answers

    Which of the following is a correct pairing of structure and function?

    <p>Ribosomes - protein synthesis</p> Signup and view all the answers

    Centriole and cilia are types of which cellular structure?

    <p>Cytoskeleton components</p> Signup and view all the answers

    What can be said about the cytoplasmic inclusions?

    <p>They include diverse substances such as glycogen and lipids</p> Signup and view all the answers

    Which type of filament is primarily responsible for muscle contraction?

    <p>Thick filaments</p> Signup and view all the answers

    What are the functions of intermediate filaments?

    <p>They provide structural support and have variable functions.</p> Signup and view all the answers

    Where is glycogen primarily stored in the body?

    <p>In muscle cells and liver cells</p> Signup and view all the answers

    Which structures are classified as inclusions within the cytoplasm?

    <p>Stored food, pigments, and crystals</p> Signup and view all the answers

    Which of the following describes exogenous pigments?

    <p>Pigments that are derived from external sources, like carotene</p> Signup and view all the answers

    What is the primary function of microtubules?

    <p>Facilitate intracellular transport and cell shape maintenance</p> Signup and view all the answers

    What structural feature distinguishes centrioles when viewed in cross-section?

    <p>They consist of 9 triplet microtubules surrounded by a fibrous matrix</p> Signup and view all the answers

    Which parts comprise a cilium?

    <p>Basal body, shaft, rootlets</p> Signup and view all the answers

    What unique structure is formed by microtubules during cell division?

    <p>Mitotic spindle</p> Signup and view all the answers

    Which statement accurately describes the appearance of centrioles using electron microscopy?

    <p>They are seen as two hollow cylindrical structures perpendicular to each other</p> Signup and view all the answers

    What is the role of the basal body in the structure of cilia?

    <p>Anchors the cilium to the cytoplasm</p> Signup and view all the answers

    Which method is commonly used to visualize microtubules?

    <p>Iron hematoxylin staining</p> Signup and view all the answers

    What type of organelle are microtubules classified as?

    <p>Non-membranous</p> Signup and view all the answers

    Study Notes

    Cell Structure

    • The cell is the basic unit of life, consisting of the nucleus and cytoplasm.
    • The cytoplasm contains the cytoplasmic matrix, cell organelles and inclusions.

    Cytoplasmic Matrix

    • This gel-like substance fills the space between organelles and inclusions.
    • It's a colloidal solution with soluble proteins, amino acids, carbohydrates, enzymes, minerals and ions.

    Cell Organelles

    • These are specialized structures within the cell responsible for specific functions.
    • They are categorized as either membranous or non-membranous.

    Non-Membranous Organelles

    • Ribosomes:

      • Composed of rRNA and protein, synthesized in the nucleolus.
      • Too small to be seen under a light microscope (LM) but appear as dense granules under an electron microscope (EM).
      • Can be free or attached to the endoplasmic reticulum (ER).
      • Free ribosomes synthesize proteins for cytoplasmic use.
      • Attached ribosomes synthesize proteins for export.

    • Cytoskeleton:

      • Provides structural support and helps maintain cell shape.
      • Facilitates intracellular transport.
      • Involved in cell division and movement of organelles.
      • Composed of microtubules and filaments.

    Microtubules

    • Straight, hollow tubes formed of tubulin.
    • Responsible for supporting the cell, intracellular transport, formation of the mitotic spindle, centrioles, cilia, and flagella.
    • Appear in bundles under special staining methods.

    Centrioles

    • Non-membranous organelles present near the nucleus in the centrosome.
    • Appear as two dots near the nucleus under LM.
    • Composed of 27 microtubules (9 triplets) in cross-section.
    • Function in cell division, formation of microtubules, and the basal body of cilia and flagella.

    Cilia

    • Motile, hair-like structures covered by the cell membrane, extending from the surface of epithelial cells.
    • Appear as striations under LM.
    • Composed of a basal body, a shaft (axoneme) and rootlets.
    • The basal body structure is identical to the centriole.
    • The shaft consists of 20 microtubules (9 doublets and 2 singlets).
    • The rootlets anchor the basal body and shaft to the cytoplasm.

    Filaments

    • Tiny thread-like structures responsible for elasticity and contractility of the cytoplasm.
    • Appear under silver stain (LM).
    • Classified as:
      • Microfilaments (thin filaments): Actin filaments found in muscle cells, microvilli, and the cell division ring.
      • Thick filaments: Myosin filaments present in muscle cells.
      • Intermediate filaments: Variable functions and distribution, including:
        • Desmin in muscle cells
        • Keratin in epithelial cells
        • Neurofilaments in nerve cells
        • Glial filaments in neuroglia cells

    Inclusions (Cytoplasmic Deposits)

    • Non-living, temporary components of the cytoplasm that are not essential for cell viability.
    • Examples include:
      • Stored food (glycogen and lipids)
      • Pigments (exogenous and endogenous)
      • Crystals

    Glycogen

    • The storage form of carbohydrates in the body.
    • Abundant in muscle and liver cells.
    • Not visible under H&E stain, but stained magenta with PAS.
    • Appear as electron-dense rosettes under EM.

    Lipids (Fat)

    • Primarily stored in adipocytes.
    • Not visible under H&E stain, but stained orange with Sudan III.
    • Appear as rounded, electron-dense droplets under EM.

    Pigments

    • Color-producing substances that can be exogenous or endogenous.

    Exogenous Pigments

    • Taken from outside the body.
    • Examples include:
      • Lipochromes (e.g., carotene)
      • Dust
      • Tattoo ink

    Endogenous Pigments

    • Produced within the body.
    • Examples include:
      • Hemoglobin
      • Melanin

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    Non-Membranous Organelles PDF

    Description

    Test your knowledge on cell structure and the functions of various organelles. This quiz covers the cytoplasmic matrix, ribosomes, and the classification of organelles. Dive deep into the fascinating world of cells and their components.

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