Cytoskeleton & Cell Inclusions Quiz

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Questions and Answers

Which type of intermediate filament is found in muscle cells?

Desmin (correct)

Lamins

Vimentin

Neurofilaments

What is the diameter of intermediate filaments?

10 nm (correct)

100 nm

7 nm

25 nm

Which protein makes up the triplet arrangement in each centriole?

Actin

Vimentin

Tubulin (correct)

Keratin

Which of the following is NOT a function of the centrosome?

Cytoplasmic streaming Signup and view all the answers

Which intermediate filament is associated primarily with epithelial cells?

Keratin Signup and view all the answers

What characterizes the structural composition of microtubules?

9 triplets of microtubules Signup and view all the answers

In which type of cells is vimentin primarily found?

Mesenchymal cells Signup and view all the answers

What is the primary function of glycogen in cells?

Source of energy Signup and view all the answers

What color does periodic-acid Schiff stain appear?

Magenta red Signup and view all the answers

In which type of cells is hemosiderin primarily found?

Phagocytic cells Signup and view all the answers

What is the primary function of lipids in the body?

Synthesis of membranes and steroid hormones Signup and view all the answers

Which of the following describes the appearance of lipids when stained with osmium tetroxide?

Black Signup and view all the answers

What best describes the primary characteristic of intermediate filaments?

Permanent structures that provide resistance to tension Signup and view all the answers

What is the appearance of pigments like lipofuscin in cells?

Yellow-brown pigment Signup and view all the answers

What type of granules are observed in protein-synthesizing cells like salivary glands?

Eosinophilic zymogen granules Signup and view all the answers

Which of the following is NOT an endogenous pigment?

Tattoo ink Signup and view all the answers

What is the primary function of microfilaments in muscle cells?

Muscle contraction associated with myosin Signup and view all the answers

Which of the following describes the structural protein that forms microtubules?

Globular protein dimer called tubulin Signup and view all the answers

What is the main role of intermediate filaments in the cytoskeleton?

Provide stability and structural support Signup and view all the answers

Which characteristic distinguishes microtubules from microfilaments?

Microtubules are dynamic structures Signup and view all the answers

Which proteins are involved in the movement of vesicles along microtubules?

Kinesin and dynein Signup and view all the answers

What is a function associated with microfilaments during cell division?

Formation of the contractile ring Signup and view all the answers

How are microfilaments visualized in light microscopy?

Through immunohistochemical staining Signup and view all the answers

What process is facilitated by microtubules in cellular function?

Transport of organelles and vesicles Signup and view all the answers

Study Notes

Cytoskeleton

Comprised of structural proteins, forming a non-membranous network in cells.
Three primary types: microfilaments, microtubules, and intermediate filaments.

Microfilaments

Diameter: 7 nm, visualized via immunohistochemical staining.
Composed of G-actin monomers that polymerize into F-actin, arranged in a double helix.
Functions include:
- Cell motility (migration, cytoplasmic streaming, cytokinesis, muscle contraction).
- Structural support (maintenance of cell shape, formation of microvilli core).

Microtubules

Diameter: 25 nm, identifiable through immunohistochemical staining.
Made of tubulin dimers (alpha and beta subunits) forming protofilaments, with 13 protofilaments composing a microtubule.
Functions include:
- Transport of vesicles and organelles.
- Formation of mitotic spindles, centrioles, cilia, and flagella.
- Key players in cellular movement with motor proteins, kinesin and dynein, using ATP for transport.

Intermediate Filaments

Diameter: 10 nm, visualized using immunohistochemical methods.
Comprised of fibrous proteins, exhibiting a woven rope-like structure.
The most stable cytoskeletal components, contributing primarily to structural integrity.
Classified into cytoplasmic (e.g., keratin, vimentin, desmin) and nuclear types (lamins).
Useful in cancer diagnostics through immunohistochemical staining, revealing tissue origin.

Centrosome

A non-membranous organelle consisting of two centrioles oriented perpendicularly.
Each centriole consists of 9 triplets of microtubules (totaling 27 microtubules).
Functions include:
- Serving as a microtubule-organizing center.
- Facilitating formation of the mitotic spindle and cilia/flagella.

Cell Inclusions

Defined as stored substances within cells, including food reserves and pigments.

Glycogen

A carbohydrate storage form, primarily found in liver and muscle cells.
Functions as a source of energy, appearing as dense granules in EM.

Lipids

Serve as energy sources and building blocks for membranes and hormones.
Stored mainly in adipocytes, visualized differently under various staining techniques.

Proteins

Present in protein-synthesizing cells (e.g., salivary glands, pancreas).
Visible as eosinophilic zymogen granules under LM and homogenous electron-dense granules in EM.

Pigments

Endogenous Pigments:
- Hemoglobin in RBCs, hemosiderin in liver/spleen, melanin, and lipofuscin.
Exogenous Pigments:
- Pigments introduced by tattooing, and accumulation of dust/smoke in the lungs.

Key Takeaway on Intermediate Filaments

They are permanent structures that provide resistance against tension exerted on cells, contributing to overall cellular stability.

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Description

Test your knowledge on the cytoskeleton and cell inclusions with this quiz. Explore different types, structures, and functions of cytoskeletal components such as microfilaments, microtubules, and intermediate filaments, along with the role of centrosomes. Perfect for biology students and anyone interested in cell biology!