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Questions and Answers
What is one of the primary functions of microtubules?
What is one of the primary functions of microtubules?
- Translocation of organelles
- Formation of the contractile ring during mitosis
- Muscle contraction
- Maintenance of cell shape (correct)
Which statement accurately describes actin filaments?
Which statement accurately describes actin filaments?
- They are more rigid than microtubules.
- They primarily bind to keratins in epithelial cells.
- They are the largest component of the cytoskeletal system.
- They are 6 nm in diameter and are dynamic. (correct)
Which type of filament is found predominantly in muscle cells?
Which type of filament is found predominantly in muscle cells?
- Intermediate filaments
- Neurofilaments
- Actin filaments (correct)
- Microtubules
What role do intermediate filaments play in the cell?
What role do intermediate filaments play in the cell?
Which of the following is a characteristic of microtubules?
Which of the following is a characteristic of microtubules?
Which class of intermediate filaments is found in epithelial cells?
Which class of intermediate filaments is found in epithelial cells?
What distinguishes intermediate filaments from microtubules and actin filaments?
What distinguishes intermediate filaments from microtubules and actin filaments?
Which of the following is NOT a function of actin filaments?
Which of the following is NOT a function of actin filaments?
Which of the following is NOT a component of the cytoskeleton?
Which of the following is NOT a component of the cytoskeleton?
What is the diameter range of intermediate filaments?
What is the diameter range of intermediate filaments?
How many protofilaments form the circumference of each microtubule wall?
How many protofilaments form the circumference of each microtubule wall?
What is the primary function of microtubules in eukaryotic cells?
What is the primary function of microtubules in eukaryotic cells?
Which of the following best describes the structure of microtubules?
Which of the following best describes the structure of microtubules?
Which of the following processes is associated with the dynamic nature of microtubules?
Which of the following processes is associated with the dynamic nature of microtubules?
What role do the microtubules play in cellular movement?
What role do the microtubules play in cellular movement?
Which of the following best describes the function of the cytoskeleton?
Which of the following best describes the function of the cytoskeleton?
What is the primary role of intermediate filaments of keratins in skin epidermal cells?
What is the primary role of intermediate filaments of keratins in skin epidermal cells?
Which protein is considered an important vimentin-like protein found in muscle cells?
Which protein is considered an important vimentin-like protein found in muscle cells?
What is the function of lamins in the nuclear envelope?
What is the function of lamins in the nuclear envelope?
What is the size of a functional ribosome?
What is the size of a functional ribosome?
Where are ribosomal proteins synthesized before they are assembled into ribosomes?
Where are ribosomal proteins synthesized before they are assembled into ribosomes?
What distinguishes free polyribosomes from bound polyribosomes?
What distinguishes free polyribosomes from bound polyribosomes?
What role do neurofilament proteins play in cells?
What role do neurofilament proteins play in cells?
What property makes polyribosomes basophilic in stained preparations of cells?
What property makes polyribosomes basophilic in stained preparations of cells?
What is the main role of proteasomes in the cell?
What is the main role of proteasomes in the cell?
Which structure is responsible for recognizing ubiquitinated proteins?
Which structure is responsible for recognizing ubiquitinated proteins?
What is the composition of a centriole?
What is the composition of a centriole?
Which of the following is NOT a function of the proteasome?
Which of the following is NOT a function of the proteasome?
During which phase of the cell cycle does the centrosome duplicate?
During which phase of the cell cycle does the centrosome duplicate?
Which of the following statements about the proteasome's structure is true?
Which of the following statements about the proteasome's structure is true?
What type of proteins do proteasomes primarily deal with?
What type of proteins do proteasomes primarily deal with?
What happens to the centrosome during mitosis?
What happens to the centrosome during mitosis?
Study Notes
Non-Membranous Organelles
- Cytoskeleton: composed of microfilaments, intermediate filaments, and microtubules.
- Microfilaments: 6 nm in diameter, responsible for cell shape, locomotion, organelle movement, and muscle contraction.
- Microtubules: 25 nm in diameter, maintain cell shape, facilitate intracellular transport, and form structures like mitotic spindles, centrioles, basal bodies, and axoneme of cilia and flagella.
- Intermediate filaments: 8-10 nm in diameter, stable and diverse, important for cell structure and function depending on cell type.
- Keratins: found in epithelial cells, contribute to keratinization in skin.
- Vimentin: found in mesenchymal cells, and desmin in muscle cells, and GFAP in astrocytes, supporting cells of the central nervous system.
- Neurofilaments: found in neurons.
- Lamins: found in the nuclei of all cells, help maintain nuclear shape and participate in gene transcription.
- Ribosomes: 20 × 30 nm in size, essential for protein synthesis.
- Made of two subunits: small and large, bound to mRNA.
- Composed of rRNA and proteins.
- Exist as free or bound polyribosomes.
- Free polyribosomes: synthesize cytoplasmic proteins.
- Bound polyribosomes: associated with ER, synthesize membrane proteins, lysosomal enzymes, and secretory proteins.
- Proteasomes: cylindrical protein complexes that degrade denatured or nonfunctional proteins.
- Recognize proteins marked with ubiquitin.
- Unfold and degrade proteins in their core.
- Play a role in protein quality control and preventing cellular damage.
- Centrosomes: composed of two centrioles surrounded by pericentriolar matrix (PCM).
- Centrioles are cylindrical with nine microtubule triplets.
- Duplicate during DNA replication.
- Organize microtubules during mitosis, forming the mitotic spindle.
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Description
Test your knowledge on non-membranous organelles including cytoskeleton components such as microfilaments, microtubules, and intermediate filaments. Understand their structures, functions, and importance in cellular behavior. This quiz will challenge your understanding of these critical cellular components.
