TRB PG Assistant - Structure and function of cytoskeleton Online Test (MCQ Quiz)

1. Which of the following is the primary function of the cytoskeleton?

A) Energy production within the cell B) Protein synthesis and packaging C) Maintaining cell shape and providing mechanical support D) DNA replication and transcription

2. What are the three main types of cytoskeletal filaments?

A) Actin filaments, intermediate filaments, and microtubules B) Microfilaments, tonofilaments, and neurofilaments C) Spindle fibers, contractile fibers, and flagella D) Keratin filaments, vimentin filaments, and glial filaments

3. Which cytoskeletal component is primarily composed of the protein actin?

A) Microtubules B) Intermediate filaments C) Actin filaments (microfilaments) D) Centrosomes

4. What is the diameter range of actin filaments (microfilaments)?

A) 2-4 nm B) 7-10 nm C) 10-12 nm D) 25 nm

5. Actin filaments are dynamic structures involved in various cellular processes. Which of the following is NOT a primary role of actin filaments?

A) Cell crawling (amoeboid movement) B) Muscle contraction C) Formation of the mitotic spindle D) Intracellular transport of vesicles

6. Which protein is the major component of microtubules?

A) Actin B) Tubulin C) Keratin D) Vimentin

7. What is the typical diameter of a microtubule?

A) 3 nm B) 7 nm C) 15 nm D) 25 nm

8. Microtubules play a crucial role in cell division by forming which structure?

A) The cleavage furrow B) The nuclear envelope C) The mitotic spindle D) The cell plate

9. Which cytoskeletal component is known for its tensile strength and ability to withstand mechanical stress?

A) Actin filaments B) Microtubules C) Intermediate filaments D) Centrioles

10. Intermediate filaments are a diverse group of proteins. Which of the following is NOT an example of an intermediate filament protein?

A) Keratin B) Vimentin C) Neurofilament D) Alpha-tubulin

11. What is the primary function of intermediate filaments in epithelial cells?

A) Facilitating cell movement B) Providing structural integrity and resisting shearing forces C) Transporting organelles D) Forming the contractile ring during cytokinesis

12. Which cytoskeletal component provides tracks for motor proteins like kinesin and dynein to transport organelles and vesicles?

A) Actin filaments B) Intermediate filaments C) Microtubules D) Desmosomes

13. The polymerization of actin monomers (G-actin) into filaments (F-actin) is known as:

A) Tubulin assembly B) Filament elongation C) Actin polymerization D) Intermediate filament formation

14. Which end of an actin filament typically shows faster polymerization (growth)?

A) The pointed end B) The barbed end C) Both ends at the same rate D) The plus end

15. What is the term for the dynamic process where actin filaments grow and shrink, often occurring at opposite ends?

A) Filament bundling B) Treadmilling C) Filament cross-linking D) Filament disassembly

16. Which protein is responsible for capping the plus end of actin filaments, preventing further polymerization?

A) Tropomyosin B) Cofilin C) CapZ D) Myosin

17. The protein tropomyosin is associated with actin filaments and plays a role in:

A) Nucleating microtubule formation B) Regulating muscle contraction by blocking myosin binding sites C) Providing tensile strength to intermediate filaments D) Linking intermediate filaments to the plasma membrane

18. Myosin is a motor protein that interacts with actin filaments. What is its primary function?

A) Stabilizing microtubule structure B) Generating force for muscle contraction and cell movement C) Forming the nuclear lamina D) Transporting vesicles along intermediate filaments

19. Which type of myosin is primarily involved in muscle contraction?

A) Myosin I B) Myosin II C) Myosin V D) Myosin VI

20. Microtubules are hollow cylinders formed from protofilaments, which are linear arrays of:

A) Actin monomers B) Tubulin heterodimers C) Intermediate filament proteins D) Vimentin subunits

21. What are the two main types of tubulin subunits that form a tubulin heterodimer?

A) Alpha-tubulin and Gamma-tubulin B) Beta-tubulin and Delta-tubulin C) Alpha-tubulin and Beta-tubulin D) Epsilon-tubulin and Zeta-tubulin

22. Microtubule polymerization is a polarized process. Which end typically grows faster?

A) The alpha-tubulin end (minus end) B) The beta-tubulin end (plus end) C) Both ends at the same rate D) The gamma-tubulin end

23. The dynamic instability of microtubules refers to their rapid switching between periods of growth and shrinkage. This is primarily driven by:

A) The binding of actin to microtubules B) The hydrolysis of GTP to GDP within tubulin subunits C) The action of myosin motor proteins D) The formation of intermediate filament networks

24. Which protein nucleates the formation of microtubules, often found in the centrosome?

A) Actin-related protein (ARP) B) Gamma-tubulin C) Myosin D) Keratin

25. The centrosome, a major microtubule-organizing center (MTOC) in animal cells, contains:

A) Actin filaments and myosin B) Intermediate filaments and desmin C) Centrioles and pericentriolar material D) Microvilli and stereocilia

26. Which motor protein moves towards the plus end of microtubules, typically carrying cargo away from the cell center?

A) Dynein B) Kinesin C) Myosin D) Actin

27. Which motor protein moves towards the minus end of microtubules, typically carrying cargo towards the cell center?

A) Kinesin B) Dynein C) Myosin D) Tubulin

28. Cilia and flagella are motile structures built upon a core arrangement of microtubules known as a:

A) Axoneme (9+2 arrangement) B) Mitotic spindle C) Contractile ring D) Actin bundle

29. Intermediate filaments are formed by the assembly of fibrous subunits into ropelike structures. What is a key characteristic of their assembly?

A) Requires GTP hydrolysis for polymerization B) Does not require ATP or GTP for assembly C) Involves rapid treadmilling D) Is primarily nucleated by gamma-tubulin

30. Which of the following is a characteristic of intermediate filament proteins?

A) They are globular proteins that polymerize into filaments B) They are highly conserved across different species C) They form a central, stable network within the cytoplasm D) They are primarily involved in rapid cell shape changes

31. Desmin is an intermediate filament protein found primarily in:

A) Nerve cells B) Muscle cells C) Epithelial cells D) Red blood cells

32. Neurofilaments are intermediate filaments that provide structural support to:

A) Muscle fibers B) Neuronal axons C) Epithelial tissues D) Red blood cells

33. The nuclear lamina, a meshwork lining the inner nuclear membrane, is composed of which type of cytoskeletal filament?

A) Actin filaments B) Microtubules C) Intermediate filaments (lamins) D) Myosin filaments

34. Which cellular structure is essential for maintaining the shape of the red blood cell and is composed of spectrin, an actin-binding protein?

A) Microtubules B) Intermediate filaments C) A spectrin-actin network D) Microvilli

35. Coordinated movement of cilia and flagella relies on the sliding of microtubule doublets past each other, powered by:

A) Myosin B) Kinesin C) Dynein arms D) Actin polymerization

36. The formation of the contractile ring during cytokinesis in animal cells is mediated by:

A) Microtubules B) Intermediate filaments C) Actin filaments and myosin D) Centrioles

37. Which component of the cytoskeleton is crucial for the formation of cell-cell junctions like desmosomes and hemidesmosomes?

A) Actin filaments B) Intermediate filaments C) Microtubules D) Microfilaments

38. The drug cytochalasin B inhibits actin polymerization. What effect would this have on a cell?

A) Disruption of the mitotic spindle B) Inhibition of cell crawling and cytokinesis C) Loss of nuclear structural integrity D) Impaired transport of vesicles along microtubules

39. The drug colchicine binds to tubulin and inhibits microtubule polymerization. What would be a likely effect on a cell?

A) Inhibition of muscle contraction B) Failure of the mitotic spindle to form, arresting cells in mitosis C) Loss of cell shape and mechanical strength D) Disruption of intracellular transport of organelles

40. Taxol (paclitaxel) stabilizes microtubules, preventing their depolymerization. How does this affect cell division?

A) It promotes the formation of the mitotic spindle B) It prevents the disassembly of the mitotic spindle, arresting cells in mitosis C) It facilitates chromosome segregation D) It enhances cell motility

41. Which cytoskeletal element is primarily responsible for forming the stress fibers observed in cultured fibroblasts?

A) Microtubules B) Intermediate filaments C) Actin filaments D) Centrosomes

42. The '9+2' arrangement of microtubules is characteristic of:

A) Centrioles B) Cilia and flagella C) The mitotic spindle D) Stress fibers

43. Which of the following is a function of actin filaments in non-muscle cells?

A) Providing mechanical strength against stretching B) Forming the nuclear lamina C) Mediating cytokinesis and cell migration D) Organizing the mitotic spindle

44. The protein spectrin is essential for maintaining the biconcave shape of red blood cells by linking actin filaments to:

A) Microtubules B) The plasma membrane C) Intermediate filaments D) The Golgi apparatus

45. Which of the following is a key role of microtubules in maintaining cell polarity?

A) Providing tracks for directed organelle movement B) Forming the contractile ring C) Reinforcing the cell membrane D) Generating force for cell crawling

46. Keratins are a major class of intermediate filaments found in:

A) Neurons B) Muscle cells C) Epithelial cells D) Red blood cells

47. The cellular process of phagocytosis involves the extension of pseudopods, which are driven by the dynamic assembly of:

A) Microtubules B) Intermediate filaments C) Actin filaments D) Centrioles

48. Which cytoskeletal component is primarily responsible for the formation and maintenance of the cell cortex, a layer just beneath the plasma membrane?

A) Microtubules B) Intermediate filaments C) Actin filaments D) The Golgi apparatus

49. The disruption of intermediate filaments can lead to increased susceptibility of cells to mechanical stress. This is because they provide:

A) Rapid movement capabilities B) Resistance to tensile forces C) Tracks for motor proteins D) Energy for cellular processes

50. The dynamic assembly and disassembly of the microtubule network is critical for:

A) Muscle contraction B) Cell shape maintenance C) Intracellular transport and chromosome segregation D) Providing tensile strength

Structure and function of cytoskeleton - Online Test

Test Results