Podcast
Questions and Answers
What is the diameter of microtubules in a cell?
What is the diameter of microtubules in a cell?
Which type of filament is exclusively found in animal cells?
Which type of filament is exclusively found in animal cells?
What are the two primary components of tubulin?
What are the two primary components of tubulin?
What function does the cytoskeleton serve in cellular movement?
What function does the cytoskeleton serve in cellular movement?
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What is the primary microtubule organizing center in a cell?
What is the primary microtubule organizing center in a cell?
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How many protofilaments typically form a single microtubule in mammalian cells?
How many protofilaments typically form a single microtubule in mammalian cells?
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Which of the following is a characteristic of microfilaments?
Which of the following is a characteristic of microfilaments?
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What role do centrioles play in the organization of microtubules?
What role do centrioles play in the organization of microtubules?
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What is the primary role of the cytoskeleton in a cell?
What is the primary role of the cytoskeleton in a cell?
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Which filamentous structure is responsible for rapidly growing and shrinking?
Which filamentous structure is responsible for rapidly growing and shrinking?
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How many different protein subunits compose intermediate filaments in humans?
How many different protein subunits compose intermediate filaments in humans?
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What structural feature characterizes microtubules?
What structural feature characterizes microtubules?
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What is the composition of centrioles?
What is the composition of centrioles?
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What diameter do microfilaments share?
What diameter do microfilaments share?
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What is the function of microtubule organizing centers (MTOCs) in cells?
What is the function of microtubule organizing centers (MTOCs) in cells?
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What type of filaments are associated with muscle cells?
What type of filaments are associated with muscle cells?
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What happens to the nuclear membrane during prophase?
What happens to the nuclear membrane during prophase?
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Which role do kinetochore microtubules play in anaphase?
Which role do kinetochore microtubules play in anaphase?
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During which phase do chromosomes migrate to the equatorial plane?
During which phase do chromosomes migrate to the equatorial plane?
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What key process is observed during anaphase?
What key process is observed during anaphase?
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What is the function of the mitotic spindle checkpoint?
What is the function of the mitotic spindle checkpoint?
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Which complexes contribute to the exit from metaphase?
Which complexes contribute to the exit from metaphase?
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What characterizes telophase in the cell cycle?
What characterizes telophase in the cell cycle?
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Which type of microtubule is responsible for positioning the spindle apparatus during mitosis?
Which type of microtubule is responsible for positioning the spindle apparatus during mitosis?
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What is the primary purpose of somatic cell division in eukaryotes?
What is the primary purpose of somatic cell division in eukaryotes?
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Which phase directly follows karyokinesis during mitosis?
Which phase directly follows karyokinesis during mitosis?
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Which of the following accurately describes cyclin-dependent kinases (CDKs)?
Which of the following accurately describes cyclin-dependent kinases (CDKs)?
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What occurs during the prophase phase of mitosis?
What occurs during the prophase phase of mitosis?
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Which kinase is primarily responsible for phosphorylating H1 histone during prophase?
Which kinase is primarily responsible for phosphorylating H1 histone during prophase?
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Which phase of mitosis is characterized as the separation phase?
Which phase of mitosis is characterized as the separation phase?
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What role do Polo-like kinases and Aurora kinases play in mitosis?
What role do Polo-like kinases and Aurora kinases play in mitosis?
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How are sister chromatids held together during prophase?
How are sister chromatids held together during prophase?
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Study Notes
Cell Division - Cytoskeleton
- The cytoskeleton is composed of three filamentous structures: microtubules, microfilaments (actin filaments), and intermediate filaments.
Cytoskeleton - Functions
- Maintains cell shape and changes shape during movement (e.g., cell division, organelle migration, cell migration).
- Positions organelles.
- Resists deformation.
- Transports intracellular cargo (e.g., vesicles) and assists in the transport of communication signals between cells.
Microtubules
- The largest type of filament, composed of tubulin protein.
- Diameter is approximately 25 nanometers.
- Tubulin is composed of α-tubulin and β-tubulin subunits assembled into linear protofilaments.
- Microtubules can rapidly grow or shrink in size through polymerization and depolymerization, respectively.
- The size depends on the number of tubulin molecules they contain.
- A single microtubule contains 10 to 15 protofilaments (13 in mammalian cells).
- They wind together to form a 24 nm wide hollow cylinder.
Centrosome
- In cells, the minus ends of microtubules are anchored in structures called microtubule-organizing centers (MTOCs).
- The primary MTOC in a cell is the centrosome.
- The centrosome consists of two centrioles.
- The centrosome is duplicated during the S phase of the cell cycle.
Centrioles
- Occur as paired cylindrical organelles together with pericentriolar material (PCM) containing more than 100 different proteins.
- Constructed of microtubules.
- Organize the PCM to produce microtubules, including mitotic spindle fibers.
Intermediate Filaments
- Composed of different protein subunits (~70 in humans).
- Diameter is approximately 10 nanometers.
- Found only in animal cells.
- Associated with specific cell types: neurofilaments in neurons, desmin filaments in muscle cells, and keratins in epithelial cells.
Microfilaments
- The smallest type of filament composed of the contractile protein actin.
- Diameter is approximately 8 nanometers.
- Particularly prevalent in muscle cells.
Motor Proteins
- Use energy derived from ATP hydrolysis to generate movement and force.
- Involved in cell movement:
- Kinesin moves along microtubules to pull organelles towards the cell membrane.
- Dynein pulls cellular components inward (toward the nucleus) and works to slide microtubules.
- Myosin interacts with actin to perform muscle contractions, and is involved in cytokinesis, endocytosis, and exocytosis.
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Description
This quiz covers the composition and functions of the cytoskeleton, including its three main filamentous structures: microtubules, microfilaments, and intermediate filaments. Explore how these components maintain cell shape, assist in cell movement, and facilitate intracellular transport.
