Microfilaments: Structure, Function, and Examples in Cells

📚 Quick Study Guide

• 🧬 Microfilaments are the thinnest filaments of the cytoskeleton, primarily composed of the protein actin.
• 🔍 They are about 7 nm in diameter.
• 💡 Microfilaments are highly dynamic, constantly polymerizing and depolymerizing.
• 💪 Functions include cell movement, muscle contraction, cell shape maintenance, and cytokinesis.
• 🏃 Actin monomers assemble into helical filaments.
• 🌱 Examples: Muscle cells (muscle contraction), epithelial cells (cell junctions), and migrating cells (lamellipodia formation).
• 🧪 Drugs like cytochalasin can disrupt microfilament function.

🧪 Practice Quiz

1. Which protein is the primary component of microfilaments?
   1. Actin
   2. Tubulin
   3. Keratin
   4. Collagen


2. What is the approximate diameter of a microfilament?
   1. 25 nm
   2. 10 nm
   3. 7 nm
   4. 15 nm


3. Which of the following is a function of microfilaments?
   1. Cell shape maintenance
   2. Chromosome segregation
   3. Protein synthesis
   4. Energy production


4. What process describes the assembly of actin monomers into filaments?
   1. Glycosylation
   2. Polymerization
   3. Phosphorylation
   4. Hydrolysis


5. In muscle cells, microfilaments are crucial for:
   1. Cell division
   2. Muscle contraction
   3. Nutrient transport
   4. Waste removal


6. Which cellular structure relies on microfilaments for its formation during cell migration?
   1. Cilia
   2. Flagella
   3. Lamellipodia
   4. Ribosomes


7. What effect does cytochalasin have on microfilaments?
   1. Stabilizes them
   2. Disrupts their function
   3. Enhances their polymerization
   4. Has no effect