Cytoskeleton and cellular architecture

Master’s-Level Cell Biology & Advanced Molecular Biology Notes 1. Definition Intermediate filaments (IFs) are rope-like cytoskeletal polymers approximately 10 nm in diameter, intermediate in size between actin filaments (~7 nm) and microtubules (~25 nm). Their primary function is to provide mechanical strength, structural integrity and resistance to deformation. Unlike actin and microtubules, intermediate filaments are generally non-polar and do not function as conventional tracks for motor proteins. Major functions 2. The Three Cytoskeletal Systems Feature Actin Intermediate filaments Microtubules Diameter ~7 nm ~10 nm ~25 nm Basic unit Actin IF protein α/β-tubulin Polarity Polar Non-polar Polar Main function Movement/force Mechanical strength Transport/organization Motor proteins MyosinRead More →

Master’s-Level Cell Biology & Advanced Molecular Biology Notes 1. Definition Microtubules are cylindrical, polarized cytoskeletal polymers composed primarily of α-tubulin and β-tubulin heterodimers. They are approximately 25 nm in diameter and represent the largest of the three major cytoskeletal filament systems. Microtubules are essential for: 2. Three Major Cytoskeletal Systems Feature Actin Intermediate filaments Microtubules Diameter ~7 nm ~10 nm ~25 nm Basic unit Actin IF protein α/β-tubulin Polarity Yes Generally no Yes Major motor Myosin None Kinesin, dynein Major nucleotide ATP None directly GTP Major dynamic behavior Treadmilling Relatively stable Dynamic instability Major roles Movement/contraction Mechanical strength Transport/mitosis 3. Basic Structure A microtubule isRead More →

Master’s-Level Cell Biology & Advanced Molecular Biology Notes 1. Definition The actin cytoskeleton is a dynamic network of actin filaments (microfilaments) distributed throughout the cytoplasm. It provides structural support and participates in: Unlike a static structural scaffold, the actin cytoskeleton is a highly dynamic, regulated system that continuously undergoes polymerization, depolymerization and remodeling. 2. Organization of the Cytoskeleton The cytoskeleton consists of three major filament systems: Component Approx. diameter Major function Actin filaments ~7 nm Cell shape, movement, contraction Intermediate filaments ~10 nm Mechanical strength Microtubules ~25 nm Intracellular transport, mitosis 3. Actin Structure Actin exists in two major forms: G-actin Globular actin A solubleRead More →