Chapter 13: Cytoskeletal Systems

These flashcards cover key vocabulary and definitions related to cytoskeletal systems, focusing on microtubules, microfilaments, intermediate filaments, and their functions.

Cytoskeleton

A network of interconnected filaments and tubules extending through the cytosol, playing roles in cell movement and division.

Microtubules

The largest structural elements of the cytoskeleton, composed of tubulin subunits, involved in cell movement and division.

Microfilaments

The smallest filaments of the cytoskeleton, made of actin subunits, known for their role in muscle contraction and cell migration.

Intermediate Filaments

Filaments within the cytoskeleton that are 8-12 nm in diameter, variable in composition, and provide structural support.

Tubulin Heterodimers

The protein building blocks of microtubules, consisting of one alpha-tubulin and one beta-tubulin.

GTP Cap

A structure at the plus end of a microtubule that stabilizes its growth and prevents subunit removal.

Dynamic Instability

A model describing the rapid polymerization and depolymerization of microtubules, characterized by periods of growth and shrinkage.

Actin

A highly conserved, abundant protein in eukaryotic cells that forms microfilaments, involved in muscle contraction and cell movement.

Microtubule-Organizing Center (MTOC)

Structure that nucleates and anchors microtubules, often associated with centrosomes in animal cells.

Rho GTPases

A family of monomeric G proteins that regulate the assembly of actin-based structures in response to various signals.

Colchicine

A chemical agent that binds to β-tubulin, inhibiting microtubule assembly and promoting disassembly.

Actin-Binding Proteins

Proteins that regulate the polymerization, length, and organization of actin filaments.

Microvilli

Small projections on the surface of intestinal cells that increase surface area, composed of actin filaments.

Spectrin

A protein that connects actin filaments to the plasma membrane, providing cell structure.

Chemical Agents

Substances that can perturb cytoskeletal functions, affecting the stability and assembly of microtubules and microfilaments.

What are the main characteristics of Intermediate Filaments?

Intermediate filaments are rope-like, have a diameter of 8-12 nm, are highly stable, lack dynamic instability, and are tissue-specific in their protein composition.

What are Lamin Intermediate Filaments?

Class V intermediate filaments that form a meshwork beneath the inner nuclear membrane, providing structural support to the nucleus.

What is Keratin?

A type of intermediate filament, primarily found in epithelial cells, providing mechanical strength to tissues like skin, hair, and nails.

What is the function of Kinesin?

A motor protein that moves along microtubules toward the plus end, transporting cargo like vesicles and organelles.

What is the function of Dynein?

A motor protein that moves along microtubules toward the minus end, involved in vesicle transport, and critical for ciliary and flagellar movement.

What is the function of Myosin?

A motor protein that interacts with actin (microfilaments), responsible for muscle contraction, cell division (cytokinesis), and various forms of cell movement.

Cilia and Flagella structure

Hair-like appendages on cell surfaces, composed of a 9+2 array of microtubules, responsible for cell motility or moving fluids.

Mitotic Spindle

A dynamic structure of microtubules formed during cell division, responsible for the segregation of chromosomes into daughter cells.

What are Lamellipodia and Filopodia?

Lamellipodia are broad, sheet-like protrusions of the cell membrane, driven by actin polymerization, enabling cell crawling. Filopodia are thin, finger-like projections containing parallel bundles of actin filaments, involved in cellular exploration and sensing.

Cell Cortex

A meshwork of actin filaments and associated proteins located beneath the plasma membrane, providing mechanical support, involved in cell shape changes and movement.