Cell Cytoskeleton Components: Actin, Intermediate Filaments, Microtubules

What are the three main components of the cytoskeleton?

Actin filaments, intermediate filaments, and microtubules.

What is the primary function of the cytoskeleton?

It gives a cell its shape, organizes internal components, and allows movement.

What are intermediate filaments made of?

Cytoskeleton proteins that provide great tensile strength.

Where are intermediate filaments found in the cell?

In the cytoplasm, surrounding the nucleus, and extending to the cell periphery.

What is the role of intermediate filaments in the nucleus?

They form the nuclear lamina, which strengthens the nuclear envelope.

What are the four classes of intermediate filaments?

Keratin filaments, vimentin, neurofilaments, and nuclear lamin.

What is the structure of microtubules?

Hollow tubes made of tubulin proteins that can rapidly assemble and disassemble.

What is the function of microtubules in the cell?

They create tracks for the transport of vesicles and other components, and are important for cell division.

What is the centrosome?

A central structure in animal cells that organizes microtubules.

What is dynamic instability in microtubules?

The rapid growth and shrinkage of microtubules driven by GTP hydrolysis.

What are MAPs (microtubule-associated proteins)?

Accessory proteins that stabilize microtubules against disassembly.

What are motor proteins and their function?

Proteins that use ATP energy to transport cargo along microtubules or actin filaments.

What are the two types of motor proteins associated with microtubules?

Kinesins (move toward the + end) and dyneins (move toward the - end).

What are actin filaments made of?

Actin monomers that form a stiff and stable structure.

What is the significance of actin filament polarity?

It allows for directional growth and stability of the filament.

What is 'treadmilling' in actin filaments?

The process where actin monomers are added at the + end and lost at the - end, maintaining filament length.

What role do actin-binding proteins play?

They regulate the polymerization and properties of actin filaments.

What is the cell cortex?

A network of actin filaments linked by actin-binding proteins that supports the plasma membrane.

How do cells crawl using actin filaments?

By extending protrusions at the leading edge and anchoring them to the surface.

What are lamellipodia and filopodia?

Lamellipodia are broad extensions of the leading edge, while filopodia are thin, actin-rich protrusions.

What is the role of ATP in actin filament dynamics?

ATP hydrolysis regulates the polymerization and stability of actin filaments.

What is the function of thymosin and profilin in actin dynamics?

They limit actin polymerization by binding to actin monomers.

What is the role of formins in actin polymerization?

Formins promote the assembly of actin filaments.

What is the significance of the nuclear lamina?

It provides structural support to the nucleus and is formed by intermediate filaments.

How do microtubules contribute to neuronal function?

They provide tracks for vesicle transport along axons.

What is the role of gamma-tubulin in microtubule formation?

It serves as a starting point for the growth of microtubules at the centrosome.