Cytoskeleton and Cell Motility

Flashcards covering the key vocabulary terms related to the cytoskeleton.

Microtubules

Defines cell shape, acts as tracks for intracellular transport and cell division. It is the largest of the cytoskeleton components and is made of tubulin protein.

Intermediate filaments

Anchors organelles and reinforces the cell structure. It is intermediate in size and made of various fibrous proteins.

Microfilaments

Enables cells to change shape and move, involved in muscle contraction. It is the smallest of the cytoskeleton components and is made of actin protein.

Nucleation

Describes how a filament is formed de novo (from the beginning).

Polymerization

The process of monomers coming together to form filaments from an existing filament

Catastrophe

A dramatic shortening of the filament

Microtubule Functions

Forms mitotic spindle from the centrosome, moves transport vesicles, forms core of cilia and flagella

α-tubulin and β-tubulin

Globular monomers that make up microtubules.

Centrosome

Organelle that arranges microtubules for cell division

Centrosome matrix

Includes hundreds of ring-shaped structures formed from γ-tubulin and is a starting point for growth of microtubules

Microtubule Polymerization

Rapidly growing MT contain a GTP cap (GTP-bound heterodimers), due to faster rate of addition of α/β heterodimer than the rate of GTP hydrolysis to GDP which maintains the stability of the growing MT

Motor proteins

Use ATP to power cell’s mechanical work, move along microtubules (and actin filaments)

Kinesins

Motor proteins that move towards + end of microtubules

Dyneins

Motor proteins that move towards - end of microtubules

Intermediate Filament Function

Enable cells to withstand mechanical stress due to stretching, prevents tearing and make up nuclear lamina- meshwork of fibers that strengthens the nuclear envelope

Keratin

Type I/II intermediate filament, found in desmosomes & hair

Desmin

Type III intermediate filament, found in muscle sarcomere

Vimentin

Type III intermediate filament, connective tissue

Lamin

Type V intermediate filament, found in nuclear lamina

G actin

Actin are globular monomers

Microfilament Polymerization

Bind ATP, added more rapidly to (+) barbed end to form F-actin, involved in stabilizing (capping) and breakdown (severing) of the microfilament

Myosin I

Present in all cells, head binds to actin; tail carries cargo, walks to the + end of microfilaments

Myosin II

Involved in muscle contraction, 2 heads connect to microfilament at myosin-binding sites