Cytoskeleton Flashcards
1
Q
Cytoskeleton
A
a complex dynamic network of interlinking protein fibres extending throughout the cytoplasm that organises structures and activities in the cell
2
Q
Functions of cytoskeleton: tissue level
A
muscle movement/contraction
3
Q
Functions of cytoskeleton: cellular level
A
- mechanical support and protection
- maintains cell shape
- cell motility (flagella, cilia, lamellipodia)
- cell division
- cell adhesion
- phagocytosis
4
Q
Functions of cytoskeleton: sub cellular level
A
- anchors and organises organelles
- tensile strength
- stable cell polarity
- organelle and chromosome movement - intracellular vesicle transport
5
Q
Functions of cytoskeleton: general
A
- Strong
- Stable
- Dynamic
- Adaptable
6
Q
Components of cytoskeleton
A
- Microtubules
- Microfilaments (actin filaments)
- Intermediate filaments
7
Q
Principles of cytoskeleton dynamics
A
- each type of cytoskeletal filament (polymer) is constructed from smaller protein subunits (monomers)
- protofilaments associate laterally to provide thermal stability
- nucleation is the rate-limiting step in the formation of a cytoskeletal polymer
- subunits assemble head-to-tail to create polar filaments with two distinct ends that grow at different rates
— fast-growing end = plus end
— slow-growing end = minus end - filament treadmilling and dynamic instability are consequences of nucleotide hydrolysis
8
Q
Dynamic instability
A
Individual microtubules can alternate between a period of slow growth and a period of rapid shrinkage
9
Q
Motor proteins: structure
A
- globular head and fibrillar tail
- heavy chains and light chains - - head region:
— motor domain
— binds and hydrolyses ATP
— associates motor protein with its filament
tracks
— determines the identity of the track and
direction of movement along it - tail region:
–— determines the identity of the cargo
10
Q
Motor proteins: function
A
- movement of membrane-enclosed organelles
- cytoskeletal filament tension
- cytoskeletal filaments sliding against each other
