Cytoskeleton Flashcards
What is the cytoskeleton and the three filamentous structures that compose it
What are the functions of cytoskeletal components
What are intermediate filaments
What are the 4 major classes of intermediate filaments
Describe keratin containing intermediate filaments
Describe neurofilaments
Explain IF assembly and disassembly
What are IF linker proteins
Describe actin filament structure
Explain actin filament assembly and disassembly
Actin filaments can grow by the addition of monomers at either end, but their rate of growth is faster at the plus end (10 times) than at the minus end.
▪ Before it is incorporated into a filament, an actin monomer binds an ATP molecule, and therefore, Actin is an ATPase.
▪ The initial nucleation event in filament formation occurs slowly in vitro, whereas the subsequent stage of filament elongation occurs much more rapidly.
▪ The ATP associated with the actin monomer is hydrolyzed to ADP at some time after it is incorporated into the end of a growing filament.
What is the function of actin filament assembly and disassembly
By controlling the assembly/disassembly, the cell can rapidly reorganize its actin
cytoskeleton when and where is needed for dynamic processes such as:
✓cell locomotion
✓changes in cell shape
✓phagocytosis
✓Cytokinesis
▪ Assembly/disassembly rate can be influenced by several actin-binding proteins
What are acting binding proteins
Describe cell motility (crawling)
What are myosins
Describe myosin I
Describe myosin II
How does F actin and Myosin II interact
Describe muscle organization
Explain muscle contraction of the sliding filament model
What are microtubules
✓ Determine cell shape
✓ Position membrane-enclosed organelles within the cell
✓ Provide tracks for vesicles and organelle transport within a cell
✓Involved in mitotic spindles formation and cell division
Describe the structure and composition of microtubules
What are centrosomes
What are the dynamic properties of microtubules
Explain microtubule assembly (growth) and disassembly (shrinking)
What are the microtubule-associated proteins
Describe microtubule function in intracellular motility
How do motor proteins traverse the microtubular cytoskeleton
▪ Motor proteins convert chemical energy (stored in ATP) into mechanical energy, to
generate force to, for example, move cellular cargo.
▪ Microtubules and actin filaments serve as tracks for a variety of motor proteins that
generate forces required to efficiently move objects within a cell.
Motor proteins:
▪ Can be grouped into three broad superfamilies:
* Kinesin and Dynein which move along microtubules
* Myosin which moves along the actin filaments
▪ Move unidirectionally along their cytoskeletal track in a stepwise manner from one
binding site to the next
How do microtubules provide support and organization
Describe kinesin-mediated organelle transport
Describe basal bodies
Describe the structure of eukaryotic cilia and flagella
▪ cilia and flagella share a similar internal
structure (Axoneme).
▪ Axoneme:
* Is the core of the cilium/flagellum
* Contains an array of microtubules that runs
longitudinally through the entire organelle
* The axoneme of a motile cilium or flagellum
consists of nine peripheral doublet
microtubules surrounding a central pair of
single microtubules (known as the 9 + 2
array)
Explain the mechanism of ciliary and flagellar locomotion
▪ Because of the multiple links that hold the
adjacent microtubule doublets together, the
sliding force between adjacent microtubules is
converted to a bending motion
▪ Other ciliary components control dynein
activity leading to the complex wave seen in
cilia and flagella
