Week 4: Cytoskeleton And Cell Movement Flashcards
What is the cytoskeleton?
A system of protein filaments that provides spatial and mechanical functions to cells
The cytoskeleton is essential for various cellular processes.
What are the three main types of filaments that form the cytoskeleton?
- Actin filaments
- Microtubules
- Intermediate filaments
What are the functions of the cytoskeleton?
- Pulls chromosomes apart at mitosis
- Splits dividing cells
- Drives intracellular traffic of organelles
- Supports the plasma membrane
- Enables cell movement
- Provides framework for muscle contraction
- Allows neurons to extend axons and dendrites
What is the diameter of actin filaments?
5 - 9 nm
What structures do actin filaments form?
- Stable structures for muscle contraction
- Transient structures for cell movement
What are microtubules composed of?
Subunits of tubulin: α and β heterodimer
Microtubules are long hollow cylinders.
What is the diameter of microtubules?
25 nm
What role do intermediate filaments play in the cell?
Provide mechanical strength and resistance to shear stress
They form a mesh that lines the inner surface of the nuclear membrane.
Name some types of intermediate filaments.
- Lamins
- Vimentins
- Desmin
- Keratin
- Neurofilaments
What is the function of accessory proteins in the cytoskeleton?
Regulate the number, length, and geometry of filaments
What is the role of the ARP 2/3 complex?
Allows elongation of actin filaments in one direction and can form web-like structures
What does the centrosome do in microtubule nucleation?
Acts as the microtubule-organising centre (MTOC) located near the nucleus
What is the significance of tubulin as a GTPase?
Hydrolyzes GTP to GDP, affecting microtubule stability
Tubulin-GTP is stable, while tubulin-GDP is unstable.
What are the three types of higher order actin structures?
- Contractile bundle
- Gel-like network
- Tight parallel bundle
What is the function of myosins in the cell?
Act as motors that walk along actin filaments carrying out cellular functions
