18-Cytoskeleton Flashcards
What is the cytoskeleton?
An intricate network of protein filaments that extends throughout the cytoplasm
What is the role of the cytoskelteton?
Strength and support to cell Allows cell shape changes Cell movement Cell contraction Wound healing Cell division Interaction with other cells Organisation of cell interior
Name the three types cytoskeletal filaments
Intermediate filaments
Microtubules
Actin filaments
What is the role of intermediate filaments?
Form a network of fibres inside that provide tensile strength
IFs allow cells to resist external forces such as stretching
What are the three main proteins of Intermediate filamets?
Keratin, vimentin and lamins
How do intermediate filaments provide a strong cytoskeleton?
the network of IFs desmosomal junctions become tensed and limit stretching in response to external forces.
What are the two different types of intermediate filaments?
Cytoplasmic and nuclaer
What are microtubules?
Stiff, hollow tubes made of the protein tubulin
Define microtubule expansion
Microtubules extend from an organising centre such as a centrosome, a spindle pole or the basal body of a cilium
Define microtubule contraction
If the growing microtubule doesn’t attach to something in the cell it will shrink
What is the centrosome?
Lies near the nucleus and has y-tubulin rings and each ring serves as the starting site for growth of a microtubule
What is the microutubules connection to the centromere?
MT are anchored at the centrosome close to the nucleus
What is dynamic instability?
Microtubules anchored in the centrosome can grow and shrink independently of each other
How is dynamic instability regulated?
Regulated by g-proteins
What are actin filaments?
AT are fibres involved in cell movement and shape
What is the role of actin filaments?
Involved in cell crawling, phagocytosis and cell division
How does actin regulate the cell cortex?
Actin polymerisation at the leading end of the cell pushes cell foward to form new actin cortex region
What are integrins?
Molecular hooks that allow cells to attach
How does actin regulate cell movement using ATP?
Actin chains grow by addition of actin monomer resulting in the hydrolysis of ATP. ADP remains trapped in the filament until the actin monomer dissociates from the filament
What are the importance of defects in cytoskeletal proteins in medicine?
IF are defective - EB and pemphigus
Nuclear lamina defective - progeria
