Unit 1: The Cytoskeleton Flashcards
The cytoskeleton is an intricate, interconnected system of
protein filaments
The cytoskeleton is found only in what type of cell?
Eukaryotic
What is the purpose of the cytoskeleton?
To provide a framework of mechanical support to a cell allowing it to maintain its shape.
In cell division, the cytoskeleton is responsible for the movement of
chromosomes during meiosis and mitosis and the division of the cytoplasm during cytokinesis
What are the three parts of the cytoskeleton?
Actin filaments, Intermediate filaments and microtubules
What is the structure of actin filaments?
Two stranded helical chains of actin monomers
How are actin filaments arranged?
In linear bundles or networks
Networks of actin filaments help to do what?
Reinforce cell surface
What is the role of Actin filaments in cytokinesis?
Restructuring the cell surface
Actin filaments are also involved in ______ contraction
muscle
What is the structure of Intermediate filaments ?
Rope like fibres made up of fibrous proteins
What is the role of intermediate filaments?
Involved in the maintenance of the shape of cells or parts of cells including the nuclear envelope
An example of an intermediate filament is a ?
Lamin
Lamins are intermediate filaments that form a
meshwork called a nuclear lamina which reinforces the nuclear envelope
Microtubules are the largest _____ of the cytoskeleton
element
What is the structure of a microtubule?
Hollow cylinders composed of monomers of tubulin proteins
Alpha tubulin molecules join Beta tubulin molecules to form
tubulin heterodimers
Microtubules are dynamic structures that come form the
MTOC, microtubule organising centre
Animals have a single well defined MTOC called a
centrosome
A centrosome is
a microtubule organising centre
Microtubules are produced by a
MTOC which in animals is a centrosome
Microtubules form a network of intracellular railway tracks along which transport of
organelles occurs
Kinesin Motor Protein: Stage 1, Two kinase motorheads like a cherry with the organelle at the other end, one swings forward and attaches to a
microtubule
Kinesin Motor Protein: Stage 2, microtubule binding causes the release of
ADP
Kinesin Motor Protein: Stage 3, ATP is then rapidly introduced back to the moorhead and binds, this causes the other motorhead to
swing forward and attach to the microtubule track.
Microtubules form what important component of meiosis?
Spindle fibres
