lecture 5 Flashcards
what does cell motility mean
the abiltity for the cell to move and move its organelles
role of the cytoskeleton
The most obvious function of the cytoskeleton is to support the structure of the cell and maintain its shape. It also maintains the shape and function of the cell, as the cytoskeleton holds the organelles in place within the cell.
why do animal cells have cytoskeleton and plant cells don’t
because the plant cell has structure and support due to its cell wall, the animal cell doesn’t have this so the cytoskeleon instead provides support.
the cytoskeleton is dynamic, what does this mean
it can quickly be dismantled in one place then rebuilt in another area, changing the shape of the cell.
how does the cytoskeleton support motility of organelles
the kinesin walk, motor proteins walk and drag vesicles along microtubule high ways, along the cytoskeleton.
how does the cytoskeleton support vesicle production
The cytoskeleton also indents the plasma membrane to form the exocytosis vacuoles.
what are the three components of cytoskeleton
microtubules, microfilaments and intermediate filaments
describe the structure and the benefits of the microtubule structure
creates high amounts of compression resistance which thus helps to maintain cellular shape. Made of tubulin subnits, 25 nm diameter, these radiate out from organising centre, centrosome,
describe the structure and the benefits of the microfilaments structure
7nm diameter, two interwoven strands of actin(double twisted) . can be a linear strand or many can join together to create a 3d structure. the rope like structure helps the microfilaments to resist tension. actin also works with proteins like myosin in muscle cells to make muscles contract.
describe the structure and the benefits of the intermediate filaments structure
microfilaments are the most permanent component of the cytoskeleton, made of various proteins, keratin in hair, lamins in nucleus, neurofilaments in neurons, Supercoiled into “cables” 9-12 nm diameter. as its so strong its less dynamic, which makes the intermediate filament anchor organelles more permanently.
whats special about flagella and cilia
they are structures of a cell that are made from microtubules
what compensates for the lack of cell wall in an animal cell
the ECM
what is the ECM made of
The main ingredients for this ECM is Glycoproteins and other carbohydrate containing molecules that are secreted by cells. The most abundant glycoprotein in the ECM is collagen, which forms strong fibres outside the cell. Collagen is about 40% of all protein in the body.
what are collagen fibres embedded within
a woven network of proteoglycans.
whats special about the network of proteoglycans
These proteoglycans are secreted by cells and consist of core proteins with many carbohydrate chains attached to it.
Proteoglycan complexes form when hundreds of proteoglycans are attached together. Cells that are attached to the ECM are attached by glycoproteins, such as fibronectin.
how do the proteoglycans provide support to the cell
the proteoglycans hold water within them, which gives a cell shape and compression resistance. It also provides a way for the cell to anchor itself in place
what are integrins
Integrins connect ECM to cytoskeleton, transmembrane integral protein for example
what are fibronectins
Fibronectins are proteins that connect the cell to the ECM the dinosaurs.
what are the three cell junction types
tight, desmosome, gap
describe tight junctions
tight junctions connect the plasma membrane of two cells that are touching. Connecting them very tightly so no solutions can pass between the cells. The junction is not good at resisting tension, can be pulled apart with relative ease, this is why we pull muscles, as we forcefully separate muscle cells.
tight junctions are attached by what
Tight junctions are attached by microfilaments
describe desmosome junctions
this acts as an anchoring junction for two cells, preventing the cells from being pulled apart. These are made of intermediate filaments which is why they are strong
describe gap junction
these junctions have gaps that open up between the two cells, allowing rapid communication between cells. As the gap connects the cytoplasm of two cells, so ions can easily be passed between cells.
what role does the ECM do
helps cells attach to, and communicate with, nearby cells, also allows cells to move easily
why are integrins and fibronectins important
the connect the cell interior to the ECM allowing communication between the two.
fibronectin vs integrin
fibronectin connects plasma membrane to the ECM, (integrins) connect
the ECM to
cytoskeleton
b) Define an integrin and describe its function
Integrins are proteins that span the plasma membrane and connect the cytoskeleton to the ECM. Information about changes inside and outside the cell can be exchanged through a mechanical signalling pathway involving fibronectins, integrins and the cytoskeleton.
motor proteins walk along what
microtubules
what is the most abundant glycoprotein
The most abundant ECM
glycoprotein is collagen
collagen fibres are embedded in a what
a proteoglycan
complex matrix (green on figure)
v Proteoglycans are proteins
with extensive sugar
additions.
what funciton do proteogylcans have
Proteoglycans trap water
within the ECM
v Water resists compression
and thus helps retains
tissue shape.
what functions do glycoproteins have
collagen fibres have good tensile strength, resist tension
