Animal cells Flashcards
(41 cards)
How is an animal cells shape maintained
Held in cytoskeleton
What are the protein fibres
Microtubules
Intermediate filaments
Microfilaments
Microtubule function
Organelle movement
Form large structures outside of cells e.g. tubulin
Intermediate filament function
Mainly mechanical
Supports fragile tubulin e.g. keratin
Microfilament function
Provide support e.g. actin
What do motor proteins do
Change the position of things inside the cell e.g. kinesin
What do the proteins in the cell membrane do
Form links between cytoskeleton inside cell and extracellular matrix outside cell
Cytoskeleton functions
Organise organelles Maintain cell shape Anchorage to surfaces Cell movement (round body) Cell division (cytoplasm and nuclear material replicate and organise self) Allow contact and transmit signals
What happens if anchorage dependent cells are not anchored
Anchorage is dependent for their function
Without it they lose sense of direction
Anchored gives them direction and polarity
Directionality is phenotype feature
Cell pathway inside eukaryotes
Contractile microfilaments of cytoskeleton - lines of tension in cell
Energy transmitted through these lines, lets cell move across
Cell pathway in extracellular matrix
Extracellular matrix has fibronectin fibres
Each cell oriented to position of fibronectin fibres
Follow fibronectin trails
What are the benefits of cells sticking together
Form complex tissues and organs
Control material passage
Communicate, act in synchronised manner
What are the junctions that cells can attach together via
Adheren
Desmosomes
Tight junctions
Gap junctions
Where are there adheren junctions
In many epithelial cells
How does an adheren junction form and how is mechanical stress dealt with
Cadherin protein cross intracellular space, link to catenins
Catenins connect to actin filaments
Mechanical stress spread as anchored to actin filaments of cytoskeleton
How do substances pass between cells that are joined via adheren junctions
Substances pass between cells through intracellular spaces
Where are desmosome junctions
In most strong epithelia
How does a desmosome junction form and how is mechanical stress dealt with
Cadherins cross intracellular space, other proteins link cadherins to intermediate filaments
Attached to skeletal proteins inside cell
Anchored to intermediate filaments of cytoskeleton - even stress distribution
How do substances pass between cells that are joined via desmosome junctions
Substances pass freely between cells
Where are tight junctions
In intestinal epithelial cells and endothelial cells lining brain
How are tight junctions formed
Tightly packed row of protein ridges linking adjacent cells
Ensure adjacent cell membranes held together
How do substances pass between cells with tight junctions
Junction is impermeable due to tight packing of protein
What are tight junctions good for
Sealing body cavities/regions
Where are gap junctions formed
In e.g. nerve cells, heart muscle cells, pancreatic islet cells
