Lecture 14 - interactions between cells Flashcards
which tissue type has the most extracellular matrix
connective tissue
this provides strenght
what are tight junction function
seals neighbouring cells together
prevents leage between them
what are adherens junctions
joins actin bundles between cells
what is a desmosome
joins desmin intermediate filaments between cells
what is a gap junction
channels allowing small water soluble molecules between cells
what is a hemidesmosome
anchors intermediate filaments in a cell to basal lamina
name the plant gap junction equivalent
plasmodesmata
doesnt have anything else
what are tight junctions formed of
occludin and claudin proteins
how are epithelia ‘functionally polarised’
secretions from apical surface e.g. in airways, stomach, mammary gland
but also transport of nutrients into the blood
e.g. in intestines
what do adherin junctions and desmosomes use to link cells
cadherins
what does hemidesmosom use to link cell to basal lamina
integrins
what are cadherins
TM proteins that bind to each other between cells
what does cadherin need to interact with other cadherin
Ca2+
name of a contiuous band of adherin junctions
adhesion belt
what do cadherins link to to form the coniuous belt between cells
actin filaments
how could adherin junctions allow movement?
the actin filaments can be contractile
via myosin II
allowing the epithelial sheet to move
an example of the movement of epithelial cell sheets
neurulation in neural tube development
what type of wound closure associated with adhesion belt contractility
purse string wound closure
how can intermediate filaments help strengthen cells
protect against stretching
keratin filaments also linked via desmosomes
what can desmin mutations cause
muscular dystrophy
cardiac myopathy
where are desmosomes more abundant
in tissues under high stress eg heart muscle
or exposed epithelia
what do the integrins in the plasma memb bind to
between the laminin in basal lamina
and the IFs inside the cell
how do cadherins determine which cells interact
diff cells have diff cadherin
can only bind to indentical cadherin
e.g. epithelial cells = E cadherin
muscle cells = N-cadherin
how do cancer cells spread to other parts of the body (in terms of cadherin)
often no longer have cadherin that usually keep cell in right place
so it can just travel to diff parts of the body
what are carcinomas
cancer that starts in epithelial tissue (85%)
what forms the channel in gap junctions that allow movemnet between cells
connexons
what molecules typicallly pass through plasmodesmata
proteins
regulatory mRNAs
