Systems biology of the cell Flashcards
(20 cards)
what do cells need to become in order to communicate?
polar
differential adhesion hypothesis
Steinberg (1963) proposed:
cell sorting driven by differential adhesion between cell types in a tissue
cells that adhere more with one another, form a tissue with a higher surface tension
tissues will separate based on their surface tensions
how can the surface tension of a cell be measured?
by ‘squeezing it’, measuring the epithelium
how can we test the hypothesis of differential adhesion?
making an in silico cell, this uses a computer to model a cell
name the cell surface mechanics
area conservation = γa(a-A)2 (squared)
adhesion-driven tension = Jp
cortical tension = γp(p-P)2 (squared)
what properties do cells have, which cause a reversible effect?
stickiness
adhesion
area of conservation
so whatever pull or pressure you put on the cell will reverse the effect
in silico cells
non-polar
membrane has small fluctuations that are non-directed
cells tend to round up alone but have honeycomb formation when they adhere to form aggregates
what are adhesions mediated by?
between cells through cadherins that cells express on their membranes
what do adhesion differences lead to?
different cell types will then lead to tissues separating or auto-organising
body plan of a plant
plants do not change neighbours
no cell sorting or differential adhesion
they don’t have a set number of organs so can differ
complex plant morphology can depend on
gene regulatory networks
plant-soil interactions
environmental conditions
ecological interactions
how does the structure of auxin relate to its functions?
cyclo - cell elongation
nitrogen - cell differentiation
carboxylic acid - cell division
auxin
auxin moves through specialised membrane transporters
auxin gradients are instructive for development
in conditions of less auxin, they sort expanding/dividing
the coordinated direction of their coordinated transporters was key to organise the root due to auxin being dynamic for stable growth
the pattern gives instructions, even in a growing tissue
tissue development in plants vs animal
the plant root and animal gut
these mechanisms are very similar (animals in intestine crypts)
different scales but they are similar through gradients, the cell dynamics have to be coordinated spatially
the idea that plants are continually growing structures
keratocyte
no nucleus - demonstrates that even in the first few hours when there is no nucleus, the cell can still move
animal cells
cell deformation and motility by actin cytoskeleton using G-actin, F-actin and side branching by Arp2/3
note that monomers are added at the leading edge of actin
small G-proteins
molecular switches
the ‘on’ needs to be GDP bound to be internalised by the cytosol
they give rise to polarity so having regions with low amounts of Rac and regions of high amounts of Rac in a homogeneous cell
essential element: fast cytosolic diffusion, slow membrane diffusion
for polarity
Rac and Cdc42 in the front and Rho in the back
what is there cross talk between for systems biology?
G-proteins through the GEFs
what steers the cytoskeleton?
