Mick Flashcards
How is gene expression modified?
Current environment and extracellular environment experienced by ancestors
How is gene expression modified?
Current environment and extracellular environment experienced by ancestors
How is gene expression modified?
Current environment and extracellular environment experienced by ancestors
Who directs spatial organisation of cells?
Morphogens
What are morphogenic fields?
Regions of the embryo that are distinguished by gene expression but are not committed to a specific cell fate yet
Define gastrulation
The process whereby the blastula becomes a gastrula with two or three layers of cells
What is Activin?
A classic morphogen inducing Xgsc expression at high concenration and Xbra at low conc
When is Xbra not expressed?
At low conc of activin in vitro
What is sequential induction?
It’s an alternative to the morphogen model where Activin is the source and Xbra is activated by less activin and also factors activated by Xgsc
What is a means of patterning tissues without morphogens?
Lateral inhibition
How does lateral inhibition work?
Slight random asymmetries in primordial cells form different types of cells through a positive feedback loop
How can be a similar effect be produced?
With a global inducer
Who inhibits the cell from becoming a mother sensory cell
Notch signaling from adjacent cells
Who is Delta?
The ligant of Notch
What cells become mother cells?
Those with high Delta
What can generate large scale patterns?
The reaction diffusion system
How is the polarization in Drosophila?
all axes are specified in the structure of the
unfertilized egg by maternal egg polarity genes.
How is dorsoventral polarization driven?
By a morphogen found on the ventral side that rehulates dorsal gene expression, downstream regulators like Sog and Dpp proteins
What is the homologous for BMP in insects?
Dpp
How is anterio-poterior polarity regulated?
Morphogen concentrations in combination in few hours of development
How is segmentation driven?
By lateral induction
Who regulates Hox genes?
The gap genes, pair-rule genes and
segment-polarity genes together
What is autoinhibitory gene expression in developmental timing?
Give rise to oscillations over time and thus create regulatory clocks with different frequencies depending on the number of nodes
What is the intron delay hypothesis?
intron length could
be a factor in the timing of gene expression.
