Morphogens Flashcards
What are the types of signalling between cells
diffusible signals, membrane bound signals
Describe diffusible signals between cells
between membrane bound receptors or intracellular receptors
Give an example of membrane bound receptors used for signalling
growth factors
Give an example of intracellular receptors used for signaling
steroid hormones
Describe morphogens
Signalling molecules that can generate shape, and a concentration grad
How are morphogens produced
from a localised source
How are morphogens usually sensed?
through cell surface receptors
What does the french flag model show?
that cells respond differently to different levels of pigment
What type of development does the french flag model account for?
regulative development
How are morphogens transported?
simple diffusion, transcytosis, and by the extracellular matrix
Describe transcytosis
signalling molecules are taken up by vesicles
Give examples of signalling centres
zone of polarising activity in CLB, bicoid gradient,
Where is bicoid usually located?
localised to anterior end
What does bicoid code for
transcription factor
What does bicoid regulate
expression of hunchback
What produces bicoid
maternal mRNA from nurse cells
What is the function of bicoid
aid segmentation patterning
induction - definition
signalling from one cell type to another - change in specification of responding cell
What does grafting of the blastopore lip induce
formation of secondary embryo and axis
What happens if the blastopore lip is grafted at a later stage
bud of extra tissue forms - X complete duplication
Describe competence
ability to respond to a signal
Describe the animal cap assay
mesodermal zone is removed, animal & vegetal tissue fuses, mesodermal tissue is induced
What is the inducing tissue in the animal cap assay
vegetal tissue
What is the animal cap fated to become
neural tissue
What is the animal cap specified to become
epidermis
What can the animal cap be induced to become
muscle
What are the uses of the animal cap assay
identify source of mesoderm inducing signals, identify mesoderm inducing factors
What are the mesoderm inducing factors in the animal cap assay
activin
What is the source of mesoderm inducing signals in the embryo - animal cap assay
different signals sent between dorsal & ventral on animal side
