Ch. 4 pt 2 Flashcards
_______: a proximate interaction where one cell changes the behavior of another cell
induction
_______ cell produces signal, and _______ cell/tissue induced by signal
inducer
responder
_______: the ability to respond to an inducing signal
competence
In order for a cell/tissue to be competent, it must have a _______ allowing it to receive the signal
receptor
_______ optic vesicle induction experiments were used to show induction and competence interactions
Xenopus
(slide 19)
In amphibians, the first inducer of the lens may be the _______ and heart-forming _______ that underlie the lens-forming ectoderm during early and mid gastrula stages
foregut endoderm
mesoderm
in amphibians lens formation, the Second inducer appears to be the ______ promoting the production of Pax6 TF in the neural ectoderm
neural plate
In amphibians, the neural plate promotes the production of _______ in the neural ectoderm
Pax6
_______ provides competence for lens ectoderm to respond to inducers from the optic cup cells (amphibians)
Pax6
What are the steps to mouse lense formation? (6)
1) optic vesicle induces ectoderm to form lens placode
2) lens placode induces optic vesicle to form optic cup
3) Optic cup induces lens placode to invaginate
4) invagination induces optic cup to form 2 layer retina
5) Futher invagination forms lens vesicle and lens capsule
6) lens placode induces ectoderm to form cornea
What is the optic vesicle?
neural ectoderm
thickening on surface ectoderm in mouse lense formation is called
lens placode
What are the 2 modes of induction?
1) instructive interactions
2) permissive interactions
_______: a signal from the inducing cell is NECESSARY for initiating new gene expression in the responding cell
instructive interactions
_______: in this type the responding cell already has been specified, it just needs the correct environment and signals to allow the expression of those traits
permissive interactions
_____ organs are composed of an epithelium and an associated group of mesenchyme
ALL
what are the two types of specification commonly dealt with in epithelial-mesenchymal interactions?
1) region specification
2) Genetic specificity of induction
_______: interactions between epithelium and mesenchyme can create regionally specified structures
region specification
_______: mesenchyme may instruct epithelium as to which genes to activate, but epithelium can only comply so far as the genome permits
genetic specification of induction
Sperman and Schotte transplanted flank ectoderm from a _______ grastrula onto the region of a _______ gastrula destined to become the mouth, and vise-versa
frog
newt
The _______ larvae developed mouthparts in the correct location, however, the specific structures made were those from the _______ ectoderm embryo
chimeric
original
- the ectoderm responded to the mesoderm by making the only mouth it “knew” how to make
In drosophilia respitory system, reorganization of the cells in each sac produce primary, secondary, and tertiary branches without _______ or _______
cell division or apoptosis
Tracheal development in drosophilia is initiated when nearby cells secrete _______, which is a _______, bound to cell membrane receptors on epithelial cells
Branchless protein (BNL)
chemoattractant
The cells receiving the most signal are attracted and migrate towards the signal via changes in _______ and _______
cytoskeleton
cadherin expression
Leaders cells express the _______ protein
Breathless protein (BTL)
_______ cells guide the rest of the surrounding cells to become the tracheal tube
leader
_______: a diffusible molecule that affects distance cell fates by concentration
Morphogen
What does Morphogen mean in greek?
Form-Giver
Morphogen are _______ produced in the cell or secreted _______
transcription factors
paracrine factors
_______: cell(s) producing the morphogen
- transmitting cell
source
_______: receiving cells affected by the morphogen
sink
Morphogen act in _______: action on the receiving cell is dependent on concentration
analog
What is the morphogen explained in xenopus development?
activin
activin, a paracrine factor in the ______ family was embedded into beads and placed on unspecified cells in the xenopus experiment
TGF-β
Explain what activin does to unspecified cells in:
1) high concentrations
2) medium concentrations
3) low concentrations
1) induced expression of googsecoid (dorsal structures)
2) induced Xbra (muscles)
3) normal development into blood vessels and heart
For a ligand to induce a cellular response, it must bind to a receptor, which starts a _______ of events within the cell that ultimately regulate a response
cascade
What are the 2 usual end points of signal transduction cascades?
1) regulation of transcription factors
2) remodeling of the cytoskeleton
What is the most common receptor that has enzymatic function and can be activated?
Receptor Tyrosine Kinase (RTK)
