Cell to Cell Communication in Development & Principles of Experimental Embryology Flashcards
organs are formed by interactions between
cells & tissues
define inducer
cells/tissues that produce a chemical signal which results in a change in another cell’s fate
what is the name for the process where a cell’s fate is changed?
induction
define responder
cells or tissues which receive the inducing signal
define competence
the ability of cells/ tissues to respond to inducing factors
competence is typically governed by _________. Give an example
chemical mediators
Ex: proteins
define reciprocity
a cyclical pattern of induction between a community of cells
give an example of an inductive interaction
the epithelial-mesenchymal interactions
list the 3 types of inductive interactions
- paracrine factors
- juxtacrine factors
- autocrine factors
describe paracrine factors
the diffusion of proteins over a short distance
describe juxtacrine factors
physical interactions between surface protein w/ cell receptor
describe autocrine factors
cells respond to their own paracrine factors
which factor travels greater distances: inducing or endocrine
endocrine
describe the notch pathway
the physical interaction between adjacent cells for the induction process
the notch pathway is an example of which type of signaling
juxtacrine signaling
explain the mechanism of the notch pathway
a portion of the responder is cleaved by protease enzymes to activate target genes
activation of what causes DNA to be exposed
histone acetyltransferases
what type of signaling is commonly found in the nervous sytem?
juxtacrine signaling
signal transduction is a a cascade of biochemical events that lead to
gene expression
in signal transduction what happens to the receptor
ligand binding causes a conformational change
signal transduction activates enzyme activity beginning w/ the
G-protein
what is key in signal transduction
phosphorylation
what are the 2 types of interactions between inducers and responders
- instructive interaction
- permissive interaction
describe instructive interactions
inducing tissue gives instruction for responding cells to commit to a specific pathway of development
give an example of an instructive interaction
mesenchyme and epithelial ectoderm leading to differentiation
describe permissive interaction
responder is already specified but needs the proper environment to develop
the RAS-G protein is a component of which signal transduction pathway
paracrine
the RAS-G protein is used by growth factors to
initiate cell growth and differentiation
mutation in RAS pathway leads to
human tumors
the JAK-STAT pathway is responsible for the…
differentiation of formed elements in blood and limb formation
mutations in the JAK-STAT pathway leads to
- dwarfism
- deficiency in specific blood types
why doesn’t the loss of a signaling protein result in abnormal development or death
b/c there is a great amount of repetition in the process of signal transduction
what provides additional sites to regulate signaling between pathways
cross talk between pathways such that they are intimately interconnected
what is cell to tissue formation dependent on?
basement membrane attachment sites
give examples of adhesion molecules
- collagen
- fibronectin
- proteoglycans
- laminin
proteoglycans aid in the delivery of
paracrine factors to receptor sites
integrins are proteins which
bind the ECM to the intracellular network
ECM binds to
actin filaments
ECM induces transcription factors to control __________ ___________ or even prevent ____________.
gene expression
apoptosis
connexin is a group of 6 identical proteins that form
a pore that joins cytoplasms
what is important in tightly connected cells like epithelia of the gut and neural tube
gap junctions
temperature alterations influenced what in amphibians
sex typing
seasonal variations affected the ________ ____________ in butterflies
phenotypic expression
UV irradation caused exposed amphibians to
decreased fertilization & survival rates
define mycosporin
melanin type protection produced by some species
define differentiation
development of specialized cell types
define commitment in cell specification
biochemical changes to determine a cells fate
what are the 2 stages of commitment?
- specification
- determination
describe the ‘specification’ stage of commitment
cell is capable of differentiating “autonomously” in vitro
is specification reversible?
YES
describe the ‘determination’ stage of commitment
capable of specification in vivo or when placed back into an embryo
is determination reverible?
NO
what are the 3 types of specification?
- autonomous
- syncytial
- conditional
describe autonomous specification
cells removed from blastomere develop normally
autonomous specification is aka a
mosaic development
autonomous specification is mostly seen in
invertebrates
syncytial specification is mostly seen in
insects
describe the syncytial specification
the nuclei divides within the egg and spreads throughout
the specification of cells by protein concentration is known as? what type of specification is this specific to?
morphogens
syncytial specification
conditional specification is mostly seen in
vertebrates
describe conditional specification
first forming cells in the blastomere have the ability to differentiate into various cell types
in conditional specification what directs the determination of a specific cell type
interaction of neighboring cells
define regulation
the ability of blastomeres to compensate the missing cell types
what is the germ plasm theory
heritable info. is carried by just gametes and not somatic cells
zygotes have inherited component for
various body regions
what were the 4 types of experimental approaches to germ plasm theory
- defect
- isolation
- recombination
- transplantation
what are stem cells
undifferentiated biological cells that can differentiate into specialized cells
stem cells are found in
multicellular organisms
what are the 3 different types of stem cells
- totipotent
- pluripotent
- multipotent
totipotent stem cells can differentiate into
embryonic and extraembryonic cell types
totipotent stem cells can construct a
viable organism
egg + sperm
pluripotent stem cells have the capacity to grow into
all cells of the embryonic body
when and where are the pluripotent stem cells isolated from
- when: during the blastocyst stage
- where: the inner cell mass
pluripotent stem cells are aka
embryonic stem cells
give an example of multipotent stem cells
hematopoietic stem cells
ONLY differentiate into different cell types
which type of stem cell is the most limited in its differentiation
multipotent
cadherins are
calcium adhesion molecules
catenins are
actin binding proteins that anchor cadherins
a deficiency in what can lead to embryonic abnormalities
calcium or cadherin