Development Flashcards
important concepts of embryonic development (4)
universal mechanisms of animal development
proteins can be substituted across species
inductive signaling
regional determination
regional determination
once a tissue reaches a certain point in its developmental process, its destined to be that tissue
signal proteins that are used over and over again as inducers in animal development (5)
receptor tyrosine kinase (RTK) TGFB superfamily Wnt Hedgehog Notch
proteins can be substituted across
species
multicellular organisms are enriched in
proteins mediating cell interactions and gene regulation
regulatory DNA defines the
development program
inductive signaling (4)
cell-cell signaling
cell signaling cascades
acts over great distances
starting point (cell or cell cluster)
in inductive signaling, cells that are close get
a higher concentration of signal than those further away
in inductive signaling, cells directed to new
developmental pathway
sequential induction
initial induction induces changes to cells which induce changes to more cells, etc
pre-somitic mesoderm from a thoracic vertebrae-forming region in transplanted from a state 10 chick embryo into the cervical region of a state 8 embryo
skeleton of recipient embryo at 9 days shows cervical vertebrae developing as thoracic vertebrae
what are the four essential processes by which an embryo is constructed?
cell proliferation
cell specialization
cell interaction
cell movement
— — vary greatly across the animal kingdom
gestational periods
patterning
cells produced by cleavage get organized into layers and groups of cell masses through gastrulation
patterning needs to occur in - dimensions
3
what are the 3 dimensions of patterning
anterior-posterior (top to bottom)
dorsal-ventral (left-right)
proximal-distal (front-back)
differentiation
cells begin to form specific and specialized structures
growth
cell divisions that form more cells with identical functions as the parental cell
paradigm of development
in every species and at every level of organization, complex structures are made by repeating a few basic themes with variations
similarities in embryos if different species provides evidence of
common ancestor (patterns of embryo development are also important)
primitive streak
forms as an influx of cells into the interior to form the 3 cell layers (mesoderm, endoderm, ectoderm)
neural crest cells
embryonic cell population that is localized between the developing neural tube and the non-neural ectoderm. (there are also adult neural crest cells like cells that have been identified in many tissues)
some neural crest cell exhibit “—” in that they can give rise to multiple differentiated cell types
stemness
in the formation of the crainofacial structures (and many other structures) the neural crest cells migrate through
restricted pathways to form the developing structures
cell migration is a tightly regulated process and the NCCs receive cues such as
morphogens and growth factors that restrict their movement and determine fate
segmental plate mesoderm gives rise to
epithelial somites
epithelial somites give rise to (2)
dermamyotome
sclerotome
dermamyotome gives rise to (2)
dermatome
myotome
hierarchical gene control
coordinate genes gap genes air rule genes segment polarity genes homeotic selector genes other genes
homeosis
replacement of one body part with another
ed lewis reasoned that these were genes responsible for
establishing the fate of individual segments
gene products are
gene regulatory proteins
all contain a highly conserved
DNA binding homeodomain sequence of 60 amino acids
the corresponding segment in the 180 bp DNA sequence is called a
homeobox
how genes are interspersed among large stretches of
regulatory DNAregions
how genes are expressed — according to their order in the hot complex
sequentially
how complex carries a permanent record of
positional information
there are hundreds of other homeobox genes in the genome, bu they are
scattered and not cluster in complexes
pattern of gene expression of each gene follows
head to tail and order on chromosomes
a homeobox code drives
tooth formation
when does cleft lip and palate occur?
early in fetal development. in humans, the lip forms between the 4th and 7th week of pregnancy and the palate forms between weeks 6 and 9
formation of the craniofacial structures in early development requires the proper migration of
neural crest cells and their differentiation
there are universal mechanisms of development that are essentially used by
all animals, including invertebrates
the complexity of animals is a function of the
gene expression control systems that drives development
multicellular organisms are enriched in proteins that (2)
mediate cell-cell interactions and control gene expression
cells in the adult organism retain a record of
signals they received in early embryonic development, which is necessary. for them to maintain their specialized characteristics
