devlopmnt Flashcards
What are Calcium independent cell adhesion molecules?
These are members of Ig superfamility of proteins.
Ex-neural cell adhesion molecules (N-CAM) & platelet endothelial cell adhesion molecules (PE-CAM)
Mesoderm affinity is not merely due to position in embryo b/c the close associations can be restored even if they’rej disrupted
jj
Ig domains are __ domains. What type of bonds form
protein-protein; H-bond
What are calcium dependent adhesion molecules called? Examples include __
cadherins; neural cadherin (N-cadherin) & epithelial cadherin (E-cadherin)
Calcium forms a bridge between 2 cadherins on different cells
Caderin proteins interact with other via a ___ bridge
Ca2+
What are sugar mediated adhesion molecules? Examples include ___
Proteins on 1 cell bind to polysaccharides (sugar polymers) on another cell
selectins - found in synctiatrophoblast that is bound to wall of uterus which had GPs
It is required for implantation of embryo into uterine wall (tennis ball on Velcro)
Cell adhesion molecules may also be linked to signaling pathways. For example, N-CAM cytoplasmic domain can be ___ & can interact iwth intracellular signaling molecules. Therefore, a cell may express ___ when bound to its identical neighbors
phosphorylated; express different genes
At about 8-cell stage of development ___ is first expressed in the embryo. The cells change from being loosely attached to a very __ ball. This may be the reason that twinning can no longer occur after about __ cell stage. The cells are too firmly ___
E-cadherin; compact; 8; attached
During early gastrulation, all cells of ecodermal layer express ___. When neural induction occurs, future neural cells down regulate __ & express ___
E-cadherin; E-cadherin; N-cadherin
What is on the edge of the neural induction?
neural crest
Initially all cells of neural plate express __. However, as neural tube starts to close, the crest at neural crest lose __ expression. These cells are now free to ___. Neural crest cells that finally contribute to ganglia __ N-cadherin so that they can interact with other neural cells
N-cadherin; N-cadherin expression; migrate; re-express
Cells of inner cell mass express ____. First, multiple independent cells in blastocysts express ___. These cells move inside to form the ICM. Remember that alteration in cell adhesion can led to changes in gene expression.
PE-CAM; PE-CAM
During early development, cell movement & cell shape play critical role in formation of many different strcutures
.
What is intercalation?
“insert b/w 2 others”
This movement functions to elongate embryonic tissues & involves both cell movement & changes in cell adhesion. One of the best examples is lengehning of notochord along cranio-cadual axis.
Intercalation makes it ___(longer/shorter)
longer
The notochord can be seen to become __ & ___ as the cells intercalate
narrower & longer
At a number of times during early development, cells lose their __ properties, leave a specific cell layer & becomes ___ - they become ___. EMT (epithelial-mesenchymal transition) is required for __, ___ & ___
adhesive; migratory; mesenchymal
gastrulation, neural crest migration & heart valve formation
Two TF factors __ & ___ are expressed in mesenchymal cells & regulate migratory phenotype
snail & slug
Expression of snail & slug in tumors is associate with increased ___ & __
EMT & metastasis
Epithelial cells express intermediate filament proteins of keratin family. Keratin filaments connect to other epithelial cells through ___ contacts
cell-cell
__ is a marker of mesenchymal cells - it is also a marker of __ & ___
Vimentin; invasive & metastatic tumor cells
Metastatic tumor cells lose their epithelial organization & express vimentin
Cells in an epithelium can constrict either their basal or apical surfaces & change shape. In many cases, a cuboidal cell takes on ___. Coordinate shape change in cells of epithelium brings about change in shape of tissue - ex - neural tube folding
wedge shape
During development some cells undergo programmed cell death. This is an integral part of certain developmental programs. It isn’t to be confused with ___ which is normal cell death due to infection/injury.
necrosis
Apoptosis involves complex series of ___ & ___. In fact, chromosomes are completely fragmented so that ell has no chance of recovery.
protein degradation & DNA degradation events
A remarkable examples of apoptosis occurs during development of ___. Cells in limb bud selectively apoptose to create separations b/w digits
digits
What is syndactyly
webbed fingers or toes
1/2000 births
Apoptosis is also found in ___ formation
heart valves
Formation of mouth & anus is via ___. __ is responsible for removal of cells to make a clear opening
apoptosis; apoptosis
ApoptoWhat is Treacher-Collins syndrome?
gene responsible has recently been identified. Loss of 1 copy of gene causes neural crest cells to apoptose - not enough cells to form facial structures completely
After embryonic development, most crtiical role of apoptosis is ___. It’s likely that many spontaneous tumors arise in our bodies during our normal lifetimes but vast majority of these are destroyed by apoptosis. Only those cells that escape apoptosis can go onto cause cancer. Mutation in genes of apoptosis pathway commonly occur in __. Apoptosis genes function as___.
protection against tumors.
tumor; tumor suppressor genes
