Flashcards in Devo Lect 8 + 9 - Cell connections Deck (16)
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2
Townes and Holtfreter experiment
separated cells with alkaline solution which spread out, placed in nutrients. Then they clumped together, moved about, then stop (stuck together)
3
Cell adhesion molecules
Used in epithelial sheets, serve to condense mesenchyme; eg L-selectin on blastocyst; cadherins
4
Cadherins
very common; homophilic (bind to same type); need Ca to bind; link to cytoskeleton (actin); usually cause contact inhibition. E (embryonic/ectodermal), P (placental), N (neural) types
5
Cadherin knockout mice
E knockouts: cannot implant; N knockout: nervous system doesn’t develop much, aborted
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CAMs
Cell Adhesin Molecule; immunoglobulin-like domains, homophilic; N-CAM important in brain development; can work with cadherins; attraction or repulsion (low or high sialic acid - negative charge)
7
Substrate adhesion molecules
bind cells to ECM (basal lamina); fibronectin: glycoprotein binds to integrins, allows cells to bind to it and move along
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Integrins
Bind fibronectin at RGD a.a. sequence, provide anchor; can also cause signal transduction as things bind to it
9
Cell junctional molecules
Gap junctions; form at morula stage and in early heart;
10
Cell adhesion in implantation
Blastocyst has L-selectin, E and P-cadherins so it can bind to endometrium wall; integrins on uterus and fibronectins on outside of blastocyst; serve to bind and signaling
11
Cell crawling
Protrusion of leading edge; form focal contacts; retraction of trailing edge
12
Cell motility components
contractile elements of cytoskeleton needed; lamellipodium: big front edge, more continuous; filopodia: small, spiky projections; focal contacts bind to substrates (ie. integrins); microfilaments (major) and microtubules
13
Microfilaments in cell motility
Major contributor; Constantly forming and breaking down; high concentration along the front edge; actin experiments (blocking it)
14
Haptotaxis
Guiding molecule is not freely diffusable, attached to something; ex: mesoderm cells follow fibronectin as they migrate inward
15
Galvanotaxis
Changes in voltage which can alter cellular movement, align themselves. Important in wound healing. Skin and nerve cells respond to this
16
Contact guidance
One cell moves and creates a path, another cell will follow
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