Orthogenesis - “Straight-line evolution,” held that the variation that arises is directed toward fixed goals.

So that a species evolves in a predetermined direction by some kind of internal drive, without the aid of natural selection.

TLS Online TPP Program

#Id: 1468

#Unit 4. Cell Communication and Cell Signaling

A cadherin-family member CDHR3, highly expressed in epithelial cells in the human airway, as a receptor for RV-C (virulent class C rhinoviruses).

TLS Online TPP Program

#Id: 1469

#Unit 4. Cell Communication and Cell Signaling

In cultured cells, C → Y mutation in the EC5 domain of CDHR3 increases the cell-surface expression of CDHR3 and the binding and replication of RV-C.

TLS Online TPP Program

#Id: 1470

#Unit 4. Cell Communication and Cell Signaling

A protein called Snail that suppresses the expression of E-cadherin is associated with the epithelial-to-mesenchymal transition.

TLS Online TPP Program

#Id: 1471

#Unit 4. Cell Communication and Cell Signaling

The extracellular matrix is a dynamic, complex meshwork of proteins and polysaccharides that contributes to the structure and function of a tissue. 

TLS Online TPP Program

#Id: 1472

#Unit 4. Cell Communication and Cell Signaling

The major classes of ECM molecules are: 

• Proteoglycans

• Collagens

• Multi-adhesive matrix proteins

 

TLS Online TPP Program

#Id: 1473

#Unit 4. Cell Communication and Cell Signaling

Integrins function as adhesion receptors and CAMs in wide variety of epithelial and nonepithelial cells, mediating cell-matrix and cell-cell interactions.