Snail and Twist promote expression of genes involved in cell migration, loss of cell-cell adhesion, loss of cell polarity, and increase the production of proteases that digest the basement membrane

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#Id: 1588

#Unit 5. Developmental Biology

Primitive Streak

First arises from a local thickening of the epiblast at the posterior edge of the area pellucida (Koller’s sickle)

By stage 2, the primitive streak cells form a third layer that lies between the hypoblast and epiblast cells.

 By stage 3, the primitive streak has become a definitive region of the epiblast, with cells migrating through it to become the mesoderm and endoderm.

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#Id: 542

#Unit 2. Cellular Organization

Hook and filament are composed of monomeric subunits (flagellin) arranged in a helical fashion. 

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#Id: 3720

#Unit 10. Ecological Principles

Clement’s organismic model - Competition causes sharp boundaries between groups of species; certain species group together.

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#Id: 5414

#Unit 7. System Physiology – Animal

Astrocytes, which are found throughout the brain, are of two subtypes:

Fibrous astrocytes

Protoplasmic astrocytes

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#Id: 1367

#Unit 4. Cell Communication and Cell Signaling

All STAT proteins contain: 

An N-terminal DNA-binding domain

An SH2 domain