A nucleus injected into a Xenopus egg can replicate only once unless the nuclear membrane is permeabilized to allow subsequent replication cycles

TLS Online TPP Program

#Id: 98

#Unit 5. Developmental Biology

In conditional specification the array of interactions it has with its neighbors, which may include: 

cell-to-cell contacts (juxtacrine factors)

secreted signals (paracrine factors)

physical properties of its local environment (mechanical stress)

TLS Online TPP Program

#Id: 8162

#Unit 2. Cellular Organization

For selective export of certain membrane proteins from the ER contain a di-acidic sorting signal (Asp-X-Glu, or DXE), which binds to the Sec24 subunit of the COPII

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#Id: 7491

#Unit 4. Cell Communication and Cell Signaling

Non - templated N nucleotide addition in heavy chains results from TdT activity. 

TLS Online TPP Program

#Id: 2667

#Unit 7. System Physiology – Animal

At physiologic pH, the loop diuretics are anions that attach to the 

Cl−-binding site of the Na+-K+-2Cl− cotransporter.

 

TLS Online TPP Program

#Id: 6418

#Unit 2. Cellular Organization

The promoter of the araBAD operon from E. coli is activated in the presence of arabinose and the absence of glucose and directs expression of genes encoding enzymes required for arabinose metabolism. 

Unlike the cases of lac and gal genes, where a repressor and an activator work together, here two activators work together: AraC and CAP.