The entry of Na+ causes the opening of more voltage- gated Na+ channels and further depolarization, setting up a positive feedback loop .

TLS Online TPP Program

#Id: 4750

#Unit 5. Developmental Biology

During first cleavage, the metaphase plate is closer to the posterior, & fertilized egg is divided into two cells:

one having the anterior PARs (PAR-6 and PAR-3)

one having the posterior PARs (PAR-2 and PAR-1)

TLS Online TPP Program

#Id: 4751

#Unit 5. Developmental Biology

C. elegans demonstrates both the conditional and autonomous modes of cell specification. 

TLS Online TPP Program

#Id: 4752

#Unit 5. Developmental Biology

The P1 cell develops autonomously without the presence of AB, generating all the cells it would normally make, and the result is the posterior half of an embryo.

TLS Online TPP Program

#Id: 4753

#Unit 5. Developmental Biology

AB cell in isolation makes only a small fraction of the cell types it would normally make.

TLS Online TPP Program

#Id: 4754

#Unit 5. Developmental Biology

The determination of the P1-derived somatic founder cells (MS, E, C, and D)are autonomous, with cell fates determined by internal cytoplasmic factors SKN-1, PAL-1, and PIE-1

TLS Online TPP Program

#Id: 4755

#Unit 5. Developmental Biology

The SKN-1 protein is a transcription factor that initiates the activation of those genes responsible for forming the pharynx and intestine.