scrunching model -proposes that DNA downstream from the stationary, promoter-bound, polymerase is unwound and pulled into the enzyme. The DNA thus accumulated within the enzyme is accommodated as single-stranded bulges.

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#Id: 1028

#Unit 5. Developmental Biology

Sox family of transcription factors

Inhibit the formation of epidermis and neural crest by blocking the transcription and signaling of BMPs

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#Id: 1029

#Unit 5. Developmental Biology

There are two principal modes of neurulation: 

1. Primary neurulation

2. Secondary neurulation

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#Id: 1030

#Unit 5. Developmental Biology

In primary neurulation, 

cells surrounding the neural plate direct the neural plate cells to proliferate, invaginate into the body, and separate from the surface ectoderm to form an underlying hollow tube.

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#Id: 1031

#Unit 5. Developmental Biology

In secondary neurulation, 

the neural tube arises from the aggregation of mesenchyme cells into a solid cord that subsequently forms cavities that coalesce to create a hollow tube.

 

TLS Online TPP Program

#Id: 1032

#Unit 5. Developmental Biology

Primary neurulation forms the anterior portion of the neural tube

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#Id: 1033

#Unit 5. Developmental Biology

Secondary neurulation forms the posterior portion of the neural tube