In an individual heterozygous for a deletion, the normal chromosome loops out during chromosome pairing in prophase I.

 

TLS Online TPP Program

#Id: 4738

#Unit 5. Developmental Biology

The anterior-posterior axis is determined before the first cell division, and the cleavage furrow is located asymmetrically along this axis of the egg, closer to what will be the posterior pole.

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#Id: 4739

#Unit 5. Developmental Biology

The stem cell lineage always undergoes meridional ,division to produce

(1) An anterior founder cell (AB)

(2) A posterior cell (P1) that will continue the stem cell lineage.

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#Id: 4740

#Unit 5. Developmental Biology

The founder cell (AB) divides equatorially, while the P1 cell divides meridionally (transversely) to produce another founder cell (EMS) and a posterior stem cell (P2).

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#Id: 4741

#Unit 5. Developmental Biology

The decision of the anterior and posterior axis depends on the position of the sperm pronucleus in egg.

TLS Online TPP Program

#Id: 4742

#Unit 5. Developmental Biology

C. elegans oocyte use the “partitioning-defective,” or PAR proteins, in establishing cell polarity. 

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#Id: 4743

#Unit 5. Developmental Biology

Cortical cytoplasm contains PAR-3, PAR-6 & PKC-3 Internal cytoplasm contains PAR-2 and PAR-1