. Which one of the following precedes re-formation of the nuclear envelope during M phase of the cell cycle


(a)  Decondensation from chromosomes and reassembly of the nuclear lamina

(b)  Transcription from chromosomes and reassembly of the nuclear lamina

(c)  Formation of the contractile ring and formation of the phragmoplast.

(d)  Formation of the contractile ring and transcription from chromosomes

 

Best Answer

Answr: a

Solution: At telophase stage, nuclear membrane vesicles associate with the surface of individual chromosomes and fuse to reform the nuclear membranes, which partially enclose clusters of chromosomes before coalescing to reform the complete nuclear envelope. During this process the nuclear pores reassemble and the dephosphorylated reassociate to form the nuclear lamina. One of the lamina proteins (lamina-B) remains with the nuclear membrane fragments throughout mitosis and may help nucleate reassembly. After the nucleus reforms, the pores pump in nuclear proteins, the chromosome decondense and RNA synthesis resumes, causing the nucleolus to reappear.

 

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