what is primary and secondary constriction ?????

Dear student,
Refer below for above asked query:-
The primary constriction of the chromosome is centromere.
The secondary constriction of chromosome is present in addition to primary constriction in few chromosomes.
They are helpful to identify the chromosome from which they have been formed.
Secondary constriction is also called as Nucleolar Organiser Region(NOR) involved in the formation of nucleolus.



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