Question

Congression occurs during
A. Early prophase
B. Late prophase
C. Early metaphase
D. Late metaphase

Answer 1

It is an enactment of coming together, i.e. the migration of chromosomes during cell division (significant step of mitosis) to the spindle equator to develop a metaphase plate is called as chromosome congression.

Complete step by step answer: Congression occurs during the early metaphase stage. The interaction among opposing pulling or pushing forces to reach an optimum close the spindle equator is established on chromosome congression. In human cells, however, chromosome bi-orientation and force balance at prometaphase kinetochores really isn’t needed for chromosome congression, while chromosome congression frameworks were not necessarily involved in ensuring post-congressional chromosome orientation. Therefore, qualitative characteristics evaluate chromosome congression and conservation of alignment. In reality, now it is obvious not all chromosomes are using the same congressional mechanism to the spindle equator. Chromosome congression perfectly reflects the very first mitosis challenge and ends with the development of a metaphase plate, a metazoan mitosis signature, and exists in near spatial-temporal coordination with both the mitotic spindle assembly which modulates the relationships of microtubule-chromosome necessary for chromosome movement.
Hence, the correct answer is option C.

Additional information: A so-called "direct congression" mechanism wherein chromosomes coordinate after bi-orientation and the formation of end-on kinetochore-microtubule attachments is being used by those chromosomes which are already favourably located among both poles whenever the nuclear envelope breaks down. This facilitates the controlled action of kinetochore pulling forces and powers of polar ejection around chromosome arms which during or after the congression control chromosome oscillatory motions. The nuclear envelope is becoming more and more indistinct in early prophase and chromatin fibres have become more packaged and compact. And although nuclear membrane and the nucleolus gradually vanish completely in the late prophase. "The chromosomes are very distinctive, simple to recognize and comprise of the 2 parts of the sister chromatids with transparent" arms.

Note: The hypothesis for just an integrated chromosome congression template in eukaryotic cells fundamentally focuses on the following constraints: the position of the chromosome proportional to the spindle poles after the breakup of the nuclear envelope, the formation and bi-orientation of stable end-to-end kinetochore-microtubule connectors, cohesion between kinetochore- and arm-associated motors as well as spatial signatures.