Question

The separation of two chromatids of each chromosome at early anaphase is initiated by
A. The interaction of centromere with the chromosomal fibres.
B. The elongation of metaphasic spindle
C. The force of repulsion between the dividend kinetochores
D. All of the above.

Answer 1

A kinetochore is a disc-shaped protein structure. This complex structure is linked among the chromosomes and microtubules of the spindle, it is thus important for proper chromosome segregation.

Complete answer:
To answer this question, first, we need to know the anaphase stage of cell division. Anaphase is a phase that occurs during eukaryotic cell division where the chromosomes are divided to the cell's opposite poles. The chromosomes are pulled back to the metaphase plate, in the middle of the cell before anaphase, metaphase stage occurs. Although the chromosomes were highly concentrated in the beginning of cell division, they continue to condense through anaphase.
Now, let us find the solution from the option.
Anaphase is the stage of mitosis after the metaphase when replicated chromosomes are split and the daughter chromatids are moved to the cell's opposite poles. The separation of two chromatids of each chromosome at early anaphase is initiated by the force of repulsion between the divided kinetochores. Kinetochores are a protein which forms a complex with a centromere of a chromosome during cell division.

Thus, the correct option is C. i.e. The force of repulsion between the dividend kinetochores.

Note: The spindle formation checkpoint occurs before anaphase can start. This cellular function confirms that all chromosomes are linked to microtubules and are arranged on the metaphase plate. After completion of this stage, the cell secretes an alert that produces anaphase promoting complex or APC, a substance which will act to start the process of dividing homologous chromosomes or sister chromatids, depending on which cell cycle is taking place.