Question

Centromere is required for
a) Transcription
b) Crossing over
c) Cytoplasmic cleavage
d) Movement of Chromosomes towards poles

Answer 1

Hint : Centromere is a part of the chromosome that provides the site for the assembly of the kinetochore (a highly complex multi-protein structure) and two sister chromatids as well.

Complete answer :
During the process of mitosis, the spindle fibres attach to the centromeres via kinetochore, and all the chromosomes get arranged in an equatorial plane. This is followed by the movement of the chromosomes towards their respective poles followed by cell division. So, the centromere is required for the movement of chromosomes towards poles.

Additional information With the onset of metaphase and at the end of prophase, the chromosomes align along the cell equator. Every chromosome has microtubules extending from its kinetochore connected to each pole. The tension within the cell becomes balanced, and the chromosomes remain still. Besides, the spindle is now complete, and three groups of spindle microtubules are involved.
- Kinetochore microtubules: the chromosome are attached to spindle pole by these microtubules,
- Interpolar microtubules: These extend to the opposite of spindle pole across the equator, and
- Astral microtubules: These extend from the spindle pole to the cell membrane.
Anaphase is followed by Metaphase, during which each chromosome's sister chromatids separate and move to opposite poles of the cell. It involves the enzymatic breakdown of cohesin (linker between sister chromatids) causes this separation to occur. The changes in microtubule length provide the mechanism for chromosome movement.

So, the correct answer is ‘Movement of chromosomes towards poles’.

Note: The centromere is present in every cell and has a specific DNA sequence. The movement of chromosomes is an important step during the cell cycle. Any alteration in this phenomenon might result in cells with no genetic material at all thus lethal.