NEET BIOLOGY

Detailed explanation-1: -During prometaphase the microtubules of the mitotic spindle attach to the kinetochores of condensed chromosomes. The kinetochores of sister chromatids are oriented on opposite sides of the chromosome, so they attach to microtubules emanating from opposite poles of the spindle.

Detailed explanation-2: -During ‘prometaphase’, chromosomes oscillate back and forth between centrosomes and the center of the cell while microtubules attach to the kinetochore areas of chromosomes facing the opposite mitotic poles, therefore ensuring equal separation and subsequent distribution to the dividing daughter cells.

Detailed explanation-3: -During prometaphase, the physical barrier that encloses the nucleus, called the nuclear envelope, breaks down. The breakdown of the nuclear envelope frees the sister chromatids from the nucleus, which is necessary for separating the nuclear material into two cells.

Detailed explanation-4: -Spindle microtubules can be divided into three major classes: kinetochore microtubules, which form k-fibers ending at the kinetochore; interpolar microtubules, which extend from the opposite sides of the spindle and interact in the middle; and astral microtubules, which extend towards the cell cortex.

Detailed explanation-5: -Other microtubules bind to the chromosome arms or extend to the opposite end of the cell. During the cell division phase called metaphase, the microtubules pull the chromosomes back and forth until they align in a plane along the equator of the cell, which is called the equatorial plane.