Question

Explain how sister chromatids are held together during cellular duplication.

Differentiate between anaphase A and anaphase B for chromosome segregation.

Answer 1

A chromatid is a condensed DNA subunit of a chromosome. The two chromatids of a duplicated chromosome are held together at a region of DNA called the centromere. Centromeres are the attachment points for microtubules, which are responsible for guiding the movement of chromosomes during mitosis and meiosis.

Anaphase A : involves the movement of chromosomes to either pole . A combination of different forces have been observed acting on chromatin but the primary force is exerted centrally at an attachment site known as kinetochore. Through the shortening of each kinetochore attached microtubule the primary force is produced at the midpoint of chromosomes.

Anaphase B: involves the separation of these poles away from each other. Force is generated by by a combination of spindle-poles pushing against one another and a pulling of spindle-poles away from each other by motors attached to the cell cortex.

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