Question

Which of the following events takes place during the anaphase stage of mitosis?
I.Spindle fibers attach to kinetochores of chromosomes.
II.Centromeres split and chromatids separate.
III.Chromatids move to opposite poles.
IV.Nucleolus, Golgi apparatus and E.R. Reform.
(a) I and II only
(b) II and III only
(c) III and IV only
(d) I and IV only

Answer 1

Hint: Anaphase in mitosis occurs after the Metaphase. In the metaphase, the chromosomes are lined up in the middle of the cell. The chromosomes are ready to be divided after this phase.

Complete step by step answer:
Anaphase is the fourth phase of mitosis of the cell. The event is marked by the separation of sister chromatids from each other to become an individual half of the chromosome with one pair of gene sets present in them. The sister chromatids which were lined up in the equatorial plane of the cell during the metaphase, are now pulled towards the opposite ends of the cells by the mitotic spindles present at the poles. The cell slowly gets longer due to the separation of the poles. The cells start to stretch apart due to the elongation of unattached microtubules of the mitotic spindle.

- Each of the separated chromatids has the full set of genes that gets combined later.
- These processes are carried down by a protein present in the cell known as ‘motor protein’.
- These motor proteins carry the chromosomes towards the opposite ends of the cell.
- The main important event in Anaphase is the functional division of sister chromatids.
- It ensures that the newly formed daughter cells will receive the separated chromatid copy in them.
So, the correct answers are ‘(b) II and III only’.

Note: Chromatids refer to one-half of the two independent chromosomes. Microtubules are continuous repeating structures of tubulin that form as a cell skeleton. It provides structure and shape to the cell during mitosis.